Isolation And Identification Of Tea Saponin-degradation Strains And Optimization Of Its Degradation Conditions And Application In Fermented Tea Seed Cake Feed

Three bacterial strains were isolated from the oil mill soils contaminated with tea cake by using Tea Saponin as the sole source of carbon and resistance test to chloramphenicol. According to their morphological observation, physiological biochemical characteristics, and the result of sequences alignment of16S rDNA, the strains were identified and named as Citrobacter sp. FCTS301, Pantoea sp. FCTS302and Enterobacter sp. FCTS303respectively.The fermentation conditions of the strains were studied by the single-factor and response surface analysis methodology. The single-factor results showed that:the optimum culture conditions of Citrobacter sp. FCTS301are cultivated with inoculation size of6%at33℃, pH7.0under agitation (150rpm) containing10.0g/L tea saponin; the optimum culture conditions of Pantoea sp. FCTS302are cultivated with inoculation size of8%at33℃, pH7.0under agitation (150rpm) containing5.0g/L tea saponin; the optimum culture conditions of Enterobacter sp. FCTS303are cultivated with inoculation size of8%at33℃, pH7.0under agitation (150rpm) containing10.0g/L tea saponin. From the single-factor results,we can conclude that Citrobacter sp. FCTS301has the highest degradation rate of tea saponin. With Response Surface Analysis(RSA), the following optimum culture conditions are obtained:initial pH7.2, culture temperature34.2℃and inoculation size7.3%. Under these conditions, the actual optimum degradation rate of tea saponin was83.6%and the relative error with the predicted value is1.21%.The single-factor and response surface analysis methodology were used to optimize the extraction process parameters of tea saponin from tea seed cake (Camellia oleifera) in this paper. The optimum conditions of the single factor experiment were:extracted with70%ethanol and solvent-to-feed ratio of4at70℃for4h. The experiments were arranged according to Box-Behnken central composite experiment design. Based on single-factor experiments, three independent variables, ethanol concentration, extraction time and solvent-to-feed ratio, were selected as affecting factors during extraction. Response surface analysis method was applied to determine the effect of central composite experiment design. The optimum ultrasound extraction conditions were found to be extracted with72%ethanol and solvent-to-feed ratio of4.5at70℃for3.8h. The predicted extraction yield of tea saponin is14.54%, while the actual extraction yield of tea saponin is14.22%, with relative error of2.20%.The suitable inoculation proportion and strains combination for fermentation of tea seed cake were obtained by mixed strains combination experiment. According to test results, the optimum strains combination are Citrobacter sp. FCTS301, Aspergillus oryzae FCJX001, Saccharomyces cerevisiae FCJX501and Lactobacillus FCJX103, and their inoculation proportion are5%,0.5%,1.0%and1.5%respectively. Crude protein of tea seed cake increased by36.71%after cultivated at34℃,150rpm for10days, while crude fiber content and tea saponin decreased42.83%and54.45%respectively.