There is a growing interest to find alternate bioresources for production of ethanol, apart from cane/sugar beet molasses and starchy crops like sweet sorghum, cassava and sweet potato. Mahula (Madhuca latifolia L.) is a forest tree abundantly available in the Indian subcontinent and its flowers are very rich in fermentable sugars (28.1-36.3 g 100 g(-1)). Batch fermentation of fresh and 12-month-stored flowers with free (whole cells) and immobilized cells of Saccharomyces cerevisiae (strain CTCRI) was carried out in 2-l Erlenmeyer flasks. The ethanol yields were 193 and 148 g kg(-1) (using free cells) and 205 and 152 g kg(-1) (using immobilized cells) from fresh and 12-month-stored mahula flowers, respectively.
The purpose of this investigation was to study the effect of Streptomyces erumpens cells immobilized in various matrices, i.e., agar-agar, polyacrylamide, and luffa (Luffa cylindrica L.) sponge for production of alpha-amylase. Luffa sponge was found to be 21% and 51% more effective in enzyme yield than agar-agar and polyacrylamide, respectively. Response surface methodology was used to evaluate the effect of three main variables, i.e., incubation period, pH, and temperature on enzyme production with immobilized luffa cells. The experimental results showed that the optimum incubation period, pH, and temperature were 36h, 6.0, and 50 degrees C, respectively. The repeated batch fermentation of immobilized cells in shake flasks showed that S. erumpens cells were more or less equally physiologically active on the support even after three cycles of fermentation (3,830-3,575 units). The application of S. erumpens crude enzyme in liquefying cassava starch was studied. The maximum hydrolysis of cassava starch (85%) was obtained with the application of 4ml (15,200 units) of crude enzyme after 5 h of incubation.
Alpha amylases have various applications in food processing industries, for example, baking, brewing and distillery industries. Studies of the Ca 2+ independent α-amylase production were carried out by a strain of Bacillus brevis MTCC 7521 isolated from a brick kiln soil. The optimum temperature, pH and incubation period for amylase production were 50°C, 6.0 and 36 h, respectively. The enzyme secretion was at par in the presence of any of the carbon sources (soluble starch, cassava starch and cassava flour). B. brevis produced more amylase in presence of beef extract as nitrogen source in comparison to other organic nitrogen sources (peptone, yeast extract and casein) and asparagine, potassium nitrate, ammonium sulphate, ammonium nitrate and urea reduced the enzyme activity. The addition of Ca 2+ (10-40 mM) or surfactants (Tween 20, Tween 40, Tween 60, Tween 80, and sodium lauryl sulphate at 0.02% concentration) in culture medium did not result in further improvement in the enzyme production. The purified enzyme had a molecular mass of 205 kDa in native SDS-PAGE.
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