Extracellular Microbial Polysaccharides - ACS Publications - American

22 Extracellular Microbial Polysaccharides—A Critical

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Overview JEREMY WELLS Biochem Design S.p.A., Via A. Bargoni, 78, 00153 Rome, Italy It is the interest of this paper to present a c r i t i c a l overview of commercially significant extracellular microbial polysaccharides within the context of the industrial hydrocolloid or gums market. Polysaccharide hydrocolloids obtained from plants and seaweed have been used successfully for food, petroleum, textile and numerous industrial applications for several years. Polysaccharides are produced extracellularly by many microorganisms now available. Several of these new hydrocolloids produced microbially, have shown themselves to be commercially significant. The reasons for the commercial exploitation of these microbial polysaccharides is because of their unique physical and constant chemical properties, regularity of supply, better functional properties and a lower biological use of oxygen. The commercial usefulness of polysaccharides is based on their ability to alter the rheological properties of water. Present major markets for these polysaccharides exist in the food and the petroleum drilling industries. Large future growth is expected to come from enhanced oil recovery. This paper considers the use of microbial polysaccharides in competition with other water soluble gums in the food industry. It also studies the use of polymers in enhanced oil recovery, when i t compares polysaccharides with polyacrylamides. To provide this overview of the industrial gums markets, it has been necessary to review data recently published or in publication. Particular thanks are given to Tate and Lyle Ltd. for allowing publication of data recently obtained durina a market feasibility study made on their behalf. Particular thanks are given to Dr. C.J.Lawson, without whose cooperation this paper would have been that much more difficult. THE MARKET FOR WATER SOLUBLE GUMS M o s t w a t e r s o l u b l e gums a r e t h e o r e t i c a l l y i n t e r c h a n g e a b l e . I n p r a c t i c e , most gums p o s s e s s u n i q u e c h a r a c t e r i s t i c s w h i c h guarantee t h e i r commercial use. 299

Sandford and Laskin; Extracellular Microbial Polysaccharides ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

300

EXTRACELLULAR MICROBIAL POLYSACCHARIDES

TABLE I CLASSIFICATION OF NATURAL AND SYNTHETIC WATER-SOLUBLE GUMS

Exemple


Origin

Tree Exudates

Seed E x t r a c t

Seaweed E x t r a c t s

Natural

Natural

Starches

Natural

Products

S t a r c h and Dérivâtes

Cellulose Derivatives

Synthetic

Petrochemical Derivatives

Gum A r a b i c K a r a y a Gum Gum T r a g a c a n t h and o t h e r s Guar Gum L o c u s t Bean Gum P s y l l i u m and others Agar Alginates Carrageenan and others Corn Starch Potato Starch T a p i o c a and o t h e r s Dextrans X a n t h a n Gums Pectin Gelatin Dextrins Starch Acetates Dialdehyde s t a r ches and o t h e r s Carboxymethylcellulose Methylcellulose Hydroxymethy1cell u l o s e and o t h e r Polyvinyl Alcohol Polyacrylic Acid Salts Ethylene Oxide Polymers and others


22.

WELLS

Extracellular

Microbial

Polysaccharides

301


T a b l e I l i s t s b o t h n a t u r a l and s y n t h e t i c gums i n common u s e a c c o r d i n g t o c l a s s . Gums h a v e d i v e r s e c h e m i c a l c o m p o s i t i o n , o r i g i n and f u n c t i o n a l i t y a n d a r e c l a s s i f i e d a c c o r d i n g t o t h e i r origin. The m a i n c l a s s e s o f n a t u r a l gums a r e t h e f o l l o w i n g : - Natural products - S t a r c h and s t a r c h dérivâtes - Seaweed e x t r a c t

- Tree exudates - Seed e x t r a c t - Cellulose derivatives

In the united States, i t i s reported that while the t o t a l e x p a n s i o n o f gums i s o n l y 1.3% p e r annum, t h e s y n t h e t i c p o l y m e r and m i c r o b i a l l y p r o d u c e d gums a r e i n c r e a s i n g b y o v e r 8% p e r annum. T h i s i n c r e a s e i n c o n s u m p t i o n o f m a n u f a c t u r e d gums i s a t t h e e x p e n s e o f p l a n t gums. T a b l e I I shows t h e c o n s u m p t i o n o f gums i n t h e U n i t e d S t a t e s d u r i n g 1973 a s r e p o r t e d b y R . L . W h i s t l e r . The o v e r a l l u s a g e o f gums h a s b e e n f a i r l y w i d e s p r e a d t h r o u g h o u t t h e i n d u s t r y . O r i g i n a l l y t h e t r e e e x u d a t e s were t h e most w i d e l y u s e d c l a s s o f gum. I n r e c e n t y e a r s t h e s e e x u d a t e s h a v e b e e n r e p l a c e d b y m a n u f a c t u r e d gums i n c l u d i n g x a n t h a n gum. Improved p r o p e r t i e s o v e r t h e s e p l a n t gums b y t h i s r a n g e o f m a n u f a c t u r e d gums, h a v e caused t h e s h i f t . P l a n t gums v a r y i n q u a l i t y and a r e d i s t r i b u t ed i n t h e raw s t a t e , s o r e q u i r e f u r t h e r p r o c e s s i n g i n c l u d i n g

Gum

TABLE I I THE CONSUMPTION OF INDUSTRIAL GUMS I N THE UNITED STATES (1973) (tons) Total Food Industrial Usage Usage Usage

Cornstarch Carboxymethylcellulose Methylcellulose Guar Arabic Pectin L o c u s t bean Alginate Ghatti Carrageenan Xanthan Karaya Tragacanth Agar Furcellaran

223,214 6,696 900 6,696 10,267 3,357 4,017 4,017 4,464 4,017 1,000 446 580 133 89

1,116,071 43,303 23,660 15,625 3,125 0 1,785 4,017 446 89 2,678 3,125 89 178 0

1,339,285 50,000 24,553 22,321 13,392 5,357 5,803 8,034 4,910 4,106 3,678 3,571 669 311 89

R . L . W h i s t l e r 1974



302


c r u s h i n g and c l e a n i n g b y t h e end u s e r . W h i l e t h e m a n u f a c t u r e d gums a r e i n t h e i r f i n a l s t a t e , r e a d y f o r d i r e c t u s e . The m a n u f a c t u r e d gums a r e o f t e n t a i l o r made f o r s p e c i f i c a p p l i c a t i o n o r premixed f o r d i r e c t a p p l i c a t i o n . These premixes b e a r a v a r i e t y o f names a n d a r e i n t e n d e d f o r s p e c i f i c p u r p o s e s . S e a s o n a l v a r i a t i o n s i n q u a l i t y , s u p p l y a n d p r i c e have o f t e n f o r c e d p r o c e s s o r s t o change t o m a n u f a c t u r e d gums. However when c o n d i t i o n s r e v e r t , these processors then p r e f e r t o continue t o use t h e r e l i a b l e m a n u f a c t u r e d gums. X a n t h a n f o r example h a s t a k e n much o f t h e gum t r a g a c a n t h m a r k e t i n t h e U.S. I t i s o n l y t h e f o o d , p h a r m a c e u t i c a l and c o s m e t i c i n d u s t r i e s t h a t s t i l l u s e t h e s e p l a n t gums. The p e r c e n t a g e d i s t r i b u t i o n o f t h e m a n u f a c t u r e d gums i n t h e U n i t e d S t a t e s has been r e p o r t e d as f o l l o w s : Percent D e t e r g e n t s and l a u n d r y p r o d u c t s Textiles Adhesives Paper Paint Food P h a r m a c e u t i c a l and c o s m e t i c Other

16 14 12 10 9 8 7 24

The m a i n demands f o r gums s t e p s f r o m t h e i r v a r i o u s f u n c t i o n a l p r o p e r t i e s and c a n be b r o k e n down i n t o t h e f o l l o w i n g : Functionality S t a b i l i z e r , s u s p e n d i n g a g e n t and dispersant Thickener F i l m f o r m i n g agent Water r e t e n t i o n agent Coagulant Colloid Lubricant o r f r i c t i o n reducer Other purposes

Percent

25 23 17 12 7 6 5 5

C o s t e f f e c t i v e n e s s a n d c o s t o f gums w i l l be t h e p u r c h a s e r s most i m p o r t a n t c r i t e r i a i n d e c i d i n g w h i c h gum t o u s e . T a b l e I I I g i v e s a range o f p r i c e s as r e p o r t e d by t h e Chemical Market Reporter. A l t h o u g h gum p r o d u c t i o n i s f a i r l y d i f f i c u l t t o a c c u r a t e l y d e t e r m i n e , T a b l e I V l i s t s some gum p r o d u c t i o n e s t i m a t e s o b t a i n ed f r o m v a r i o u s s o u r c e s . The v a r i o u s a p p l i c a t i o n s o f gums a r e d e t e r m i n e d by t h e i r cost e f f e c t i v e n e s s i nu t i l i z i n g p h y s i c a l properties t o perform specific applications.


22.

WELLS

Extracellular

Microbial

Polysaccharides

TABLE I I I Price, $ per l b


V a r i e t y o f Gum

1971

1975

8. 15 2.4C ^-2.80 1. 75 0.42 H).60 0.57 f 0 . 5 8 1 .64 v2.75 0.38 H).40 0 .35 τθ.40 0.80 H).90 0 .90 v0.95 0.52 f 0 . 5 8 0 .79 K>.98 0. 74 0 .89 2 .40 2. 22 0 .45 0. 60 2.50 v7.00 10 .20 U 4 . 0 0

A g a r USP Gum A r a b i c Gelatine, edible Guar gum, e d i b l e K a r a y a gum L o c u s t b e a n gum Methylcellulose Pectin CMC ( c a r b o x y m e t h y l c e l l u l o s e ) Gum T r a g a c a n t h

S o u r c e : I n t e r n a t i o n a l T r a d e C e n t e r , 1972 u p d a t e d f r o m C h e m i c a l Market Reporter.

TABLE I V WORLD PRODUCTION OF SELECTED GUMS Gum

Year

Agar 1 Alginate 1 Arabic 2 Carrageenan 1 Furcellaran 1 L o c u s t Bean 2 Methylcellulose 2 Pectin 2 Carboxymethylcellulose Xanthan

1973 1973 1966 1973 1973 1970 1972 1971 1969 1975

Sources:

2

INDUSTRIAL

Production

(tons)

7,950 17,000 60,000 8,000 1,200 15,000 25,000 9,000 60,000 5,000

1) J . N a y l o r FA0 P r o d u c t i o n , T r a d e and U t i l i z a t i o n o f Seaweed P r o d u c t s (1976). 2) R . L . W h i s t l e r

I n d u s t r i a l Gums ( 1 9 7 3 ) .


304



As p r e v i o u s l y m e n t i o n e d the f o l l o w i n g c l a s s e s :

t h e m a i n gums a r e c l a s s i f i e d

into

N a t u r a l P r o d u c t s . The f o u r most i m p o r t a n t h y d r o c o l l o i d s i n t h i s c l a s s a r e g e l a t i n , p e c t i n , d e x t r a n and x a n t h a n . I n t h e food i n d u s t r y over twenty thousand tons o f n a t u r a l p o l y s a c c h a r i d e s w e r e s o l d i n t h e U n i t e d S t a t e s i n 1975. T h i s was b r o k e n down i n t o 16,000 t o n s g e l a t i n e , 2,000 t o n s x a n t h a n and 3,000 tons p e c t i n . G e l a t i n i s p r e f e r r e d i n g e l a t i n d e s s e r t s , meat p r o d u c t s s u c h a s ham and l u n c h e o n meat and d a i r y p r o d u c t s . The p h o t o g r a p h i c and p h a r m a c e u t i c a l i n d u s t r i e s a r e t h e l a r g e s t u s e r s of h i g h grade g e l a t i n e . P e c t i n , because o f i t s g e l forming p r o p e r t i e s w i t h sucrose i s u s e d i n jams a n d c o n f e c t i n e r y . X a n t h a n h a s g a i n e d a c c e p t a n c e i n s a l a d d r e s s i n g s , c i t r u s d r i n k s , bakery items and d a i r y p r o d u c t s a s w e l l a s o i l d r i l l i n g muds and r e c o v e r y . Seaweed E x t r a c t s . Seaweed e x t r a c t s a r e o b t a i n e d f r o m two groups o f a l g a e , r e d algae which i s t h e source o f carrageenan and a g a r a n d b r o w n a l g a e w h i c h i s t h e s o u r c e o f a l g i n a t e s . The r e c e n t FA0 Seaweed R e s o u r c e s o f t h e W o r l d r e p o r t s l a r g e p o t e n t i a l f o r expansion i n t h i s group. P r e s e n t h a r v e s t s o f r e d and brown a l g a e a r e p u t a t 0.807 a n d 1.315 m i l l i o n t o n s r e s p e c t i v e l y w i t h p o t e n t i a l o u t p u t s l i s t e d a t 2.66 and 14.6 m i l l i o n t o n s of algae. E a c h o f t h e s e gums, h a s u n i q u e p r o p e r t i e s g i v i n g them e x c e l l e n t market p o t e n t i a l . Because o f i t s l o w g e l l i n g and heat r e s i s t a n c e , agar has a wide usage i n f o o d s . A l g i n a t e s a r e t h e most e x t e n s i v e l y u s e d gum o f t h e g r o u p and a r e u s e d i n d a i r y p r o d u c t s , c i t r u s b e v e r a g e s , b a k e r y f i l l i n g s , l i q u i d a n i m a l f e e d s , p h a r m a c e u t i c a l and many i n d u s t r i a l applications. Carrageenan has t h e l a r g e s t usage o f t h e group i n d a i r y , beverages and bakery p r o d u c t s . I t i s h e a v i l y used i n d a i r y products because o f i t s r e a c t i o n w i t h c a s e i n . Starch Derivatives. N a t u r a l starches are normally processed t o g i v e them p r o p e r t i e s f o r s p e c i a l a p p l i c a t i o n s . B e c a u s e of t h e i r s t r o n g adhesives p r o p e r t i e s , they are used i n adhesives and a r e h i g h l y c o m p e t i t i v e w i t h gum a r a b i c . Other uses i n c l u d e c e r a m i c s , f l o c c u l a t i o n , w e l l d r i l l i n g muds a n d p h a r m a c e u t i c a l s . Seed E x t r a c t s . The two m a j o r gums i n t h e g r o u p a r e g u a r and l o c u s t b e a n gum. G u a r i s o b t a i n e d i n I n d i a a n d P a k i s t a n , w h i l e l o c u s t s b e a n i s h a r v e s t e d i n S p a i n and t h e M e d i t e r r a n e a n a r e a . They a r e b o t h u s e d i n t h e d a i r y i n d u s t r y f o r c h e e s e m a k i n g and i c e c r e a n p r o d u c t i o n . G u a r gum i s t h e p r e f e r r e d i c e c r e a m s t a b i l i z e r . L o c u s t b e a n gum i s a v i s c o s i f i e r a n d b i n d e r o f f r e e w a t e r . Cellulose Derivatives. F o o d , drum, c o s m e t i c and d e n t i f r i c e p r o d u c t s a r e t h e f a s t g r o w i n g u s a g e o f CMC ( s o d i u m c a r b o x y m e t h y l c e l l u l o s e ) a n d MC ( m e t h y l c e l l u l o s e ) . MC c o s t s more t h a n CMC a n d h a s a US p r o d u c t i o n o f 30 m i l l i o n pounds a g a i n s t a US p r o d u c t i o n o f 74 m i l l i o n pounds o f CMC.



22.

WELLS

Extracellular

Microbial

Polysaccharides

305

Tree Exudates. The t r e e e x u d a t e s , gum a r a b i c , gum t r a g a c a n t h a n d gum K a r a y a h a v e a l l l o s t m a r k e t s h a r e s t o t h e s y n t h e t i c s a n d p r o c e s s e d gums. However, gum K a r a y a b e c a u s e o f i t s l a x a t i v e p r o p e r t i e s m a i n t a i n s a market. Gum t r a g a c a n t h h a s a w i d e r a n g e o f a p p l i c a t i o n s i n f o o d , t e x t i l e s , c o s m e t i c s and c e r a m i c s . However b e c a u s e o f s u p p l y d i f f i c u l t i e s and p r i c e d i f f e r e n t i a l i t h a s been r e p l a c e d t o a l a r g e e x t e n t b y x a n t h a n gum. Gum a r a b i c i s u s e d m o s t l y t o p r e v e n t c r y s t a l l i z a t i o n o f s u g a r s and a s a n e m u l s i f i e r t o k e e p f a t s u n i f o r m l y d i s t r i b u t e d . CMC, PVA and m o d i f i e d s t a r c h e s have t a k e n a l a r g e s h a r e o f t h e gum a r a b i c m a r k e t . MICROBIAL POLYSACCHARIDES OF COMMERCIAL SIGNIFICANCE A t t h i s t i m e o n l y t h r e e m i c r o b i a l p o l y s a c c h a r i d e s o f comm e r c i a l s i g n i f i c a n c e are i n commercial p r o d u c t i o n , dextran, p o l y t r a n a n d x a n t h a n . F i v e o t h e r s show p r o m i s e i n d e v e l o p m e n t and a r e a v a i t i n g d e c i s i o n s o n p o t e n t i a l c o m m e r c i a l e x p l o i t a t i o n . Dextran. Dextrans a r e p o l y g l u c a n s and have been produced i n t h e U n i t e d S t a t e s , C a n a d a , H o l l a n d a n d Sweden. They c a n be s y n t h e s i s e d f r o m s u c r o s e m i c r o b i a l l y f r o m many s t r a i n s o f c e l l f r e e c u l t u r e f i l t r a t e s o f l e u c o n o s t o c m e s e n t e r i d e s , though d e x t r a n s from o t h e r s t r a i n s w i l l d i f f e r both i n s t r u c t u r e and p r o p e r t i e s . M o l e c u l a r w e i g h t s may r a n g e w i d e l y . U s u a l p r a c t i c e i s t o o b t a i n a h i g h m o l e c u l a r weight m a t e r i a l and degrade i t by h y d r o l y s i s , s i n c e the d e x t r a n s t h a t are used i n the food i n d u s t r y must h a v e m o l e c u l a r w e i g h t s b e l o w 100,000, s i n c e o n l y t h e y a r e i n c l u d e d i n t h e GRAS l i s t o f t h e FDA. D e x t r a n s o l u t i o n s a r e c l o s e l y s i m i l a r t o l o c u s t b e a n gum. X a n t h a n . X a n t h a n gum i s p r o d u c e d f r o m g l u c o s e s o l u t i o n i n g r o w i n g c u l t u r e s o f xanthomonas c a m p e s t r i s . Commercial p r o d u c t i o n has been c a r r i e d o u t i n the U n i t e d S t a t e s s i n c e 1967 b y t h e K e l c o Company, who a r e c u r r e n t l y t h e m a i n m a n u f a c t u r e r a n d who p r o d u c e d a n e s t i m a t e d 5,000 t o n s o f x a n t h a n i n 1975. L o c a l e x p a n s i o n o f t h e San D i e g o p l a n t , t o g e t h e r w i t h a g r a s s r o o t s p l a n t i n Oklahoma f o r 10,000 t o n s a t an e s t i m a t e d c o s t o f 35 m i l l i o n d o l l a r s p l u s p l a n t b y Rhone P o u l e n c o f F r a n c e a n d G e n e r a l M i l l s c o u l d make a v a i l a b l e b e t w e e n 35-37J m i l l i o n pounds x a n t h a n b y 1978. T a t e a n d L y l e L t d . and H e r c u l e s I n c . h a v e announced a j o i n t - v e n t u r e t o enter i n t h i s market. C u r r e n t development s t a t u s o f m i c r o b i a l p o l y s a c c h a r i d e s i s l i s t e d i n A p p e n d i x A. The u n i q u e p h y s i c a l p r o p e r t i e s o f x a n t h a n h a v e f o u n d many i n d u s t r i a l a p p l i c a t i o n s i n such d i v e r s i f i e d i n d u s t r i e s as t e x t i l e p r i n t i n g , d r i l l i n g muds, s u r f a c t a n t f l o o d i n g , r u s t r e m o v e r s , and l i q u i d t y p e o f a n i m a l f e e d s . Most i m p o r t a n t p r e s e n t u s e i s t h e r e c o v e r y o f c r u d e o i l . The f l o w c h a r a c t e r i s t i c s o f x a n t h a n , c o u p l e d w i t h i t s s t a b i l i t y



306


t o pH, g i v e s i t a t e c h n i c a l a d v a n t a g e o v e r o t h e r p o l y m e r s i n d r i l l i n g muds. T h e r e i s a n e s t i m a t e d w o r l d u s a g e o f 1,800 t o n s in drilling applications. S c l e r o g l u c a n ( P o l y t r a n ) . T h i s p o l y s a c c h a r i d e has been dev e l o p e d by t h e P i l l s b u r y Company a n d m a r k e t e d u n d e r t h e t r a d e name o f P o l y t r a n . P i l l s b u r y c l a i m i m p o r t a n t f l o w c h a r a c t e r i s t i c s o v e r a w i d e r a n g e o f pH a n d t e m p e r a t u r e and s t a b i l i t y i n t h e presence of s a l t s . P o l y t r a n w i l l s t a b i l i z e bentonite c l a y s d u r i n g s t o r a g e , o v e r r a n g e s o f t e m p e r a t u r e a n d pH. I t i s u s e d i n t h e c e r a m i c , d r i l l i n g mud, and i n k s a n d c o a t i n g s i n d u s t r i e s . P r i c e s i n t h e r e g i o n o f 9-10,000 d o l l a r s p e r t o n p u t i t i n comp e t i t i o n w i t h x a n t h a n gum. OTHER MICROBIAL POLYSACCHARIDES BEING DEVELOPED Pullulan. T h i s p o l y s a c c h a r i d e has been developed by t h e H a y a s h a b a r a Company i n J a p a n . C o m m e r c i a l i n t e r e s t h a s b e e n shown o n a c c o u n t o f i t s a b i l i t y t o f o r m s t r o n g r e s i l i e n t f i l m s and f i b e r s a n d t h e e a s e i t c a n be m o l d e d i n t o s h a p e s . A t p r e s e n t p u l l u l a n i s o n l y i n t h e p i l o t plant stage. C o n s t r u c t i o n o f a p r o d u c t i o n p l a n t was r e p o r t e d t o h a v e s t a r t e d i n 1975. P a t e n t s c l a i m i n g b o t h f o o d a n d i n d u s t r i a l a p p l i c a t i o n s have been f i l e d . M i c r o b i a l A l g i n a t e . A l g i n i c a c i d a n d a l g i n a t e s a r e most i m p o r t a n t gums w i t h many a p p l i c a t i o n s i n f o o d , t e x t i l e , pharmac e u t i c a l a n d p a p e r i n d u s t r i e s . P r o d u c t s o b t a i n e d f r o m seaweed v a r y i n b o t h , q u a l i t y and s t r u c t u r e . S e v e r a l m i c r o o r g a n i s m s produce m i c r o b i a l a l g i n a t e s v e r y s i m i l a r t o a l g a l a l g i n a t e . The c o m p o s i t i o n o f t h e s e p o l y m e r s f o r m e d i s r e p o r t e d t o b e u n e f f e c t e d by t h e c a r b o h y d r a t e source used, and o f c o n s t a n t quality. Most o f t h e main development i n m i c r o b i a l a l g i n a t e s has b e e n c l a i m e d b y T a t e a n d L y l e . Curdlan. C u r d l a n h a s b e e n d e v e l o p e d b y t h e T a k e d a Company i n Japan from a c h e m i c a l mutant o f A l c a l i g e n e s f a e c a l i s v a r myxogenes IOCS. I t s i n d u s t r i a l d e v e l o p m e n t depends o n t h e g e l s t r e n g t h o f h i g h s e t g e l s n o t r e v e r t i n g g r e a t l y when c o o l e d . Aqueous s u s p e n s i o n s o f t h e p o l y m e r r e m a i n s o f t and r e s i l i e n t when c o o l e d , a f t e r h e a t i n g . A p p l i c a t i o n s a r e i m m o b i l i z e d enzymes a s w e l l a s b e i n g u s e d i n p r e p a r a t i o n o f f i l m s and g e l . E r w i n a ( Z a n f l o ) . E r w i n a was d e v e l o p e d b y t h e K e l c o Company s p e c i a l l y f o r c a r p e t p r i n t i n g a p p l i c a t i o n s , due t o i t s c o m p a t i b i l i t y t o c a t i o n i c dyes. I t i s produced from a s t r a i n o f Erwina t a h i t i c a . I t has been c l a i m e d t h a t t h i s p o l y s a c c h a r i d e possesses p s e u d o p l a s t i c i t y , pH s t a b i l i t y and f r e e z e - t h a w s t a b i l i t y . The e x c e l l e n t r e s i s t a n c e t o enzyme a t t a c k , a n d i t s f l o w and l e v e l l i n g q u a l i t i e s h a v e a l r e a d y made i t f i n d a p p l i c a t i o n in thepaint industry.



22.

WELLS

Extracellular

Microbial

Polysaccharides

307

INDUSTRIAL DEVELOPMENT OF MICROBIAL POLYSACCHARIDES. D e x t r a n was f i r s t p r o d u c e d c o m m e r c i a l l y i n Sweden i n t h e e a r l y f o r t i e s , t h e n l a t e r i n E n g l a n d , Canada and t h e U n i t e d States. X a n t h a n was f i r s t p r o d u c e d c o m m e r c i a l l y i n t h e U n i t e d States i nthe early s i x t i e s f o r i n d u s t r i a l applications. I n 1969 FDA c l e a r e d t h e g e n e r a l u s e o f x a n t h a n gum i n f o o d s where t h e s t a n d a r d s o f i d e n t i t y do n o t p r e c l u d e i t s u s e . I n 1973 FDA a l l o w e d u s e s i n p r o c e s s a n d cream c h e e s e s a s a t h i c k e n i n g and s t a b i l i z i n g a g e n t . I n 1974 MID/PID I n s p e c t i o n D i v i s i o n o f USDA i n c l u d e d x a n t h a n gums o n t h e i r a u t h o r i z e d l i s t o f n o n meat i n g r e d i e n t s . One c a n c o n v e n i e n t l y d i v i d e up t h e m a i n m a r k e t d e v e l o p ment o f m i c r o b i a l gums i n t o t h r e e g r o u p s : - Food a p p l i c a t i o n s - P e t r o l e u m and o i l i n d u s t r y a p p l i c a t i o n s - Other a p p l i c a t i o n s . Food A p p l i c a t i o n s . Over 60% o f m i c r o b i a l p o l y s a c c h a r i d e s s a l e s go t o t h e f o o d i n d u s t r y . I n 1975, K e l c o Company a r e s a i d t o have s o l d o v e r 5 m i l l i o n pounds o f x a n t h a n gums i n t o t h e US f o o d i n d u s t r y . X a n t h a n gums have g a i n e d r a p i d acceptance i n t o t h e U n i t e d S t a t e s f o o d i n d u s t r y a n d a p p l i c a t i o n s a r e now b e i n g d e v e l o p e d i n b o t h E u r o p e a n d J a p a n . Denmark, E n g l a n d , I r e l a n d , H o l l a n d , S p a i n a n d Canada h a v e g i v e n r e g u l a t o r y a p p r o v a l . A p p r o v a l s i n F r a n c e , Sweden a n d B e l g i u m a r e e x p e c t e d b e f o r e t h e end o f 1976. I n i t i a l l y the applications followed i n the United States f o r u s e i n s a l a d d r e s s i n g s , meat a n a l o g s , p e t f o o d , b a k e r y p r o d u c t s , c a r b o n a t e d b e v e r a g e s a n d f r o z e n f o o d s w i l l be s t u d i e d . New d e v e l o p m e n t s b y t h e USDA, announced d u r i n g 1 9 7 5 , f o r p r o d u c i n g m a t r i x t e x t u r e s f o r f o o d s and s n a c k f o o d s c o u l d open up v e r y l a r g e d e v e l o p m e n t s . J o i n t p a t e n t s b e t w e e n K e l c o Company and DCA g i v e p r o m i s e o f c h a n g e s i n t h e b a k e r y i n d u s t r y . I t i s r e p o r t e d t h a t a j o i n t - v e n t u r e i n Japan w i t h t h i s group and N i s s h i n F l o u r c o u l d open p o t e n t i a l m a r k e t s i n d o n u t s , o n i o n r i n g p r o c e s s i n g , s n a c k i t e m s a n d c e r t a i n new b a k e r y p r o d u c t s . I n o r d e r t o s e e how t h e s e m i c r o b i a l p o l y s a c c h a r i d e s f i t i n t o t h e o v e r a l l m a r k e t i t i s n e c e s s a r y t o s t u d y t h e t o t a l US c o n s u m p t i o n o f gums i n 1 9 7 5 , w h i c h i s g i v e n i n T a b l e V I . ( X a n t h a n w i t h US s a l e s o f 2,500 t o n s i s c l a s s i f i e d a s a n a t u r a l product. I n i t i a l l y x a n t h a n gums h a v e o b t a i n e d t h e i r m a i n m a r k e t s by r e p l a c i n g gum t r a g a c a n t h . However t h i s m a r k e t h a s p r a c t i c a l l y d i s a p p e a r e d i n t h e US. Though t h e r e e x i s t s s e v e r a l t h o u s a n d tons p o t e n t i a l elsewhere. The w o r l d m a r k e t f o r a l g i n a t e s i s o v e r 17,000 t o n s w i t h about f i v e thousand tons u t i l i z e d i n t h e food i n d u s t r y . About 2,000 t o n s a r e u s e d i n t h e U n i t e d S t a t e s and n e a r l y 1,500 t o n s i n Europe. L a r g e s t a p p l i c a t i o n s a r e i n d a i r y and bakery p r o d u c t s , where c o n s u m p t i o n i s e x p e c t e d t o expand. T h i s c o u l d



308

TABLE V I US CONSUMPTION OF HYDROCOLLOIDS IN FOODS IN Thousand tons


Product

1975 Million dollars

Natural products Starch derivatives Seaweed e x t r a c t s Tree exudates Seed e x t r a c t s Cellulose derivatives

20.5 124.2 4.1 1.4 5.9 5.9

113 64 19 7 10 12

TOTAL

162.0

225

Source:

James H i c k e y - C . H . K l i n e

and Company I n c .

open e x c e l l e n t m a r k e t s t o m i c r o b i a l a l g i n a t e s i f t h e y c o u l d be produced at e q u i v a l e n t p r i c e s t o the a l g a l product. In g e n e r a l the shortages of n a t u r a l l y o c c u r r i n g hydroc o l l o i d s i n 1974 showed t h e v u l n e r a b i l i t y o f t h i s m a r k e t t o l e s s c o s t l y m a n u f a c t u r e d gums. I n g e n e r a l t h e m a i n f o o d p r o c e s s o r s w i l l t e n d t o p r e f e r t o f o r m u l a t e w i t h t h e s e manuf a c t u r e d gums, whose s u p p l y , q u a l i t y and p r i c e a r e n o t s u b j e c t t o v a g a r a n c i e s o f s u p p l y , w e a t h e r , p o l i t i c s and l a b o u r c o s t s . The E u r o p e a n and J a p a n e s e m a r k e t s a r e e x p e c t e d t o o f f e r l a r g e p o t e n t i a l f o r d e v e l o p m e n t . I t must be remembered t h a t o v e r 17,000 t o n s o f x a n t h a n w i l l be a v a i l a b l e p e r y e a r a f t e r 1978 and o v e r h a l f o f t h i s must be a b s o r b e d by t h e F o o d I n d u s t r y . Hence t h e m a i n m a r k e t i n g e f f o r t s o f x a n t h a n must n e c e s s a r i l y move t o E u r o p e . P r o b a b l y a d i f f e r e n t r a n g e o f a p p l i c a t i o n s w i l l e v e n t u a l l y d o m i n a t e o u t s i d e t h e US s i n c e use o f s a l a d d r e s s i n g s , meat a n a l o g s , and c a r b o n a t e d b e v e r a g e s i s n o t so d e v e l o p e d . F o r example f r u i t y o g h o u r t m a r k e t s a r e many t i m e s l a r g e r t h a n i n t h e US. The l a r g e s t E u r o p e a n h y d r o c o l l o i d f o o d u s a g e i s i n t h e m o d i f i e d s t a r c h f i e l d . O v e r 150,000 t o n s u s a g e has b e e n r e p o r t e d t o be u s e d i n t h e E u r o p e a n Community. P r o b a b l y t h e b e s t g r o w t h r a t e comes f r o m c e l l u l o s e dérivâtes. CMC a t 60 c e n t s p e r pound has made g r e a t i n r o a d s i n t o t h e s e e d gum m a r k e t . L a r g e v o l u m e s o f CMC a r e r e p o r t e d t o be g o i n g i n t o i n s t a n t soups and c a k e m i x e s , a m a r k e t t h a t x a n t h a n i s also t r y i n g to penetrate. I n summary t h e f o o d i n g r e d i e n t s m a r k e t i s v e r y c o m p l i c a t e d and o n l y t h e most t e c h n i c a l l y c o m p e t e n t and t e c h n i c a l l y m a r k e t ed o r i e n t e d w i l l s u r v i v e . To s e l l gums i n t o new f o o d p r o d u c t s demands a s o p h i s t i c a t e d t e c h n i c a l i n p u t . I t i s e s s e n t i a l t o u n d e r s t a n d p o t e n t i a l a p p l i c a t i o n . Gums a r e m u l t i f u n c t i o n a l . X a n t h a n added t o r e p l a c e an e m u l s i f i e r , w i l l a l s o i n c r e a s e viscosity. T h i s can c a u s e p r o b l e m s i f t h e o t h e r t h i c k e n e r s a r e not reduced.



22.

WELLS

Extracellular

Microbial

Polysaccharides

309

Petroleum and O i l I n d u s t r y A p p l i c a t i o n s . Polymers a r e f i n d i n g i n c r e a s i n g usage i n the o i l i n d u s t r y and developments a r e f o r e c a s t w h i c h c o u l d open u n l i m i t e d p o t e n t i a l . A t t h i s t i m e the market remains i n e x p l o r a t i o n usage. Market developments h e r e h a s b e e n d i v i d e d i n t o two s e g m e n t s : o i l d r i l l i n g muds a n d enhanced o i l r e c o v e r y . O i l d r i l l i n g muds. The f o u r m a j o r p o l y m e r s i n u s e a t t h i s time are xanthan, p o l y a c r y l a m i d e s , m o d i f i e d s t a r c h e s and c e l l u l o s e d e r i v a t i v e s p a r t i c u l a r l y CMC. D e x t r a n a n d p u l l u l a n a r e a l s o trying to get into this industry. B e c a u s e o f i t s s t a b i l i t y t o pH, h e a t , c a t i o n s a n d d i v a l e n t i o n s coupled t o i t s p s e u d o p l a s t i c behaviour under c o n d i t i o n s o f h i g h s h e a r , x a n t h a n gums a r e t h e t e c h n i c a l l y p r e f e r r e d p o l y m e r for l u b r i c a t i o n o f b e n t o n i t e muds u s e d t o d r i l l o i l w e l l s . D u r i n g 1^75 a b o u t 1,800 t o n s o f x a n t h a n were u s e d i n d r i l l i n g o p e r a t i o n s w i t h a p o t e n t i a l u s a g e o f 3,000 t o n s p r e d i c t e d b y 1980. However r e c e n t p r i c e i n c r e a s e s h a v e c a u s e d s e v e r a l o f t h e m a j o r s t o s w i t c h some o f t h e u s a g e t o CMC e v e n t h o u g h i t t a k e s a l m o s t d o u b l e t h e amount o f CMC t o a c h i e v e t h e same p e r f o r m a n c e effects. X a n t h a n i s a l s o much u s e d i n s u m u l t a n e o u s w a t e r f l o o d i n g and p u s h i n g t e c h n i q u e s u s e d i n t h e N o r t h Sea, where s e a w a t e r c o n t a i n i n g s m a l l q u a n t i t i e s o f x a n t h a n (100 ppm) a r e p u s h e d into injection wells. However, p o l y a c r y l a m i d e s a r e a l s o b e i n g c o n s i d e r e d f o r t h i s a p p l i c a t i o n due t o l o w e r p r i c e . The d r i l l i n g s e r v i c e i n d u s t r y i s c o n t r o l l e d b y a s m a l l number o f s e r v i c e c o m p a n i e s i n c l u d i n g B a r o i d , M i l c h e m , Imco, D r e s s e r i n t h e US w i t h C r o d a and C e c a f r o m E u r o p e . They r e s e l l x a n t h a n o b t a i n e d f r o m K e l c o , G e n e r a l M i l l s o r Rhone Poulenc. Enhanced o i l r e c o v e r y . The g r e a t e s t f u t u r e p o t e n t i a l f o r p o l y s a c c h a r i d e s , l i e s i n enhanced o i l r e c o v e r y . Great i n t e r e s t and r e s e a r c h e f f o r t i s b e i n g c e n t e r e d on r e c o v e r i n g the l a r g e f r a c t i o n o f o r i g i n a l o i l remaining i n p l a c e i n o i l s t r a t a a f t e r c o n v e n t i o n a l r e c o v e r y methods have been u t i l i z e d . A l a r g e i n c e n t i v e f o r d e v e l o p i n g r e c o v e r y enhancement methods e x i s t s i n t h e U n i t e d S t a t e s a s t h e p e r c e n t a g e o f i m p o r t ed o i l f o r d o m e s t i c p u r p o s e s i s i n c r e a s i n g v e r y r a p i d l y . A c c o r d i n g t o the American Petroleum I n s t i t u t e , o f t h e 440 b i l l i o n b a r r e l s o f o i l d i s c o v e r e d i n t h e U n i t e d S t a t e s b y t h e e n d o f 1974, 295.8 b i l l i o n b a r r e l s w o u l d h a v e t o b e r e c o v e r e d b y e n h a n c e d r e c o v e r y , o r a d v a n c e d enhanced r e c o v e r y techniques. I n 1973 t h e G u l f U n i v e r s i t i e s R e s e a r c h C o n s o r t i u m i n a s t u d y w i t h many o f t h e l a r g e o i l c o m p a n i e s s t a r t e d a s e r i e s o f e n h a n c e d r e c o v e r y . I n 1974 v e r y h i g h l y o p t i m i s t i c p r e d i c t i o n s o n s u r f a c t a n t f l o o d i n g gave r i s e t o e s t i m a t e s o f r e c o v e r i n g 500,000 s t o c k t a n k b a r r e l s (STB) p e r day. However s i n c e



310


t h a t t i m e , r e d u c e d e s t i m a t e s and l o n g e r r e a l i z a t i o n t i m e s have been p r e d i c t e d . A t t h e e n d o f 1975, t h e c o n s o r t i u m were p r e d i c t i n g a n n u a l p r o d u c t i o n r a t e s f o r 1985 o f enhanced o i l b e t w e e n 300-400 m i l l i o n STB, w h i c h w o u l d c a l l f o r a n a n n u a l p o l y m e r demand o f b e t w e e n 200-250 m i l l i o n pounds b a s e d o n 5 8 % E0R b y s u r f a c t ant f l o o d i n g . However i n 1976, t h e G u l f C o n s o r t i u m h a s how l o w e r e d i t s 1986 p r e d i c t i o n t o a r e a l i s t i c g o a l o f 200,000 STB p e r d a y , w i t h a s t a r t i n g d a t e f o r l a r g e s c a l e d e v e l o p m e n t i n 1979. Table 7 gives t h e polymer requirements f o r both cases s t u d i e d . T h i s s t u d y h a s assumed t h a t t h e m a r k e t i s e q u a l l y s h a r e d between p o l y s a c c h a r i d e s and p o l y a c r y l a m i d e s . TABLE V I I POLYMER DEMAND FOR ENHANCED O I L RECOVERY (Thousands o f pounds p e r d a y ) Year

Case A

1979 1980 1981 1982 1983 1984 1985 1986

7.3 14.6 32.8 51.1 76.7 11.0 120.5 138.5

Source:

Case Β 18.3 40.2 79.0 131.5 175.2 215.2 233.6 248.2

G u l f U n i v e r s i t i e s R e s e a r c h C o n s o r t i u m , M a r c h 1976 1. P o l y m e r s demand assumed t o b e 5 0 % p o l y s a c c h a r i d e s , 50% p o l y a c r y l a m i d e . 2. C a s e A - assumes d e v e l o p m e n t t o 200,000 STB/day by 1986. C a s e Β - Assumes d e v e l o p m e n t t o 500,000 STB/day by 1986.

Hence t h i s d e l p h i t y p e e x e r c i s e p r e d i c t s m a r k e t s o f b e t w e e n t o 140 t h o u s a n d pounds p o l y m e r demand p e r d a y b y 1986 s t a r t a t b e t w e e n 7,300 t o 18,300 pounds d a i l y i n 1979. A s s u m i n g t h i s p o t e n t i a l t o be c o r r e c t , t h e n e x t p r o b l e m t o be r e s o l v e d b y t h o s e d e v e l o p i n g p o l y s a c c h a r i d e p o l y m e r s , w i l l b e t h e p o t e n t i a l s p l i t b e t w e e n p o l y s a c c h a r i d e and p o l y a c r y l a m i d e s . The d i f f i c u l t y i n p r e d i c t i n g f u t u r e t r e n d s ( a c c o r d i n g t o t h e Gulf Consortium) i s the general d i s s a t i s f a c t i o n w i t h the current generation of materials. P o l y a c r y l a m i d e s a r e i n t h e r i g h t p r i c e range b u t a r e d e s c r i b ed a s u n d u l y s h e a r s e n s i t i v e a n d s a l t s e n s i t i v e . T a b l e V I I I shows d e l p h i a n a l y s i s o f v a r i o u s f i g u r e s d i s c u s s e d i n numerous s t u d i e s s i n c e 1974. 250 ing


22.

Extracellular

WELLS

Microbial

Polysaccharides

311

TABLE V I I I USE OF POLYACRYLAMIDE AND POLYSACCHARIDE FOR EOR Polyacrylamide


Viscosity

thickening

S a l i n i t y maximum o f f l u i d Maximum r e s e r v o i r t e m p e r ature Divalent

i o n maximum

Permeability o i l plugging C o s t t/lb

Polysaccharide

Ideal

10-15 cp a t 10-15 c p a t 20 c p a t 500 ppm 100 ppm 500 ppm 1500-2000 ppm

10000 ppm

15000 ppm

175-200°F

200-225°F

up t o 250°F

200 ppm

5000 ppm

5000 ppm

50-100md

>100 md

2.25+0.30

1.25+2.00

Critical>50md 1.30+0.30

T h i s i s b a s e d o n t h e G u l f C o n s o r t i u m recommend c h a r g e o f 10 pounds o f s u r f a c t a n t s , 3 pounds o f a l c o h o l s a n d a b o u t 1 pound of polymer per b a r r e l . Though t h e u s e o f a l c o h o l i s i n some d o u b t , s i n c e i t may be b e t t e r t o i n c r e a s e t h e s u l p h o n a t e r a t i o a t t h e expense o f t h e alcohol. I t s h o u l d a l s o be p o i n t e d o u t t h a t s u r f a c t a n t f l o o d i n g i s n o t t h e o n l y method o f e n h a n c e d r e c o v e r y . B a s i c r e c o v e r y p r o c e s s e s have b e e n a p p o r t i o n e d a s f o l l o w s : - Surfactant recovery 58% - Thermal recovery 29% - Carbon d i o x i d e processes 8% -Hydrocarbon m i s c i b l e processes 5% A recent development i s s t u d y i n g f e a s i b i l i t y o f d e v e l o p i n g s m a l l s c a l e u n i t s t o produce s u r f a c t a n t charges i n c l u d i n g p o l y s a c c h a r i d e s a t t h e o i l f i e l d s i t e . I t has been n o t e d t h a t EOR h a s s t i l l many t e c h n i c a l p r o b l e m s t o s o l v e b e f o r e i t w i l l be a c o m m e r c i a l r e a l i t y . However t h e i n c r e a s i n g f i n a n c i a l s u p p o r t by Energy R e s e a r c h and Development A d m i n i s t r a t i o n i s most w e l l c o m e a n d i n d i c a t e s p o l i t i c a l b a c k i n g w h i c h i s e s s e n t i a l t o make t h i s d e v e l o p m e n t a r e a l i t y . O t h e r A p p l i c a t i o n s . The o t h e r a p p l i c a t i o n s o f m i c r o b i a l p o l y s a c c h a r i d e s h a v e come f r o m t a k i n g t h e m a r k e t o f t h e n a t u r a l p l a n t gums w i t h more r e l i a b l e o r t a i l o r made p r o d u c t s . Z a n f l o has o b v i o u s l y been developed f o r p a i n t and d y i n g applications. Other p o l y s a c c h a r i d e s have found markets i n t e x t i l e s , c o s m e t i c s , p h a r m a c e u t i c a l s and l i q u i d f e e d s . S e v e r a l p a t e n t s have r e c e n t l y been i s s u e d i n Japan f o r p r o d u c t a p p l i cations i n anticancer preparations. The i n d u s t r i a l u s e s a r e more c o m p l i c a t e d t h a n f o o d u s e s and a r e due t o r h e o l o g i c a l p r o p e r t i e s a n d w i d e r a n g e s o f s t a b i l i t y and c o m p a t a b i l i t y w i t h c o n v e n t i o n a l t i c k e n i n g agents and s u r f a c e a c t i v e a g e n t s .


312



The s y n e r g i s t i c e f f e c t s o f x a n t h a n w i t h l o c u s t bean gums is well exploited. However o n a c c o u n t o f t h e c o m p l e x i t y , most o f t h i s know-how r e m a i n s t h e c o n f i d e n t i a l p r o p e r t y o f t h e p r o c e s s o r and s u p p l i e r o f t h e gum. CONCLUSION T h i s paper has t r i e d t o e s t a b l i s h t h e p l a c e o f m i c r o b i a l l y p r o d u c e d gums i n a n e x p a n d i n g i n d u s t r i a l gum m a r k e t . I t i s c l e a r t h a t x a n t h a n gum p r o d u c t i o n w i l l r e m a i n a t a p l a t e a u u n t i l t h e the new p r o d u c t coming i n t o p r o d u c t i o n i s a b s o r b e d . The w h o l e i n d u s t r y r e q u i r e s a v e r y h i g h l e v e l o f t e c h n i c a l e x p e r t i s e and m a r k e t i n g s k i l l t o d e v e l o p i n d u s t r i a l u s a g e . The f u t u r e l a r g e p o t e n t i a l s i n enhanced o i l r e c o v e r y a r e s t i l l a l o n g way o f f a n d much d e v e l o p m e n t work w i l l b e r e q u i r e d b y b o t h the o i l p r o d u c e r s a n d p o l y m e r s u p p l i e r s t o make t h i s a commercial reality. P r o d u c t i o n problems o f f e r m e n t a t i o n d r y i n g and r e c o n s t i t u t i n g d i l u t e s o l u t i o n must be s o l v e d . On a c c o u n t o f t h e l a r g e d e v e l o p m e n t c o s t s n e c e s s a r y f o r b o t h t e c h n i c a l a n d m a r k e t d e v e l o p m e n t i t must b e c o n c l u d e d t h a t o n l y companies d e v e l o p i n g whole range o f m i c r o b i a l p r o d u c t s w i l l predominate. APPENDIX "A" BIOPOLYMER CAPACITY SUMMARY ( M a i n l y Xanthan) tons/year) Date

Capacity

Company

Affiliates

Location

KELCO

Merck subsidiary

San Diego

KELCO

Merck subsidiary

Oklahoma

10,000

End 1976

BIOSYNTHESEMELLE

Rhone P o u l e n c Melle General M i l l s (France)

2,000

Existing

GENERAL MILLS

Rhone P o u l e n c

Iowa

2,500

Mid

TATE & LYLE

Hercules Inc.

NA°

NA°

NA°

TATE & LYLE

Hercules Inc.

NA°

NA°

NA°

T o t a l known c a p a c i t y b y end 1979

3,500

x

Existing

1977

18,000+ M e t r i c

Tons

E s t i m a t e d " c o n v e n t i o n a l " m a r k e t s b y end 1979 15-16,000 M Tons x B e i n g expanded t o 5 , 0 0 0 t / y r b u t i n c l u d e s d e v e l o p m e n t facilities. ° NA = n o t announced.



22.

WELLS

Extracellular

Microbial

Polysaccharides

313

BIBLIOGRAPHY A r n o l d C.W, " C h e m i c a l C h a l l e n g e s i n t h e Q u e s t f o r E n h a n c e d O i l R e c o v e r y " - A m e r i c a n C h e m i c a l S o c i e t y ( A p r i l 4-9 1976). G o g a r t y W.B. " S t a t u s o f S u r f a c t a n t o r M i c e l l a r Methods S.P.E." N a t i o n a l M e e t i n g , D a l l a s , T e x a s ( S e p t . 28 - O c t . 1 1975). H i c k e y J.R. " T h i c k e n e r s a n d S t a b i l i z e r s f o r F o o d ECMRA M e e t i n g of M a r k e t " - Development A n a l y s t s M e e t i n g , London ( A p r i l 1976). K a n g K . S . a n d K o v a c s P. " I n t . C o n g r e s s o f F o o d S c i e n c e " M a d r i d (1974). J e a n e s A. "Food T e c h n o l o g y " (May 1974) 34-39. K e l c o Company " T e c h n i c a l B u l l e t i n DB 2 1 " (1971) K i m u r a H. " A b s t r a c t 3 2 " I n s t i t u t e o f F o o d T e c h n o l o g i s t s M e e t i n g M i n n e a p o l i s (1972). Lawson J . , S u t h e r l a n d I.W. " P o l y s a c c h a r i d e s f r o m M i c r o o r g a n i s m s i n Economic M i c r o b i o l o g y ; ed. by A.H. Rose - A c a d e m i c P r e s s ( i n p r e s s ) . " M a r k e t i n g o f P r i n c i p l e W a t e r S o l u b l e Gums i n P r o d u c i n g C o u n t r i e s " I n t e r n a t i o n a l T r a d e C e n t e r , Geneva ( 1 9 7 2 ) . N a y l o r J . " P r o d u c t i o n Trade and U t i l i z a t i o n o f Seaveeds and Seaweed P r o d u c t s " FAO, Rome ( 1 9 7 6 ) . " R e p o r t o n C h e m i c a l Demand and S u p p l y S t u d y " . " R e l a t i n g on M i c r o e m u l s i o n F l o o d i n g G u l f U n i v e r s i t i e s Research C o n s o r t i u m " Houston, Texas (March 26, 1976). S h a r p J.M. "The p o t e n t i a l o f E n h a n c e d R e c o v e r y P r o c e s s e s " S.P.E. M e e t i n g D a l l a s , T e x a s ( S e p t . 2 8 - O c t . 1 1975) Umland C.W. " P r e s e n t a t i o n f o r F e d e r a l E n e r g y A d m i n i s t r a t i o n " E n h a n c e d O i l and Gas R e c o v e r y Symposium, W a s h i n g t o n (Dec. 1 9 7 5 ) . W h i s t l e r R.L. " I n d u s t r i a l Gums" 2nd E d i t i o n A c a d e m i c P r e s s , New Y o r k ( 1 9 7 3 ) .


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