ABSTRACT:The cellulolytic enzyme-endoglucanase activity against coir fibre, a major biowaste by bacteria such as Cellulomonas, Bacillus and Micrococcus spp. isolated from coir retting effluents of estuarine environment was studied. The enzyme assay was carried out by using various concentrations (0.5 -2%) of substrate of coir powder as a carbohydrate in different pH (5 -9) and temperature (20 -50 °C). The enzyme activity was minimum in 0.5% substrate concentration at lower pH 5 (0.0087, 0.0143 and 0.0071 U/mL) and at 20 °C temperature (0.0151, 0.0154 and 0.0122 U/mL) by the bacterial strains such as Cellulomonas, Bacillus and Micrococcus spp respectively. Then this level was increased and reached maximum at the neutral pH (0.0172, 0.0165 and 0.0121 U/mL) and at 40 °C (0.0336, 0.0196 and 0.0152 U/mL) by the selected bacterial species. Further increase of pH and temperature, the enzyme activity reduced considerably to 0.0083, 0.0143 and 0.0037 U/mL at pH 9 and 0.0154, 0.0197 and 0.0121 U/mL at 50 °C by the tested bacterial strains.The same trend was also obtained in oth er substrate concentrations such as 1.0, 1.5 and 2.0 %. With in the four substrate concentrations, the endoglucanase enzyme activity was more in 1.5% concentration at the tested pH and temperatures. From the over all result, it was observed that, among the three bacterial strains, the enzyme activity was more in Cellulomonas sp, followed by Bacillus and Micrococcus spp. in varying pH and temperature.

The Lactobacillus plantarum strain was isolated from grass silage that produces a broad spectrum of antifungal compound, active against food and feed-borne filamentous fungi in agar plate assay. Aspergillus fumigatus and Rhizopus stolonifer were the most sensitive among molds. No inhibitory activity could be detected against mold Penicillium roqueforti. Enhanced antifungal activity was observed at 30°C in pH 6.5. Minimum inhibitory concentration values against fungal cultures were ranged from 6.5 to 12.0 mg/ml for commercial 3-phenyllactic acid. The production of antifungal compound phenyllactic acid (PLA), lactic acid, and acetic acid by L. plantarum strain was also investigated. Structure characterization of the antifungal compound was carried out by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and gas chromatography. The produced compound (PLA) acted as a fungistatic and delayed the growth of a variety of fungal contaminants.

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The effects of supplementing diets with acetone extract (1% w/w) from four medicinal plants (Bermuda grass Cynodon dactylon, H(1), beal Aegle marmelos, H(2), winter cherry Withania somnifera, H(3) and ginger Zingiber officinale, H(4)) on growth, the non-specific immune response and ability to resist pathogen infection in tilapia Oreochromis mossambicus were assessed. In addition, the antimicrobial properties of the extract were assessed against Vibrio alginolyticus, Vibrioparahaemolyticus, Vibrio mimicus, Vibrio campbelli, Vibrio vulnificus, Vibrio harveyi and Photobacterium damselae. Oreochromis mossambicus were fed 5% of their body mass per day for 45 days, and those fed the experimental diets showed a greater increase in mass (111-139%) over the 45 days compared to those that received the control diet (98%). The specific growth rate of O. mossambicus fed the four diets was also significantly greater (1.66-1.93%) than control (1.52%) diet-fed fish. The blood plasma chemistry analysis revealed that protein, albumin, globulin, cholesterol, glucose and triglyceride levels of experimental fish were significantly higher than that of control fish. Packed cell volume of the blood samples of experimental diet-fed fish was also significantly higher (34.16-37.95%) than control fish (33.0%). Leucocrit value, phagocytic index and lysozyme activity were enhanced in fish fed the plant extract-supplemented diets. The acetone extract of the plants inhibited growth of Vibrio spp. and P. damselae with extracts from W. somnifera showing maximum growth inhibition. A challenge test with V. vulnificus showed 100% mortality in O. mossambicus fed the control diet by day 15, whereas the fish fed the experimental diets registered only 63-80% mortality at the end of challenge experiment (30 days). The cumulative mortality index for the control group was 12,000, which was equated to 1.0% mortality, and accordingly, the lowest mortality of 0.35% was registered in H(4)-diet-fed group.

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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.

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.

Extracellular protease production by Bacillus cereus isolated from the intestine of fish Mugil cephalus has been investigated in shake-flask experiment using different preparations of tuna-processing waste such as raw fish meat, defatted fish meat, alkali hydrolysate, and acid hydrolysate as nitrogen source. Among the tuna preparations tested, defatted fish meat supported the maximum protease production (134.57±0.47 U ml −1 ), and 3% concentration of the same was found to be optimum for maximizing the protease production (178.50±0.28 U ml −1 ). Effect of carbon sources on protease production in the optimized concentration of defatted tuna fish meat revealed that galactose aided the higher protease production (259.83± 0.04 U ml -1 ) than the other tested carbon sources and a concentration of 1.5% galactose registered as optimum to enhance the protease production (289.40±0.16 U ml −1 ). The halotolerancy of B. cereus for protease production indicated that 3% of sodium chloride was optimum to yield maximum protease (301.63±0.20 U ml −1 ). Among the surfactants tested, protease production was high in Triton X 100-added medium (298.63±0.12 U ml −1 ) when compared to other surfactants, and its optimum concentration recorded was 0.8% (320.57 ± 0.17 U ml −1 ) for more protease production. Partial characterization of crude enzyme revealed that pH 7.0 (278.90±0.08 U ml −1 ) and 60°C temperature (332.37±0.18 U ml −1 ) were optimum for better protease activity by B. cereus.