Isolation, Screening, Indentification Of Bacillus Strain Producing Phytase And Feeding Value To AA Chicken

More than40samples were collected from different area of Henan province, firstly,they were treated for30minutes with80℃water, then the Bacilli producing phytasewere isolated on the medium with phytin as substrate. The strains formed spore werescreened by microscope, and the high phytase producing strains were selected by platculturing method. Furthermore, excellent strains were screened by high temperature andlow pH. The phytase activity of the strains selected was determined by ammoniummolybdate method. Lately, they were identified by the colony, morphology, microscopicmorphology in combination with the physiological and biochemical feature and16SrDNA sequence.The Bacilli strains were made powder production by specific process, after theywere proved to be safe in mice by oral administration, the feeding value wereinvestigated by oral administrating AA chicken. A total of240one-day-old AAchickens were allocated to four groups, three replicates per group and20chickens perreplicates. A commercial corn-soybean meal diet was the control diet, and diets with107CFU/g feed,10~8CFU/g feed and10~9CFU/g feed compound Bacillus production wasformulated respectively. The trial period was42days. The feeding effects of the strainswere evaluated by growth performance, antibody titers to New Castle Disease Virus,immune organ index, gastrointestinal microbial population and Phosphorus excretionafter the strains were oral administrated AA chicken. So, it has laid a good theoryfoundation as a probiotics feed additives.The results showed that10strains producing phytase were isolated from differentsamples, and all of them could form spore. Three strains of B.Phy2, B.PHy3andB.PHy9were screened because they could tolerate high temperature and low pH. Mostimportantly, the phytase activity of the three strain were152U/mL,172U/mL and2011U/mL. The results also indicated that the three strains were identified as Lysinibacillus sphaericus, Bacillus cereus and Bacillus sp. Toxicity tests showed thatthey were safe to mice after oral administration.The animal feeding test results showed that the average day gain(ADG) of testgroups could be improved（P<0.01）, but it was most significant of low-dose group Ⅰand middle-dose group Ⅱ. The feed consumed/gain of the middle-dose group Ⅱ was best（P<0.05）, but that of low-dose group Ⅰ and high-dose group Ⅲ had no differencethan control group（P>0.05）. There were no significant difference on ADG among allof groups in22~42day-olds（P>0.05）, and only the feed consumed/gain of themiddle-dose group Ⅱ was decreased（P<0.05）. In the whole trial period, the ADG oflow-dose group Ⅰ and middle-dose group Ⅱ had be obviously increased（P<0.05）thancontrol group, and only the feed consumed/gain of the middle-dose group Ⅱ wasdecreased（P<0.05）. There were no different on immune organ index among allgroups（P>0.05）, and the same results to New Castle Disease Virus（P>0.05）, butthere was the rising trend in the two parameter. In gastrointestinal microbial population,the number of Lactobacillus and Bifidobacillus of middle-dose group Ⅱ could beimproved significantly (P<0.01) than control group on21day-old, the number of E.coliof all trial group were decreased (P<0.01). But they were difference on42day-old, thenumber of Lactobacillus of all trial group were improved (P<0.01), and Bifidobacillus(P<0.05), E.coli (P<0.01). Most significantly, the phosphorus content in faeces of alltrial groups were decreased significantly than control group (P<0.01), and the middle-dose group Ⅱ was the best.