Halophilic organic solvent tolerant proteolytic bacterium was isolated from the marine sediment of Rajakkamankalam estuary and identified as Bacillus sp. APCMST-RS7. The alkaline protease synthesized by Bacillus sp. APCMST-RS7 was purified by using ammonium sulphate precipitation, dialysis and DEAE-Sepharose Fast Flow column. The purified protease showed 6.60-fold purity, 26.02 U/mg specific activity with 24.30 % yield. The molecular weight of the purified alkaline protease was 32 kDa. This purified protease registered maximum activity at pH 8 and it was stable between pH 8-9 after 1.30 h of incubation. The optimum temperature registered was 50°C and it was stable between 30 and 40°C even after 1.30 h of incubation. This enzyme also showed maximum activity at 1.5 M NaCl concentration. The Km and V max values registered were, 0.0002 g/l and 1428.57 U/ml, respectively. Further, magnesium chloride, barium chloride and copper sulphate influenced this enzyme activity remarkably and it was also found to be enhanced by many of the tested surfactants and solvents. Here, the serine protease inhibitor totally inhibited the enzyme activity; hence it is of serine protease family. The candidate bacterium effectively deproteinized the shrimp shell waste with maximum protease activity. The shrimp shell hydrolysate also exhibited maximum antioxidant activity.

BackgroundAquaculture is one amongst the growing and major food producing sectors. Shrimp culture is one of the subsectors of aquaculture that attracts more attention because of the economic interest. However, the shrimp culture systems have been facing severe consequences and economical losses due to disease outbreaks. Risk of disease outbreak can be combated with the application of probiotics. For economically viable production of such probiotic products, the present study provides information on the optimization and partial purification of bacteriocin produced by a goat milk isolate Lactobacillus sp. MSU3IR against the shrimp bacterial pathogens.ResultsBacteriocin production was estimated as a measure of bactericidal activity (arbitrary Unit/ml) over the test strains. The optimum culture conditions and media components for maximum bacteriocin production by Lactobacillus sp. MSU3IR were: pH: 5.0, temperature: 30°C, carbon source: lactose; nitrogen source: ammonium acetate; NaCl: 3.0% and surfactant: Tween 80. MRS medium was found to extend better bacteriocin production than other tested media. Upon partial purification of bacteriocin, the SDS-PAGE analysis had manifested the presence of two peptide bands with the molecular weight of 39.26 and 6.38 kDa, respectively.ConclusionThe present results provide baseline trend for the statistical optimization, scale up process and efficient production of bacteriocin by the candidate bacterial strain Lactobacillus sp. MSU3IR which could be used to replace the usage of conventional chemotherapeutics in shrimp culture systems.

No abstract

No abstract

An extracellular lipase produced by marine fish intestinal isolate Halobacillus sp. AP-MSU 8 was purified and characterized. The lipase was purified to homogeneity using ammonium sulphate precipitation, DEAE-Sepharose anion exchange chromatography and Sephadex G-75 gel filtration chromatography. The overall purification protocols resulted in 25 % yield of lipase with 10.6-fold. The SDS-PAGE (12 %) analysis of purified lipase resulted in the molecular mass of the purified lipase as 25-kDa. The optimum pH and temperature required for maximum activity of purified lipase was 9.0 and 40°C respectively. Also, this lipase is halo tolerant and requires 2.5 M NaCl for maximum activity. The activity of the purified lipase was more in the presence of BaCl 2 and MgSO 4 , and in contrast the enzyme activity was totally inhibited in the presence of ZnSO 4 and ZnCl 2 . The surfactants such as polyethylene glycol and Tween 20 enhanced the lipase activity. Likewise 10 % concentration of organic solvents such as benzene and acetone stimulated the lipase activity, whereas at 20 % concentration all the tested solvents inhibited the lipase activity.