Strains On The Selection Of Major Fungi Producting β-mannanase And Study Of Straw Degradation

P-mannanase is a kind of new enzyme preparations, belongs to hemicellulose enzymes, widespread in nature.At present, P-mannanase has been widely application:foodstuff, medicine, papermaking, textile, oil exploitation, biotechnology and so on.β-mannanase microbial sourcing has many distinguishing feature:high activity, low cost, facilitate extraction, broader role in pH, temperature range and substrate specificity. P-mannanase is a great development prospects new feed additive.Straw has high nutritional value, maked straw for livestock feed is a common method, but there are not easily decomposition macromolecules, serious shortage of minerals and vitamin, bulky, coarse texture, bad palatability, difficulty digestion, poor nutritional quality,less nutrients direct using. If taking some reasonable processing improves the nutritional value, straw will be the main energy feed.Most macrofungi belong to myceteae, basidiomycota, a few of macrofungi belong to ascomycota. At present, the research of macrofungi β-mannanase is little, our country is nearly in blank stage.In this study, determine the24macrofungi producing β-mannanase, this macrofungi are provide with the Northeast Forestry University Microbiology Laboratory.Screening10strains producing β-mannanase, by the Congo red plate screening method; making enzyme activity curves and determining straw powder composition by quantitative method, screened a strain that has a high yielding P-mannanase, degradation of straw is the strongest, needlemushroom(Flammulina velutiper (Fr.) Sing.).By improving the conditions of P-mannanase production, The best fermentation conditions of this strain produced β-mannanase is:the best pH is6.0, enzyme activity is2.16U/mL; the best culture temperature is25℃, the best cycle is5d, enzyme activity is2.52U/mL; the best carbon source is locust bean gum, enzyme activity is2.6U/mL; the best nitrogen source is yeast extract, enzyme activity is2.1U/mL.The analysis of characterization of β-mannanase crude extract prove:optimum react temperature is40℃, it has high enzyme activity between30℃to50℃, has lower heat resistance; optimum react pH is6.0, it has wider stability region, enzyme activity is more constant between5.0to9.0, relative enzyme activity has remained above85%; Ca2+and Li+has stronger enzyme activation for β-mannanase; obtained Km by Linewear-Burk double reciprocal plot method, Km is14.1g/L by konjac powder as substrate, regression equation is Y=3.28X+2.29, Km is10.4g/L by guar gum as substrate, regression equation is Y=3.97X-3.95. This data indicate that β-mannanase has a very good fit with the enzymatic properties, be fit for feed industry, having a good prospect.The straw that dealed with cultivating flammulina velutipes was usual forage, milk high output, intel lab, low cost,it can be usual forage substitute for basic fodderconcentrates, if the large number untapped straw deal with cultivating edible fungi was forage, can bring immeasurable economic benefits, and it has huge promotion effect To our economic and social development.