Production of antimicrobial peptides has gained lot of significance in the present day research. Most of the recombinant proteins are generally produced from IPTG inducible E. coli BL21(DE3). As an alternative, considering the factors like cost and toxic nature of IPTG, salt inducible Escherichia coli GJ1158 was used in the present study for the production of synthetic cationic antimicrobial peptide by fed batch fermentation. This study was conducted to optimize the physico-chemical parameters viz., dissolved oxygen concentration (DOC) and nutritional factors viz., carbon, nitrogen and phosphate sources on bacterial growth and peptide production. Even after increase in DOC more than 30 % in batch culture has no effect on expression, but significant improvement in fed-batch cultivation was observed beyond 30% DOC. Supplementation of production medium with different pulses of nutrient sources like dextrose mono hydrate, yeast extract and Na 2 HPO 4 enhanced the expression in fed batch fermentation process even without disturbing the cell growth at 40 % DOC. When growth reached 15 g/L of dry cell weight, culture was induced with 150 mM NaCl and further cultured for next 15 hr (16.37 g/L dry cell weight). Approximately, 258 mg/L of pure peptide was obtained by using modified GYEON medium. The peptide thus produced is tested for its antimicrobial activity, devoid of hemolytic activity. The fed-batch fermentation which emphasizes, this was the highest reported concentration of recombinant synthetic peptide from salt inducible expression host till to date, which manages to gratify the present day industrial production of the peptides cost-effectively.

Engineered synthetic cationic antimicrobial peptides are the potential alternative drugs to existing antibiotics. In the present study, a novel attempt for the intracellular production of engineered synthetic cationic antimicrobial peptide (escAMP) using Pichia pastoris was studied. The engineered synthetic cationic antimicrobial peptide gene was synthesized using overlapping PCR. An entirokinase and hydroxylamine hydrochloride cleavage sites are incorporated at N-and C-terminal end of escAMP respectively for easy purification. Later the gene was inserted into the MCS region of pPICZ-B vector. The synthetic peptide under the AOX1 promoter was integrated into the Pichia pastoris GS115 genome and the recombinant clones were screened by using antibiotic resistance. Expression profiles of recombinant peptide were done using glycerol and methanol based synthetic medium and analysed on 18 % Tricine-SDS-PAGE. Purification of the expressed peptide was done after cell disruption (10 cycles on time, 10 cycles off time and 10 min of total time) using 6X histidine tag followed by enzymatic cleavage. In this study, 67 gm of dry cell weight/L and 580 mg/L of purified escAMP was produced. The purified peptide is analysed for its anti microbial activity against different Gram positive and Gram negative microbes. For the first time smallest engineered synthetic cationic peptide was designed, cloned and expressed from methanol inducible Pichia pastoris GS115 and production ranges are encouraging.

In recent years there has been a phenomenal increase in the use of alkaline proteases as industrial catalysts. These enzymes offer advantages over the use of conventional chemical catalysts for numerous reasons, for example they exhibit high catalytic activity, a high degree of substrate specificity, can be produced in large amounts and are economically viable. Bacterial alkaline proteases constitute an important group of industrial enzymes. The objective of the present study was to determine the significant parameters in the economical production and optimize the conditions for alkaline protease by Bacillus subtilis MTCC1790 in submerged fermentation by using Taguchi experimental design. This approach facilitated the study of interaction of a large number of variables spanned by factors and their settings with a small number of experimental runs leading to considerable economy in time and cost for the process optimization. There are Five factors viz., carbon, nitrogen, metal ions, inoculum% and agitation, each at two levels were selected and an orthogonal array layout of L16 (4)5 performed. The experiment result indicated that dextrose (0.6%), NH 4 Cl (0.6 %), Ca 2+ as metal ions, inoculum (8%) and agitation (100 rpm) were the important factors for alkaline protease production. At this optimum condition, the yield of protease production by Bacillus subtilis MTCC1790 was found to be 286 U/mL.