Study On Biological Characteristics Of Strains With High Inulinase Activity

Aspergillus niger M89, Asp. niger H8 and Aspergillus niger U y - 2 are all Inulinase high- yielding strains ,whose major biological characteristics have been studied in this paper . The research content includes the studies on morphology, major enzyme systems of the strains and the preliminary study of inulinase genes.For researching the morphologies of the strains.I had turned the strains respectively in Czapek, MEA, PDA and culture media that could assimilate nitrous acid salt to observe the characters of the morphologies of the colonies. At the same time the observation of the microscopical feature of the individual strain and the observation of the conidium of the strain by the scanning electronic microscope are done. According to the information we divide Asp.niger M89 and Asp. niger H8 into Aspergillus Genus , Aspergillus niger section Aspergillus awamori species. The mutant strain Asp. nigerU gamma - 2 can be divided into Aspergillus Genus , Aspergillus niger section Aspergill'i.s foetides species. The mutant makes the morphology of the colony changed greatly. A set of easy and high efficient methods used to identify the morphologies of the mould were set up through those studies.On the research of enzyme system produced by the strains, we had measured the growing curves of the inulinase, protease, amylase, amylase, and cellulose enzyme. Excepting the high yielding inulinase ,this three strains also have different levels in protease, amylase, pectinase, and cellulose enzyme. Among these , the production of the inulinase is higher than the others. Besides the inulinase activity of mutant strain Asp. niger U gamma -2 raised substantially, amylase and pectinase also have been obviously raised. For different enzyme of the same strain, the time is difference that reaches the highest enzyme activity. Followed to ferment time, protease, amylase, inulinase and pectinase reaches the highest enzyme activity. Cellulose enzyme has certain discrepancy because of different strains.According to the four kinds of sequence from Aspergillus niger strains reported by GenBank , primer are designed respectively, genomic DNA of these three strains are taken as mould, then PCR is carried out and nucleus sequence is to be measured next. Theresult of measurement and original sequence are analyzed, which proved that nucleotide sequence identities are not high , it is possible to draw a conclusion that gene sequence of mulinase from Aspergillus niger is different from that reported.