Hyperproduction of γ-glutamyl transpeptidase from Bacillus licheniformis ER15 in the presence of high salt concentration

Background: Microbial γ-glutamyl transpeptidases (GGTs) have been exploited in biotechnological, pharmaceutical, and food sectors for the synthesis of various γ-glutamyl compounds. But, till date, no bacterial GGTs are commercially available in the market because of lower levels of production from various sources. In the current study, production of GGT from Bacillus licheniformis ER15 was investigated to achieve high GGT titers. Results: Hyperproduction of GGT from B. licheniformis ER15 was achieved with 6.4-fold enhancement (7921.2?±?198.7?U/L) by optimization of culture medium following one-variable-at-a-time strategy and statistical approaches. Medium consisting of Na₂HPO₄: 0.32% (w/v); KH₂PO₄: 0.15% (w/v); starch: 0.1% (w/v); soybean meal: 0.5% (w/v); NaCl: 4.0% (w/v), and MgCl₂: 5?mM was found to be optimal for maximum GGT titers. Maximum GGT titers were obtained, in the optimized medium at 37°C and 200?rpm, after 40?h. It was noteworthy that GGT production was a linear function of sodium chloride concentration, as observed during response surface methodology. While investigating the role of NaCl on GGT production, it was found that NaCl drastically decreased subtilisin concentration and indirectly increasing GGT recovery. Conclusion: B. licheniformis ER15 is proved to be a potential candidate for large-scale production of GGT enzyme and its commercialization.     

Antifeeding and insect-growth-regulating activity of certain metal complexes towardsSpodoptera litura; F

Metal complexes of divalent cobalt, nickel and copper and trivalent iron were synthesized usingN-salicylidene-3-aminocoumarin as chelating agent. The ligand behaves as a monobasic ONO donor towards Co(II), Ni(II) and Cu(II) and as an ON as well as an ONO donor towards Fe(III). All the complexes haven been proposed to have octahedral geometry on the basis of analytical, thermal conductivity, spectral and magnetic data. The complexes have been screened againstSpodoptera litura;F (Lepidoptera: noctuiidae) for antifeeding and insect-growth-regulating activity. The results show appreciable insect-growth-regulating activity associated with metal complexation.