unit they envision will consist of a cylin drical tank about 100 feet high and 20 feet in diameter. Injected air will be blended with the separately pumped sludge/water i(Ο mixture. A system of guidelines, similar ΖLU to those used in fermenters, will promote 00Ο circulation within the vessels. Aeration and sludge separation will be integrated within the one unit. Design and develop ment likely will cost $1 million before this second-generation wastewater biotreatment unit reaches the commercialization stage, Trobisch estimates. D
1
Single-cell protein pilot unit starts up Single-cell protein (SCP) is being pro duced in pilot-plant quantities in a new facility that Hoechst started up late last month at its chemical complex outside Frankfurt, West Germany. The 1000 metric-ton-per-year operation, developed by Hoechst and its engineering subsid iary, Uhde, with financial support from the West German ministry of research, involves specially designed continuous fermenter vessels and new technology (C&EN, April 24, page 18). Product will be offered as an animal feed supplement. A modification of the product might be suitable for human use. A decision whether to move into full-scale commercial production will await the outcome of the current round of evalua tions, which will take more than two years. However, Hoechst is prepared to license its process technology and knowhow to other companies that may be in terested. Methylomonas clara, the bacterium involved, is grown on a mixture of air and methanol containing ammonia, water, and other essential mineral nutrients. The dried product, which Hoechst tradenames Probion, contains some 70% protein, 10% nucleic acids, 8% fats, 7% mineral "ash," and 5% water. A purified version, from which essentially all the nucleic acids and fats have been removed, has a protein content of more than 90%, with minerals and water making up the balance. Called Probion-S, Hoechst expects this to be acceptable for human consumption. Its preparation entails new solubilizing and extraction methods for which the com pany has applied for patents. The development emerged from a broader research program in the general area of biotechnology that Hoechst has been engaged in since 1971 and for which the West German government is con tributing about $30 million. The new pilot plant cost nearly $10 million, with the research ministry footing 67% of the bill. The plant consists of two stainless steel fermentation vessels, each more than 65 feet high and each with a volume of more than 700 cu ft. Each can produce up to 1000 metric tons per year of product. "Having two fermenters that can be op erated independently . . . leads to flexi bility in our studies," points out Dr. Uwe 20
C&EN May 15, 1978
Faust: technique is superior
Faust, who supervises the pilot plant op erations. Product from the fermenters goes to a concentration unit. There, mechanical dewatering is aided by electrochemical coagulation. The concentrated material then passes on to a spray dryer. Liquid separated during the dewatering step is sterilized and recirculated to the reaction vessels. To make Probion-S, the SCP product first is dissolved at room temperature in a mixture of anhydrous ammonia and methanol. This breaks down its cellular structure and dissoves the liberated fat content. Filtration removes the fatty fraction leaving a homogenate of protein and nucleic acids. These are water soluble and can be separated from the protein by a simple washing step. This novel purification technique may be applied to protein preparations from any source, Faust says. It is superior to
conventional methods that have been in use until now, he adds. It avoids the use of alkaline treatment that can cause free amino acids to link together to form dipeptides like lysinoalanine, some of which have toxic effects. It is important that proteins for human consumption be free from nucleic acids, Faust continues, because these can pro mote development of undesirable physi ological conditions such as gout. Pro bion-S could find outlets in nutritive products like bakery goods, sausages, meat pastes, and soups, he believes. Pro viding protein concentrate to human diets is more sensible than adding it to animal feed, according to Faust, because about four fifths of it is lost in the animal's di gestive tract. Yet another extension of the current work involves partial hydrolysis of the protein to a soluble form. Hoechst scien tists have devised two methods to do this. One, using chemicals, still is under wraps. The other is a more expensive enzymic method. The soluble oligopeptides com prising 10 to 100 peptide units, precipitate in an acid medium. By use of appropriate exclusion nozzles, sheets or fibers of pro tein may be produced. The technique might be used for making sausage casings, texturized meatlike products, and other items for which there are potentially siz able markets. The conditions of hydrol ysis have been chosen carefully to avoid formation of certain peptides undesirable in foods because they have a bitter taste. Because of the extent of demand, arti ficially produced SCP will never fully re place soybean protein in animal feed, Faust says. Nevertheless, that they can be produced probably will tend to have a stabilizing influence on prices, which can fluctuate widely depending on the avail ability of soybeans. G
Gibbs Medal
Baker honored for widespread accomplishments Dr. William O. Baker, a chemist who made his mark in an electrically oriented company, likes to talk about the part nership between chemistry and electric ity. It's only been 150 years since Faraday first recognized that chemistry and elec tricity were closely associated in nature, he notes, and only 80 years since Thomson first proposed the electron. "It gives me a tremendous lift," he says, "to see that chemistry, based on the ideas of bonding and valency and reactivity through elec trons, has been the source of a major part of the materials for civilization. The ex citing thing—that I think hasn't been fully emphasized yet—is that electricity has done similar things in the same time, with a very high degree of interaction with chemistry." Baker is president of Bell Telephone Laboratories. This week, he will receive
the Willard Gibbs Award for 1978. The prestigious gold medal is awarded annu ally by the Chicago Section of the Amer ican Chemical Society "to publicly rec ognize eminent chemists who, through years of application and devotion, have brought to the world developments that enable everyone to live more comfortably and to understand this world better." The Gibbs Award was founded in 1910 by William A. Converse, a former secre tary and chairman of the Chicago Section. Svante Arrhenius was the first medalist. The roster of recipients includes such other notable names as Leo Baekeland, Marie Curie, Gilbert N. Lewis, and Roger Adams. Medalists are selected by a na tional jury of 12 eminent chemists from different disciplines. Baker received a Ph.D. degree in physical chemistry from Princeton in
