Studies On Screening Of Probiotic Lactobacillus Spp And Fermentation Engineering On Apple Pomace

Objectives: (1) to establish a new model of screening of probiotic Lactobacillus spp to serve as the major strain to ferment apple pomace (AP); (2) to set up a technology of acidity decreasing by fermentation with Schizosaccharomyces pombe to ascend pH value; (3) to ferment AP with probiotic Lactobacillus spp screened in order to make bio-feed from AP have inhibitory activity against microbe.The main results and conclusions:A new screening model, which process is pre-screening, isolation, and then screening, was established and used to screen probiotic Lactobacillus spp. From 5 samples of pig feces, 18 strains with high inhibitory activity against E coli were isolated, among them 15 strains could exclude three E coli pathogen related such as K88, K99, 987P from culture media. The efficiency of screening improves significantly compared with conventional models. Biological characteristics involved of screened Lactobacillus spp were studied. One strain of yeast, numbered M1, which could improve the reproduction of Lactobacillus spp is screened at the same time.Biodegradation of organic acid method is used to ascend pH value so as to make AP suit to Lactobacillus spp fermentation. A strain of Schizosaccharomyces pombe CICC 1757 is selected for its L-malate degradation, which could reduce L-malate by 96.26% , and total acidity by 60% in AP, ascend pH value from 4.0 to maximal 5.0. The technology of biodegradation was studied, the optimum parameters were obtained as: addition of H2SO3, 100mg/kg; seed volume, 10%; temperature, 28 C; batch fermentation period, 24hours,without stirring.After adjustment of pH value of AP fermented by Schizosaccharomyces pombe CICC 1757, A stain of Lactobacillus sp, and A strain of yeast screened, numbered T29 and MI respectively were used to ferment AP, as a result, fermented product with high inhibitory activity against E coli was got. The product contains lactic acid by 1.69%, but not malate and acetate; the substances inhibitory activity against E coli pathogen related, are bacteriocin-like, thermo-tolerant, influenced by its biomass and period of stable phase. Biomass of Lactobacillus sp in fermented product is 2.2 X 108CFU/g.After fermentation, the total flavonoids survive by 92.76%, free flavonoids ascend by 20% compared with AP.The product contains some elements of antibiotics substitute as lactate, free flavonoids, bacteriocin-like and probiotic Lactobacillus spp; The possible mechanism of improving the functinal activity of AP is: probiotic Lactobacillus spp ferments and produces lactate, bacteriocin-like, and -glucosidase which transforms cojugated flavonoids into free ones.Significance and impact of the study: Through establishing the model, screening efficiency of probiotic Lactobacillus spp is improved; through creating a new way to utilize AP, Environmental issue resulted from AP will be improved; The biofeed from AP contains some elements of antibiotics substitute, will promise to improve the value of AP when use as feed; the solid state fermentation of AP meets the need of modern aims of sustainable development, green environment.