Screening And Fermentation Optimization Of Pectinase Producing Bacteria And Its Application In Bio-degumming For Banana Pesudostem

Banana had been planted in Hainan Province with a large area. Annually, a great deal of banana pesudostem has been produced. However, all these banana pseudostem were abandoned. It was a renewable resource and could be used to extract banana fiber. Banana fiber could be used to produce paper and texile. So, the use of banana pseudostem could broaden the range of natural resources that human being could use. The abandoned agriculture by-product could be reused.Rotten banana pesudostem, soil which near the banana and the root of banana were used to screen the strain which could produce pectinase in this study. After first screening,265strains had been isolated with selective medium which pectin were used as sole carbon source. According to the transparent zone of all these265strains,41strains were selected. After the measurement of pectinase activity with3,5-dinitrosalicylic acid,13strains which were capable of producing pectinase had been determined.2strains which top the list of all selected strains were utilized to analyze the sequence of16S rDNA. When16S rDNA had been sequenced, phylogeny had been constructed,2strains both belong to Bacillus. The label of these two strains were25and29. These two strains were named as Bacillus sp. ZLXH-5and Bacillus sp. ZLXH-6respectively. The accession number of these two strains in GenBank were KM823927and KM823928respectively.Through fermentation optimization of Bacillus sp. ZLXH-5and Bacillus sp. ZLXH-6. The fermentation parameters had been determined. For Bacillus sp. ZLXH-5, the optimum fermentation time was2d, temperature was37?, pH values was5and rotary speed was180r/min. For Bacillus sp. ZLXH-6, the optimum fermentation time was2d, temperature was34?, pH values was5and rotary speed was150r/min. Bacillus sp. ZLXH-5was the best one to produce pectinase based on its pectinase production. When research focused on the effects of glucose concentration on pectinase production about Bacillus sp. ZLXH-5, it was found that when the glucose concentration was15g/L, the pectinase production reached the highest level, its prodution was3401.8U/mL. According to the pH value measured after fermentation, from5g/L to25g/L, when rising glucose concentration, pH value went down. Maybe when the glucose concentration rose, it accelerated the speed of bacteria to produce acid matters. Besides, After the exploration of the best pectin concentration for Bacillus sp. ZLXH-6, when the pectin concentration was5g/L, the pectinase production of Bacillus sp. ZLXH-6reached the highest level. The ezymatic properties of crude emzyme which produced by Bacillus sp. ZLXH-5was investigated, the optimum temperature for crude enzyme was55?. The pH value was8.5. Different ions caused different effects on crude emzyme. K+showed slight inhibition in pectinase activity of crude emzyme. Mn2+, Zn2+Fe2+, Cu2+would significantly inhibit the pectinase activity of crude emzyme. While Ca2+would greatly improve the pectinase activity of crude emzyme. All these parameters have great reference value for the application of crude emzyme.Banana pesudostem were treated with Bacillus sp. ZLXH-5and Bacillus sp. ZLXH-6, through the process of bio-degumming, the bio-dgumming efficiency of Bacillus sp. ZLXH-5was prior to Bacillus sp. ZLXH-6. Compared the bio-degumming efficiency of Bacillus sp. ZLXH-5in different culture mediums, the best bio-degumming medium was the pectinase producing medium which contained no pectin. While the pectinase producing medium contained pectin was not as efficient as the former one. So did the medium with beef extract and peptone. The photos taken by SEM showed that the surface of banana fiber which treated by Bacillus sp. ZLXH-5were smoother than the raw materail. It was also better than the banana fiber treated by Bacillus sp. ZLXH-6in pectinase producing medium which contained no pectin medium. It suggested that Bacillus sp. ZLXH-5had the potential to degum banana pesudostem. Thermal analysis of the raw material and treated banana fiber showed that the stability increased after the banana pesudostem treated. That might be the hemicellulose which were easier to be decomposed had been removed by Bacillus sp. ZLXH-5.