High-cell-density fed-batch culture of Saccharomyces cerevisiae KV-25 using molasses and corn steep liquor.
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High-cell-density cultivation of yeast was investigated using the agricultural waste products corn steep liquor (CSL) and molasses. The Saccharomyces cerevisiae KV-25 cell mass was significantly dependent on the ratio between C and N sources. The concentrations of molasses and CSL in the culture medium were statistically optimized at 10.25% (v/v) and 16.87% (v/v), respectively, by response surface methodology (RSM). Batch culture in a 5-l stirred tank reactor using the optimized medium resulted in a cell mass production of 36.5 g/l. In the fed-batch culture, the feed phase was preceded by a batch phase using the optimized medium, and a very high dried-cell-mass yield of 187.63 g/l was successfully attained by feeding a mixture of 20% (v/v) molasses and 80% (v/v) CSL at a rate of 22 ml/h. In this system, the production of cell mass depended mainly on the agitation speed, the composition of the feed medium, and the glucose level in the medium, but only slightly on the aeration rate. (+info)
Conversion of shrimp shell by using Serratia sp. TKU017 fermentation for the production of enzymes and antioxidants.
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A chitinase (CHT), and a protease (PRO) were purified from the culture supernatant of Serratia sp. TKU017 with shrimp shell as the sole carbon/nitrogen source. The molecular masses of CHT and PRO determined by SDS-PAGE were approximately 65 kDa and 53 kDa, respectively. CHT was inhibited by Mn2+, Cu2+ and PRO was inhibited by most tested divalent metals, EDTA. The optimum pH, optimum temperature, pH stability, and thermal stability of CHT and PRO were (pH 5, 50 degrees , pH 5 degrees ) and (pH 9, 40 degrees , pH 5 degrees ), respectively. PRO retained 95% of its protease activity in the presence of 0.5 mM SDS. The result demonstrates that PRO is SDS-resistant protease and probably has a rigid structure. The 4th day supernatant showed the strongest antioxidant activity (70%, DPPH scavenging ability) and the highest total phenolic content (196+/-6.2 microng of gallic acid equival/mL). Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and free amino groups, were found for the supernatant. With this method, we have shown that shrimp shell wastes can be utilized and it's effective in the production of enzymes and antioxidants, facilitating its potential use in industrial applications and functional foods. (+info)
Application of molecular techniques to elucidate the influence of cellulosic waste on the bacterial community structure at a simulated low-level-radioactive-waste site.
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A recycling index for food and health security: urban Taipei.
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The modern food system has evolved into one with highly inefficient activities, producing waste at each step of the food pathway from growing to consumption and disposal. The present challenge is to improve recyclability in the food system as a fundamental need for food and health security. This paper develops a methodological approach for a Food Recycling Index (FRI) as a tool to assess recyclability in the food system, to identify opportunities to reduce waste production and environmental contamination, and to provide a self-assessment tool for participants in the food system. The urban Taipei framework was used to evaluate resource and nutrient flow within the food consumption and waste management processes of the food system. A stepwise approach for a FRI is described: (1) identification of the major inputs and outputs in the food chain; (2) classification of inputs and outputs into modules (energy, water, nutrients, and contaminants); (3) assignment of semi-quantitative scores for each module and food system process using a matrix; (4) assessment for recycling status and recyclability potential; (5) conversion of scores into sub-indices; (6) derivation of an aggregate FRI. A FRI of 1.24 was obtained on the basis of data for kitchen waste management in Taipei, a score which encompasses absolute and relative values for a comprehensive interpretation. It is apparent that a FRI could evolve into a broader ecosystem concept with health relevance. Community end-users and policy planners can adopt this approach to improve food and health security. (+info)
Non-rural point source blastomycosis outbreak near a yard waste collection site.
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