Optimization of Inexpensive Agricultural By-Products as Raw Materials for Bacitracin Production in Bacillus licheniformis DW2

Bacitracin is a broad-spectrum antibiotic used extensively as a feed additive. In this study, inexpensive agricultural by-products were used as nitrogen sources for bacitracin production. Based on both the orthogonal tests, a combination of 7% soybean meal (SBM) +2% low protein rapeseed cake (LPRC) was optimal for bacitracin production. Compared to the original formula, the titer of bacitracin increased by 20.5% reaching 910.4 U/ml in flasks. The titer of bacitracin and the ratio of bacitracin A increased by 12.4 and 6.8% in a 50-l fermentor. Furthermore, this study also explored the effects of exogenously adding different amino acids on the yield of bacitracin. The addition of Cys and Glu enhanced bacitracin production by 5.7 and 5.0%, respectively. This study provided the inexpensive nutrient inputs into efficient bacitracin production and also the insight to further research enabling better utilization of oil cakes for economic viability of the bioprocess industry.

Oil cakes and their biotechnological applications--a review

Oil cakes have been in use for feed applications to poultry, fish and swine industry. Being rich in protein, some of these have also been considered ideal for food supplementation. However, with increasing emphasis on cost reduction of industrial processes and value addition to agro-industrial residues, oil cakes could be ideal source of proteinaceous nutrients and as support matrix for various biotechnological processes. Several oil cakes, in particular edible oil cakes offer potential benefits when utilized as substrate for bioprocesses. These have been utilized for fermentative production of enzymes, antibiotics, mushrooms, etc. Biotechnological applications of oil cakes also include their usages for vitamins and antioxidants production. This review discusses various applications of oil cakes in fermentation and biotechnological processes, their value addition by implementation in feed and energy source (for the production of biogas, bio-oil) as well.

Isolation of a chitinase overproducing mutant of Streptomyces peucetius defective in daunorubicin biosynthesis

Streptomyces peucetius, producer of the antitumor anthracycline antibiotic daunorubicin, was mutagenized, and mutants defective in daunorubicin biosynthesis were screened. One mutant (SPVI), which failed to produce daunorubicin, was found to overproduce an extracellular chitinase. Time course analyses of chitinase production and of the extracellular protein profile showed that the increase in activity is due to increased synthesis of the enzyme protein. The production of chitinase in SPVI was repressed by glucose as in the case of wild-type S. peucetius. PFGE analysis of VspI restriction fragments of S. peucetius and SPVI showed that there was no major alteration in the mutant genome. The hybridization pattern of S. peucetius and SPVI genomic DNA digested with various restriction enzymes was identical when probed with dnrUVJI genes of the S. peucetius daunorubicin cluster and chiA of Streptomyces lividans 66. The possible step affected in the daunorubicin biosynthetic pathway could be a polyketide synthase, since aklanonic acid, the earliest detectable intermediate in the daunorubicin pathway, was not synthesized in SPVI.Key words: Streptomyces peucetius, chitinase, daunorubicin, NTG mutagenesis.