| Paenibacillus mucilaginosus is a class of silicate bacteria, which could fix nitrogen as well asdissolve phosphate and potassium. It has been widely used in agriculture and sewage treatmentin China. P. mucilaginosus can produce capsular polysaccharides during the metabolic process ina specific environment. In order to investigate the application potential of capsularpolysaccharides in feed industry, the culture conditions were optimized to produce capsularpolysaccharides of P. mucilaginosus, and its effects on poultry rearing were investigated in thisstudy.Firstly, the effects of the content of three mian ingredients （sucrose, K2HPO4and CaCO3） onpolysaccharides production were analysed using single factor experiment. The results indicatedthat the viscosity and polysaccharides production increased with the content of sucrose in therange of0.5%2.5%, and the highest polysaccharides production （9.61±0.04mg/ml） wasobtained with2.5%sucrose. Similarly, the optimal contents was0.05%0.15%for dipotassiumphosphate and0.20.45%for calcium carbonate. The highest polysaccharides production was5.25±0.04mg/ml with0.15%dipotassium phosphate and4.40±0.05mg/ml with0.45%calciumcarbonate. The best culture time and temperature were72h and32℃. Based on the single factorexperiment, orthogonal test was carried out to optimize the medium. The results showed that theoptimal combination media contained2.0%sucrose,0.1%dipotassium phosphate and0.4%calcium carbonate. Using this optimium medium, the viscosity and polysaccharides productionof fermentation medium were2568.24mp.s and11.32mg/ml, respectively.Secondly, the polysaccharide of P. mucilaginosus was added in basal diets to test its effect ongrowth performance, immune organ index, mortality and intestinal bacteria diversity of poultry.According to the results, adding4.0g/kg polysaccharides significantly increased the averagedaily weight of chickens by9.57%and decreased the feed/gain by3.4%（P＜0.05） comparedwith control. At the same time, the mortality also decreased to a certain degree. Adding2.0g/kgand6.0g/kg significantly increased the daily weight, decreased the feed/gain during34weeksand the whole trial period （P＜0.05）. Compared with the control, adding2.0g/kg,4.0g/kg and6.0g/kg polysaccharides significantly increased the immune organ index of chickens. And thebest results were obtained for the group adding4.0g/kg polysaccharide, which enhanced thethymus index, spleen index and bursal index by22.49%,18.51%and23.81%, respectively. Theresults indicated that the polysaccharides of P. mucilaginosus could promote the development ofimmune organs in chickens （P＜0.05）. At the same time, the diversities of intestinal bacteria inthe chickens feeded with polysaccharide were analyzed using PCR-DGGE method. The BLAST result showed that adding2.0,4.0and6.0g/kg polysaccharides could decrease the number ofintestinal flora of chickens compared with the control. Among which, the population ofEnterococcus cecorum and Salmonella enterica subsp in cecum of chickens was found less in thegroup of2.0,4.0and6.0g/kg polysaccharides than that of the control, while no differenceexisted for the Lactobacillus johnsonii. It indicated that polysaccharide from P. mucilaginosushad some effects on the diversity of intestinal flora of chickens, however, the comprehensiveeffects need further qualitative and quantitative analysis.In conclusion, the optimium medium was obtaind for P. mucilaginosus to producepolysaccharide. Feeding the chickens with4.0g/kg polysaccharide, average daily weightsignificantly increased and the feed/gain decreased （P＜0.05）, which indicated the potentialapplication in feed industry. The polysaccharide may play a good role in the regulation of theimmunity system and the intestinal bacteria in chickens, which needs further experiment. |
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