Study On Isolation,Identification And Characteristics Of Gossypol Decomposing Strains

Cotton is the main economic crops in Xinjiang,the data that,the planting area of Xinjiang region of 31.51 million mu,annual crop yield of 7 million tons,and cotton stalk output reached 6.5million tons.Cotton stalk is a very great renewable plant protein feed resources of the higer levels of protein and nutrients. However, because of the cotton plants contain toxic free gossypol, harmful to animal growth and reproduction,which limits their usefulness and usage in feed, resulting in waste of feed resources. Presently,the degradation of toxic gossypol methods are physical,chemical and biofermentation methods. Although physical and chemical detoxification methods played a certain role, but there are also exist some disadvantages such as the high cost,easy to damage of nutrients. The method of microbial fermentation not only can detoxificated cottonseed meal, but also can improve the nutritional and application value of cottonseed protein,so far biological fermentation is considered the safest,most effective detoxification method with a low cost.1.In this study,common isolated 14 strains,and gossypol acetic acid as sole carbon source, isolated 6 strains having decomposition ability of gossypol from cotton stalk,numbered A1,A2,A4,B1,B2,B9. 2 highly gossypol decomposing bacteria were screened out by gossypol resistance test. The test results showed that strain B1 and B9 grows well on different concentration gossypol acetate as sole carbon source of solid plates. From the NA plates showed: B1 colonies both sides color is consistency、round、edge irregular、milky、surface wrinkles and wetting、center slightly uplift、transparency;The cell shape of B1 was rod,with size of 1.27~2.30μm,uniform coloring、can produce oval spores、Gram-positive; B9 colonies round、yellowish、edge irregular、opaque;B9 bacterial cells is about 1.26 ~ 2.69μm,evenly colored、Gram-positive;Therefore,the strains preliminarily identified as Bacillus. By the Biolog Microbial Identification System to its molecular identification,the results showed that strain B1 and B9 belong to the genus Bacillus, species names are Bacillus vallismortis and Bacillus mojavensis,respectively.2. Using HPLC method to determine the total gossypol and free gossypol content of cotton by-products(cotton stalk、cottonseed meal、cottonseed cake、cottonseed oil、etc). Discussion of gossypol content of each sample brought from Turpan,to provide reference data for future study. HPLC detect results show that the total gossypol and free gossypol content of cotton stalks for 0.02% and less than0.8μg / ml;cottonseed meal 1.66% and 5949.8 mg / kg;cotton cake 0.68% and159 mg / kg;unprocessed cottonseed oil the 2.50% and 8033.5 mg / kg;the total gossypol in edible cottonseed oil was not detected, the content of free gossypol≤0.25 mg / kg; the total gossypol and free gossypol content in the cottonseed oil sludge 5.23% and 30796.5mg/kg. Detoxification test results show that the same of inoculum and culture temperature strain of B1 and B9. when the shaking culture of cottonseed detoxification rate of 21.1% and 22.2%, respectively.But the detoxification of cottonseed oil sludge effecy is not obvious.3.gossypol decomposing bacteria mixed culture with the high efficient lactic acid bacteria and cellulolytic bacteria in a 2% sucrose solution,and study of the individual bacteria and mixed bacteria growth characteristics,probe to whether exist inhibition effect between the these three species,and whether as a feed additive mixed. That test results shows,at the stable time when mixed culture of these tree strains significantly shorten than the stable tiem when single culture,which shows,these three strains between not only no inhibitory effect,but also to promote each other growth,to provide a theoretical basis for develop a new type of the mixed feed additive.