Biotransformation of cholesterol using Lactobacillus bulgaricus in a glucose-controlled bioreactor.

A novel single-step microbial transformation process for the production of testosterone from cholestrol by Lactobacillus bulgaricus in an aerated fermenter was investigated. The metabolism of glucose possibly supplying reducing power as NADH was necessary for the reduction of androst-4-en-3,17-dione (AD) to testosterone (TS). The growth period for the accumulation of testosterone in maximal amount and the residual glucose increased in parallel with the amount of glucose supplement in growth cultures. After the glucose in the fermentation culture was completely exhausted, most of the testosterone was oxidized to AD. Addition of a larger amount of glucose could prevent oxidation of testosterone to AD. The biotransformation of cholestrol was significantly increased in the presence of cyclodextrin (CD) in the fermenting medium. The addition of 0.1% CD to the growth medium facilitated the transport of the steroid substrate through the microbial cell wall.

Simultaneous raw starch hydrolysis and ethanol fermentation by glucoamylase from Rhizoctonia solani and Saccharomyces cerevisiae.

Crude glucoamylase preparation from Rhizoctonia solani was used to saccharify raw and cooked starch. Various concentrations of potato starch and wheat flour from 10-40%, w/v were used for mashing but 30% was found to be the optimal and economical. The saccharified mash yielded 5.89%, v/v ethanol in a simultaneous saccharification and fermentation process using a yeast strain Saccharomyces cerevisiae (SC-39) at 35 degrees C for 4 days. Removal of inhibitory substances from the fermenting broth through dialysis caused considerable increase in ethanol production.

Transformation of Progesterone by Traemetes hispida.

TRAEMETES HISPIDA was found to convert progesterone into a mixture of various products. Five products were isolated in sufficient amounts by HPLC analysis for structural identification and characterization. Three products were found to have two hydroxy moieties on axial and equatorial positions at 7beta,15beta, 6beta, 11alpha, and 11alpha, 15beta sites. The other two products had an extra 17alpha-hydroxy on the above dihydroxy derivatives to give trihydroxyprogesterone. The hydroxylating steps caused by this strain were greatly influenced by the 17beta side chain, especially by the C-20 moiety in the steroidal skeleton.

Sucrose: a constitutive elicitor of phytoalexin synthesis.

Extracts of seeds and leaves of the tropical legume Cajanus cajan (L.) Millsp. (the pigeon pea) elicited the accumulation of three phytoalexins when applied as droplets to superficially wounded leaves of the plant. The active component was purified and identified as sucrose. Phytoalexin accumulation was proportional to the logarithm of the concentration of sucrose applied, with maxima ranging from 338 to 455 micrograms per gram (fresh weight) of leaf tissue. The sucrose concentrations required to elicit half these amounts ranged from 20 to 35 micrograms per milliliter, but other sugars had little effect even at 1000 micrograms per milliliter. The elicitor activity of sucrose was abolished by actinomycin D, puromycin, and cycloheximide at a concentration of 10 micrograms per milliliter or greater, suggesting that gene derepression is required for expression of the phytoalexin response.