6 research outputs found

    Volumetric oxygen mass transfer coefficient and surface tension in simulated salt bioremediation media

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    Toluene can be removed from contaminated sites via bioremediation. However, aeration and mixing must be optimized to ensure effective volumetric oxygen mass transfer coefficient (kLa). Such response was determined in different salt solutions, specifically basal saline medium, low saline medium, Bushnell-Hass medium and a medium simulating seawater, which were tested either as such, or supplemented with toluene as a model pollutant, or with glucose or yeast extract as carbon and nitrogen sources, or with surfactin as a biosurfactant. kLa values obtained at different agitation intensities and aeration rates were compared with those in water and correlated with power number and superficial gas velocity. Surface tension decreased when surfactin was added to toluene-containing media due to toluene-surfactin micelle formation. SeawaterThe seawater-simulating medium exhibited the highest surface tension reduction

    Physiochemical parameters optimization for enhanced nisin production by Lactococcus lactis (MTCC 440)

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    The influence of various physiochemical parameters on the growth of Lactococcus lactis sub sp. lactis MTCC 440 was studied at shake flask level for 20 h. Media optimization (MRS broth) was studied to achieve enhanced growth of the organism and also nisin production. Bioassay of nisin was done with agar diffusion method using Streptococcus agalactae NCIM 2401 as indicator strain. MRS broth (6%, w/v) with 0.15μg/ml of nisin supplemented with 0.5% (v/v) skimmed milk was found to be the best for nisin production as well as for growth of L lactis. The production of nisin was strongly influenced by the presence of skimmed milk and nisin in MRS broth. The production of nisin was affected by the physical parameters and maximum nisin production was at 30(0)C while the optimal temperature for biomass production was 37(0)C
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