Showing papers on "Solid-state fermentation published in 1990"

Production of bacterial thermostable alpha-amylase by solid-state fermentation: a potential tool for achieving economy in enzyme production and starch hydrolysis.

Abstract: Publisher Summary This chapter discusses the production of bacterial thermostable α amylase by solid-state fermentation. Bacterial thermostable α-amylase (1,4-α D glucan glucanohydrolase), one of the enzymes used in saccharification of starch, randomly attacks α-D- glucosidic linkages in starch thereby leading to the production of limit dextrins. α-amylase an industrially important enzyme produced in higher quantities and represents ∼12% of the sales value of the world market for enzymes. In addition to its use in starch-processing industries, the ability of α-amylase to cause midchain random degradation of starch has been of vital importance to several other industries. This chapter analyzes various possible modes for reducing the cost of starch hydrolysis. It also establishes that the liquefaction and partial saccharification of starch by bacterial thermostable α-amylase is one of the most cost intensive unit operations, chiefly because of the cost of the enzyme. In addition, it identifies the potential of the solid-state fermentation (SSF) technique for reducing the cost of producing bacterial thermostable α-amylase and reviews the literature on its production using the SSF process.

Critical importance of moisture content of the medium in alpha-amylase production by Bacillus licheniformis M27 in a solid-state fermentation system

Abstract: A large reduction (about 30%–78%) is observed in the production of alpha-amylase by Bacillus licheniformis M27 in standardized wheat bran medium under solid-state fermentation when the moisture content of the medium is higher than the standardized value (65%). However, a surge in enzyme production in the first 24 h of fermentation is observed in media with 75% and 85% moisture. The role of decreased oxygen transfer in reducing enzyme tires by about 78% in the medium containing 95% moisture is evident, since the enzyme tire can be effectively increased by agitating the medium during fermentation. No such limitation in oxygen transfer is evident in medium containing 65% moisture even where incubated under static conditions or when the flask is capped by aluminum foil. The data indicate the critical importance of the moisture content of the medium in α-amylase production by B. licheniformis M27 in solid-state fermentation systems. The results also have several implications of scientific and techno-economic importance and are useful in explaining some of the advantages of a solid-state fermentation system over the submerged fermentation process.

Production of fungal rennet by Mucor miehei using solid state fermentation

Abstract: Investigations have been carried out on the production of fungal rennet using a thermophilic strain ofMucor miehei under solid state fermentation conditions. A high milk clotting enzyme activity (58000 Soxhlet units/g) was achieved when optimum conditions were used. Further, a high ratio of 6.6:1 between milk clotting and proteolytic activities for this enzyme was obtained. Cheese prepared using this enzyme was also found to be acceptable in organoleptic quality. Large scale production of the enzyme in trays using the optimum conditions gave milk-clotting enzyme activities comparable to those in flask experiments.

Oxytetracycline production by Streptomyces rimosus in solid state fermentation of sweet potato residue.

Abstract: Sweet potato residue, a starchy agricultural waste, was used as a substrate to produce oxytetracycline byStreptomyces rimosus TM-55 in a solid-state fermentation. Oxytetracycline was detected on the third day, reached its maximum value on the sixth day and remained constant to the twentieth day. Optimal conditions for oxytetracycline production were an initial pH of 5.5 to 6.5, supplemented with 20% (w/v) defatted roasted peanut meal, as the sole nitrogen source, 1.0% (w/v) CaCO3 and 2.0% (w/v) MgSO4·7H2O, being incubated at 26 to 35°C for 6 to 7 days. Oxytetracycline reached 12.1 mg/g substrate.

Mode of growth ofRhizopus oligosporus on a model substrate in solid-state fermentation.

Abstract: The growth ofRhizopus oligosporus on a model solid substrate consisting of cassava starch and other nutrients embedded in a kappa-carrageenan matrix was followed microscoplcally. There were two distinct growth phases: (1) germination of spores and development of mycellum to form a loose network over the whole substrate surface; (2) increase in the density of the mycellum. Although some penetrative hyphae were produced, the biomass was malnly restricted to the surface. Consequently, starch utilization was greatest near the surface. Based on these observations a descriptive model for the growth ofRhizopus ollgosporus on the model substrate was proposed. The five steps are: (1) release of glucoamylase by the mycelium; (2) diffusion of the glucoamylase to the starch; (3) hydrolysis of the starch by the glucoamylase, releasing glucose; (4) diffusion of glucose; (5) absorption of glucose by the mycellum at the surface to produce new blomass.

Characteristics and Novel Features of Thermostable α‐Amylase Produced by Bacillus licheniformis M27 under Solid State Fermentation

Abstract: The purified α-amylase from Bacillus licheniformis M27, produced under solid state fermentation technique, showed novel characteristics as compared to those reported by other workers for the purified α-amylases from B. licheniformis obtained by submerged fermentation process. Some of the novel features of the characteristics of the enzyme from B. licheniformis M27 include two peaks for pH optima at 6.5–7.0 and 8.5–9.0, gradual loss of activity to about 86% between pH 7.0–7.5 followed by rise to full activity between 7.5–8.5, temperature optimum at 85–90°C at pH 7.0 and 9.0, sharp fall in stability at acidic pH values and the thermostability response which is more similar to the enzyme from other species of Bacillus. The moleculuar weight of the enzyme was found to be 19,500 ± 500 and 56,000 ± 2,000 when determined by gel filtration and SDS PAGE, respectively. The activation energy is 20.4 times lower than that reported for the enzyme from another strain of B. licheniformis. It also showed differences in the contents of amino acids such as serine, proline and methionine.

Effect of nutrition variables on solid state alcoholic fermentation of apple pomace by yeasts.

Abstract: The fermentation of apple pomace to ethanol via solid state fermentation has been studied using Saccharomyces cerevisiae, S. diastaticus, Pichia fermentans, Candida utilis and C tropicalis. The effect of nitrogen, phosphate and trace elements has been compared in selected strains (S cerevisiae T2 and S diastaticus) on the basis of the fermentation efficiency of apple pomace. An improvement in fermentation efficiency was observed with both the strains on adding various phosphates, nitrogen sources or trace elements. However, the extent of stimulation in most cases was higher when the test strain was S diastaticus.

Bioconversion of lignocellulosic materials raised from saline land for production of biofuels using cellulomonas species (as cellulolytic organisms)

Abstract: Different species belonging to the genus Cellulomonas namely C. biazotea, C. cellusea, C. fimi and C. flavigena, previously isolated in these laboratories , were screened for production of celluloytic enzymes in both solid and aqueous media containing various cellulosic substrates. Six basic parameters were used to evaluated the organisms; growth on solid media ; growth in aqueous culture media to product celluslases; resistance of the cellulases/ xylanases to end-product inhibition; thermal stability of the enzymes; ability of the organisms for enhanced production of cellulases and xylanases with changes in the growth conditions and saccharification efficiency. All strains grew rapidly on defined media containing carboxymethly cellulose –Na salt (CMC), esculin, sigmacell 100 or cellobiose in the presence or absence of glucose. The criteria used is based on the secretion of enzymes namely CMCcase, I²-glucosidase and Avicelase (Sigmacellase) and cellobiase. These studies and liquid culture studies revealed that C. biazotea was the fastest growing and the best producer of theses enzymes. These also showed some resistance to end-product inhibition. Liquid culture screening for production of cellulases and grew rapidly in liquid media and produced cellulases equivalent to or better than those of other well studied celluloytic microbes (1.86 IU FPase/m1). The use of I±-cellulose, filter paper, cotton wool or sigma cell 100 resulted in increased yields of Fpase followed by Kallar grass (Leptochloa fusca L. Kunth) rasied from saline lands, while xylanase activities were detected when Kallar grass was used inducer. FPase, CMCase and xylanase accumulated extracellularly while I²-xylosidase were mainly cell-bound. The greatest enzyme production occurred at 30 oC, pH 7.3 after 3 days of incubation both from realistic cullulosic substrates viz, filter paper I±-cellulose or sigmacell 100 or lignocellulosic substrates . C biazotes was selected as the best producer of enzymes and was studied in greater detail. The enzymes titres were characterized for some of the properties related to saccharification. The standard assay temperature pH were 40oC and 7 respectively. The change in assay temperature and pH changed the activities. The enzyme activities from C. biazotea showed the temperature optima between 35-50oC. The enzyme system was stable at 25 oC for 7 days in the presence of growth substrate. The cullulases and xylanases exhibited a broad PH activity profile; with optimal activity for I²-glucosidase glucosidase and I²-xylosidase in the range of 3-7 while CMCase, FPase and Xylanases activities showed pH optima of 8-7.5. This could be an important attribute from the practical application stand point as pH control would not be as critical as observed with many other cellulose preparations. Another attribute of the cellulose/ xylanase complex was its resistance to end-product inhibition e.g maximum deactivation of FPase, CMCase and I²-glucosidase occurred by 12, 30 and 27 % respectively in the presence of 10 % glucose when exposed for 1 hour. Similar was the effect of cellobiose, xylose or thanol. The enzyme complex was activated by Co. Mn, S, Ca, Mg and Fe and repressed by Hg or Zn salts. The conditions for enzyme production were optimized. In plated tests 0.25% sigmacell 100 for Avicelase production while aqueous culture studies indicated that 1 % carbohydrate concentration in cellulosic or LC substrates was optimum. Yeast extract could not be replaced by peptones or other growth promoters; pH 7.3 and temperature 30oC were found optimum for production of cellulases and xylanases. Dubos salts were found optimum to provide ionic strength ; other media used by other workers to produce these enzymes were not suitable for enhancing production of cellulases and xylanases. Nitrates were the best nitrogen sources and supported greater cell mass and enzyme production. Inoculum size, between 80 and nitrate addition enhanced production of cellulases and hemicelluases. All enzymes were produced from Kallar grass when glucose, glycerol, galactose, lactose, sucrose, cellobiose or sorbose was also present in the liquid medium. The maximum activities of FPase, CMCase, Xylanase, I²-glucosidase and I²-4.6, 16.1, 0.81, 1.45 IU/mg protein respectively. The enzyme system of cellulose complex was produced when C. biazotea was grown on Kallar grass straw in the absence or presence of I± cellulose. Saccharification efficiency was evaluated using I±-cellulose, Kallar grass, wheat straw, bagasse, and CMC-Na salts as substrates. At low substrate concentration(1, 2.5, 5% w/v), near theoretical yields of reducing sugars were obtained. At higher substrate concentration, the saccharification efficiency even with concentrated enzyme filtrates declined. The highest saccharifications were obtained from CMC, wheat straw or bagasse e.g, maximum saccharification from 10% I±-cellusose, Kallar grass, wheat straw, bagasse and CMC was 30, 39, 71 69 and 65% respectively and from 12.5%, this was 28, 39, 59, 57 and 51. Apparently cellulase titres from C. biozotes better saccharified wheat straw or bagasse and liberated sugars were fermented to ethanol with Saccharomyces carlsbergensis. Concentrated enzyme filtrates gave a maximum of 85% theoretical yield of ethanol compared to 96 % obtained from glucose. Whole culture filtrates also saccharified 5% wheat straw or bagasse suspensions and the hydrolyaates were fermentable to yield alcohol with a maximum theoretical yield of 65 % . Trichoderma spp namely T. reesei and T. harzianum were tested for their abilities to produce cellulases from Kallar grass straw, P. maximum, wheat straw or bagasses in the presence or absence of I±- cellulose, I±- cellulose induced cellulases in. greater quantity followed by Kallar grass plus I±- cellulose The enzyme filtrates produced from the latter treatment were used for saccharification and fermentation studies to produce ethanol. The cellulase titres both from T. harzianum and T. reesei saccharified 5 % (alkali-treated ) Kallar grass and P. maximum Saccharified carried out at 50oC gave 85-96 % theoretical yield of sugar calculated on the basis of total carbohydrates present in the substrates whereas saccharfication at 40 oC released 77-91% sugars, P maxium produced more glucose compared against that from Kallar grass. Sugars from Kallar grasshdrolysate, produced with both the enzyme preparations. 10 % substrate suspension was saccharified with concentrated cellulase titres obtained in solid state fermentation and liberated sugars were fermented to ethanol with yeast with appreciable theoretical yield 987-98). Micro-organisms have the ability to grow on inexpensive cellulosic agricultural residue/ wastes to produce protein of high biological value for feeding livestock and ruminants. Thus to establish optimum condition of pH, ionic concentration of growth medium, nitrogen source, temperature, substrate, substrate concentration, substrate treatment and carbon and nitrogen ratio for maximum production of mycelial cell protein and mycelial biomass form Kallar grass (found to be a strong induce of cell mass biosynthesis among 14 different carbon sources) through fermentation with C. biazotea (found to be high cell mass produce among four different strains of Cellulomonas) has been attempted. The optimum conditions determined as above were applied to ferment Kallar grass in fed-batch culture studies to produce SCP in a fermentor to have it in large quantity. The biomass obtained was then analysed for proximate composition to find the profile of essential amino acids in pure culture of Cellulomonas or Cellulomonas S. uvarum. The chemical analysis indicted that all essential amino acids were present at desired levels . The growth studies with Methanosarchina mazei on emthanol and acetate indicated that the organism can rapidly utilize acetate and methanol for growth. The organism showed a high tolerance to acetate; quantitative yields of methane were obtained from upto 2 % acetate. The cellulase titres produced by C. biazotea from Kallar grass saccharificatied Kallar grass to some extent. The hydrolytsates were converted to methane precursors with Klebsiella sp for subsequent conversion of methane by M. mazei. The gass mixture had 60 % methane and 35% Co2. NaOH treatment gave increased cellulose degradation with concomitant increase in methane production. Maximum concentration of Kallar grass for higher methane production was established alongwith the concentration of exogenous supplements. These studies indicated that upto 10 % carbohydrates of Kallar grass remain unconverted in the digestor. The celluloytic complex including I²-glucosidease of such organisms needs improvement in order to more effectively gair monomeric sugars.

Effect of metal salts and protein modifying agents on activity of thermostable alpha-amylase produced by Bacillus licheniformis M27 under solid state fermentation

Abstract: The data on the effect of metal salts and protein modifying agents on the enzyme produced by B. licheniformis under solide state fermentation (SSF) process are reported and compared with those of the enzymes from other B. licheniformis and Bacillus strains. The bacterial α-amylase produced under SSF technique was not purified or characterized earlier

Studies on the Production of Microbial Rennet by Solid State Fermentation

Abstract: Due to acute shortage of calf rennet in recent years fungal rennets have received wide acceptability as calf rennet substitutes. A potent strain of Mucor miehei, a thermophilic fungus, was cultivated under Solid State fermentation conditions for the first time. The effect of some important nutritional parameters on the first time. the effect of some important nutritional parameters on the production of milk clotting activity was investigated. Milk clotting enzyme also known as acid protease is obtained from fungi and is similar to either pepsin or chymosin. Chymosin is the main milk clotting component of the calf rennet or rennet extract. It is known that the action of chymosin on kappa casein of milk is primarily responsible for the formation of cheese coagulation (Anstrup 1980). Studies were conducted in submerged fermentation conditions and found that rennet production on solid state fermentation was cheaper than produced in submerged fermentation. The proteolytic activity of rennet produced in submerged fermentation and solid state fermentation was also compared, and reported that rennet produced on solid state fermentation was having less proteolytic activity than the submerged grown culture. The effect of some important nutritional parameters on the production of milk clotting activity was investigated. Six complex type carbon sources were tried and wheat flour at 90:10 ratio gave a milk clotting activity of 34000 SU/g of dry moldy bran. Among the inorganicand organic nitrogen sources tried, organic sources favored higher enzyme production. The maximum milk clotting enzyme activity obtained was 58,000 su/g. The euzyme had a high ratio of milk clotting to proteolytic activity comparable to the commercial fungal rennets in the market. The cheese prepared from the enzyme was favorably evaluated in organoleptic tests.

Characterization of the solid-state fermentation of cassava.

Abstract: The solid-state fermentation of cassava (Mannlhot esculenta Crantz) was characterized by determining pH and biological oxygen demand (BOD). The results showed a strong association (ϱ=0.73) between pH of the fermenting slurry and that of the waste llquor. BOD of the liquor decreased as fermentation progressed. After 96 h fermentation, BOD was about 6×102 mg/l. Progress of cassava fermentation can probably be determined indirectly by following the changes in the pH and BOD profiles of the liquor.