Krishnamurthi Tamilarasan

Optimization of medium components and operating conditions for the production of solvent-tolerant lipase by Bacillus sphaericus MTCC 7542

The production of lipase by Bacillus sphaericus MTCC 7542 growing on basal media with various carbon, nitrogen sources and environmental conditions was studied. Studies were undertaken to improve lipase production. Olive oil, Tween 80, rice bran oil, sunflower oil, soybean oil, palm oil and groundnut oil were tested as different lipid sources in this medium, with olive oil at 1% giving a lipolytic activity of 0.19 U/ml after 48 h, which was the highest yield obtained in this study. The effect of carbon source was studied by adding glucose, fructose, sucrose, lactose, starch and cellulose to a medium containing potassium nitrate and other minerals maintained as constant. The best yield of 0.20 U/ml after 48 h was obtained with the medium supplemented with 0.2% of glucose. The effect of nitrogen source was studied by adding peptone, yeast extract, tryptone, gelatin, casein, ammonium chloride, urea, ammonium sulphate, ammonium nitrate and ammonium acetate. The maximum yield of 0.21 U/ml after 48 h was obtained with the medium supplemented with yeast extract and ammonium chloride. Enzyme production was best at 7.5 pH, within a range tested from 6.5 to 8. The maximum enzyme was obtained at 35°C within a range tested from 25 to 40°C. These results are promising because this strain produces lipase in an inexpensive medium and we succeeded in increasing the lipolytic activity 3-fold over the initial values obtained with the non-optimized medium. Key words : Bacillus sphaericus MTCC 7542, basal media, olive oil, lipolytic activity, ammonium chloride,mineral salts.

Integration of Lignin Removal from Black Liquor and Biotransformation Process

Industrial discharge has tremendously increased inorganic pollutants in water bodies all over the world. Paper and pulp mill effluent is included in one of the most pollution-generating discharges containing complex chemical compounds such as lignin. For clean and healthy water resources, the recovery of lignin from wastewater from the paper and pulp industry is of high importance. On the other hand, these pollutants can be carcinogenic, due to the chlorine lignin and chlorine phenols that are formed along the process. The main focus of this study on precipitation of lignin from the black liquor (influent) is one stage followed by dewatering/washing to improve purity of lignin. Lignin valorization is an essential process for an advanced, sustainable, and economical biomass-based industry. However, converting lignin into value-added products remains a challenge due to its heterogeneity and irregular structure. Complex nature of lignin depolymerized by aromatic-catabolizing organisms to create “biological funnels” that receive heterogeneous aromatic substrates and convert them to a few products. Microbes such as bacteria and fungi are involved in the lignin degradation. Degradation of lignin through white-rot fungi may be helpful for the biotechnical applications like biopulping, biobleaching and pulp mill effluents treatment, and soil bioremediation. White-rot fungi specifically P. chrysosporium, also known as model fungus, and Coriolus versicolor are potential degradation against recalcitrant chromophoric material in bleach plant effluents. The abundance and renewability of lignin potentially converted to valuable bioproduct may eventually replace existing technology on manufacturing industries.