FERMENTATION icultural and Food Chemistry at the 116th Presented before the Division of Meeting of the American Chemica Society, Atlantic City, N. J., September 1949
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Factors Affecting Production of Penicillin in Semi-Pilot Plant Equipment W. E. BROWN' AND W. H. PETERSON Uniueraity of Wisconain, Madison, Wis.
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High-yielding penicillin fermentations have been obHE s t u d y of t h e mentors described by Stefstained in a 30-liter laboratory fermentor that simulates niak et al. (18). Although factors i n f I u enc i n g the conditions of industrial production. Good fermentanot so many fermentations p e n i c i l l i n production by tions are characterized by rapid production Of mycelium, can be run in 30-liter fersubmerged culture has resteady utilization of lactose, and maintenance of proper mentors aa in flasks, the ceived a great deal of attenpH conditione for a long period of time. Adequate aeraresults are more closely tion in recent years. Howtion is important in fermentations of this type, and is a related to large scale proever, since the advent of function of both rate of aeration and degree of agitation. duction than are flask runs. the high-yielding wide 1y Optimal conditions were 0.64 liter of air per liter of medium In the present study the used i n d u s t r i a l c u l t u r e per minute, and agitation at approximately 580 r.p.m. effects of aeration and agiPenicillium c h r y sogenum Steady utilization of lactose was associated with a satisQ176 ( I ) , research published tation, pH c o n t r o l , a n d factory pH (6.8 to 7.4), but often fermentations occurred on its use in the pilot plant addition of p h e n y l a c e t i c in which the various metabolic activities were not in balhas been limited. acid were investigated. ance. For the regulation of such fermentations manual The construction, Qperaor automatic pH control proved valuable. Correct use of tion, and performance of FERMENTATION precursor is another important factor related to penicillin 1Wgallon fermentors has EQUIPMENT production. Addition of 0.05% phenylacetic acid every 12 been described by Stefaniak Thirty-liter fermentors of hours during the fermentation resulted in maximum foret al. (18,17). Maximum t h e t y p e described b y Rivett et al. (1.8)have been mation of penicillin G. Under the best conditions of yields were obtained in 65 modified to provide autooperation 1800 units of penicillin per ml. were obtained, to 72 hours a t 23 O to 29" C. matic defoaminq and Of total penicillin, approximately 97% was penicillin G. on various modifications of control. A dramng of the corn steep-lactose type of fermentor is given in Fimre 1. Borosilicate alass m e d i u m of M o v e r a n d battery jars, 12 X 18 inches, were usedin the early ex erigents Coghill (11). The yield of penicillin varied greatly with , On the effect Of aeration and agitatiqn. Subsequent Fermentsmedium, and rate of aeration. Strain ~ 1 7 6 which tions were run in stainleas steel con;tainersbecause they allowed averaged 761 units of penicillin Per ml., gave the highest yields better temperature control and molded the excessive breakage ( 4 ) . The addition of phenylacetic acid to the medium further cost incurred with lass vessels. Steel containers havjrig the same dimensions as t i e glass jars were made of 16-gage stainlesa increased the yield to 1000 units per ml. (6). Gordon et al. ( 6 ) described the construction and operation of B ~ ~ ~ ~ h ~ ~ ~ ~i n (~ $ ~ ~ s ~ 50-gallon fermentation vessel for use in microbiological research. holes in the lid of the fermentor. The two parts of the fermentor Yields of 400 to 500 units of penicillin per ml. were obtained with were bolted together with a rubber gasket */,a inch thick, 80 aa to ensure a tight seal. The metal frame required with the glass culture 8176 in a Corn steep medium containing 0.25 P a m per jars was not needed when the steel containers were used. liter of phenylacetamide as penicillin precursor. Only the parts inside the fermentor were made of stainless steel. While a yield of 1000 units of pencillin per ml. is high as judged Air entered the fermentor through filter A and ring sparger B. by previous standards, there ie no reason to assume that i t is The sparger waa 6.75 inches in diameter and had six '/ninch holea Mounted immein the ring. Air left the fermentor by outlet maximal. By modifying various factors that affect the f e r m e n h diatel above the sparger on a 24 X 0 5 inch shaft was a fourtion, yields to l8OO per ml*have been Obtained blade$ propel]er, D,of an dia&ter of 8.5 inches. The ently. Thirty-liter fermentors were used, because they Offered blades were 1 x 2 inches and were set a t an angle of 30" to the greater scope for experimentation than did the 100-gallon ferhorimntal, 90 that the medium was thrown upward. The agitator waa operated by a belt revolving on pulley E. Coning of the liquid 1 Preaent addreas, Merck k Co., Ltd., Valley5eld, Que., Canada.
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