SUBSTRATE CARRIERS FOR C-1(2)-DEHYDROGENATION OF 6-METHYLENE ANDROSTENEDIONE TO EXEMESTANE BY GROWING AND IMMOBILIZED ARTHROBACTER SIMPLEX NCIM 2449

Objective: Permeability of hydrophobic steroid substrates across cell membrane is a critical factor during microbial bioconversion. To increase substrate intake, the feasibility of some organic solvents and emulsifiers as substrate carrier on the bioconversion of 6-methylene androstenedione to exemestane was assessed.Methods: Androstenedione, a commonly available steroid precursor, was chemically converted 6-methylene androstenedione. The time course of exemestane accumulation was estimated after addition of 6-methylene androstenedione dissolved in some organic solvents or dispersed with emulsifiers by growing and immobilized cells of Arthrobacter simplex NCIM 2449 in shake flask cultures.  Results: The use of substrate carriers for addition of 6-methylene androstenedione enhanced the bioconversion several folds. With growing bacterium in triplicate flasks, a peak mol % bioconversion recorded was- ethanol (67.25, 72 h); soybean oil + tween 80 (50.37, 48 h); acetone (38.84, 48 h); soybean oil (38.36, 48 h); lecithin (32.73, 48 h), methanol (32.71, 48 h) and tween 80 (10.37, 48 h). As compared to the growing cells, the bioconversion with Ca-alginate immobilized cells was delayed and peak mol % bioconversion was recorded as ethanol (60.78, 120 h); soybean oil + tween 80 (42.98, 120 h);  methanol (40.50,  72 h);  soybean oil (38.36, 48 h);  acetone (31.18, 72h ) and lecithin (33.67, 120 h); tween 80 (13.87, 120 h).Conclusion: The use of substrate carriers for addition of 6-methylene androstenedione increased the permeability of substrate and may be used to increase the yield of exemestane and reduce incubation time

QUANTIFICATION OF EXEMESTANE ACCUMULATION DURING MICROBIAL BIOCONVERSION BY TLC IMAGE ANALYSIS

Objective: The present study was aimed at developing a rapid, cost effective and accurate method for quantification of exemestane using thin layer chromatography (TLC) separation followed by image analysis and to test it for monitoring the accumulation of exemestane during microbial bioconversion.Methods: After microbial bioconversion and TLC separation of products formed, exemestane was quantified using ImageQuant TL v2003 image analysis software and the results were compared with high performance liquid chromatography (HPLC) analysis.Results: The percentage error between TLC and HPLC analyses was ranged from (-) 5.18 to (+) 5.51. Bacterial strains Arthrobacter simplex IAM 1660, Nocardia sp. MTCC 1534, Pseudomonas putida MTCC 1194 and Rhodococcus rhodochorus MTCC 291 respectively yielded 79.7 (72 h), 63.9 (72 h), 69.8 (96 h) and 83.2 (96 h) mole percent bioconversion of 6-methylene androstenedione to exemestane. Conclusion: Rhodococcus rhodochorus MTCC 291 was found to be the most suitable organism for the bioconversion and may be used to develop an eco-friendly route to replace chemical synthesis that eliminates the use of toxic chemicals and side products

AVERMECTIN PRODUCTION BY SOLID STATE FERMENTATION-A NOVEL APPROACH

Objective: The present study was carried out to evaluate SSF process for the production of avermectin by Streptomyces avermitilis NRRL 8165 using easily available grains, millets and some agricultural by-product.Methods: Various substrates were screened for their ability to support avermectin production. Different parameters to maximize the yield of avermectin by S. avermitilis NRRL 8165 under SSF were optimized by conventional one factor at a time approach and parameters optimized earlier were adopted for the subsequent study.Results: Sorghum seeds used as solid substrate supported maximum growth and total avermectin production (4.6 mg g-1 dry substrate). The optimum values for maximum avermectin production were: moistening medium containing g l-1 KH2PO4 1; MgSO4.7H2O 0.4, inoculum size 20 % (24 h old culture in yeast extract-malt extract dextrose medium) v/w of initial dry substrate, substrate particle size 0.5 to 4 mm, incubation temperature 28 °C, initial moisture level 105%, incubation period of 15 d, 8 % w/w sucrose and 5% w/w soyameal. The avermectin yield with optimized fermentation condition was 5.8 mg g-1 dry substrate which is 1.3 fold higher as compared to non-optimized condition.Conclusion: Avermectin produced by S. avermitilis are widely used as an anthelmintic agent in the medical, veterinary and agricultural applications. In comparison with submerged fermentation, SSF can become an alternative cost-effective method for the production of avermectin. This report demonstrates the feasibility of employing agro-based substrate, that could reduce antibiotics production cost

Bioconversion of 16-dehydropregnenolone Acetate to Exclusively 4-androstene-3,17-dione by Delftia acidovorans MTCC 3363

Delftia acidovorans MTCC 3363 was found to convert 16-dehydropregnenolone acetate (16-DPA) exclusively to 4-androstene-3, 17-dione (AD). Addition of 9α-hydroxylase inhibitors was not required for preventing the accumulation of byproducts. The effect of pH, tempera­ture, substrate concentration, surfactants and carrier solvents on this bioconversion has been studied. 16-DPA was maximally converted in buffered medium at pH 7.0, at temperature 30°C and 0.5 mg ml–1 substrate concentration. Detergent addition and temperature above 35°C had deleterious effect on bioconversion. Dioxan was found to be the best carrier solvent for biotransformation of 16-DPA to AD

Gallotannin hydrolysis by immobilized fungal mycelia in a packed bed bioreactor

94-97Hydrolysis of gallotannin to gallic acid by immobilized mycelia of Aspergillus niger MTCC 282, Aspergillus fischerii MTCC 150, Fusarium solani MTCC 350 and Trichoderma viride MTCC 167 in a packed bed bioreactor was studied. Fungal mycelia pre induced with 5 g L-1 gallotannin were immobilized in calcium alginate gel (1.5%) and the resultant beads were packed in a column to a bed volume of 175 mm3. Gallotannin dissolved in distilled water was passed through the column and the eluate was recycled after adjusting pH to 6 with ammonium hydroxide (10%). Maximwn hydrolysis of gallotannin was recorded by immobilized mycelia of F. solani and T. viride at 35° and 45°C after 175 and 60 min of residency period respectively. Optimum substrate concentration required for maximum hydrolysis was 10g L-1 at pH 5 for both the fungi. Immobilized mycelia of A. niger and A. fischerii revealed maximum operational stability. Loss of activity after eighth run was in the order of - A. niger (no loss), A. fischerii (7.5%), F. solani (18%) and T viride (18%). Stability in terms of retention of enzyme activity after 150 days of storage at 4°C was A. niger (58%), A. fischerii (26.8%), F. solani (83%) and T viride (85 .1 %). </span

Revisted Blocksom vesicostomy: Operative steps

Posterior urethral valves (PUVs) are the most common cause of infravesical outflow obstruction in boys. Vesicostomy is considered in selective cases of PUV as an initial temporary procedure. The most commonly followed procedure is the one described by Blocksom. The procedure is simple and easy to perform. We revisited this procedure and describe the operative steps