Screening And Identification Of Sargassum Spp.-degrading Microbe And The Initial Evaluation Of Degradation

Sargassum is a common type of large brown algae,which belongs to Sargassaceae,Sargassum and is widely distributed in the South China Sea.Sargassum,which has high economic value,is an important kind of fertilizer,fodder and industrial material.In industry,physical and chemical degradation methods are often used to degrade sargasso,while there are some disadvantage about those techniques such as energy dissipation and environment pollution.Due to high efficiency and friendly environment,biodegradation has become the research focus and also has been the mainly method,especially using cellulose lyase and alginate lyase produced by microorganism.However,nowadays the microorganisms that reported have ability to degrade Sargassum algae is single variety and poor enzyme-production ability,and is difficult to meet the needs of industrial production.In order to lay the foundation for processing and utilizing the Sargassum,this study aims at isolating and identifying fungi that have cellulose degradation ability and bacillus that has alginate degradation ability,and study on sargassus-degrading effect of those microorganisms.The specific results are as follows:Sample was isolated from mangrove sediment in Dongzhaigang mangrove protection zone in Hainan,China.By using the method of selective isolation by warm water bath at 80?,301 strains bacillus were selected.Then,utilizing alginate as the sole carbon source to cultivate those bacillus,16 strains showed larger diameter ratio of hydrolysis ring and colonies(D/d?6).By the determination of activity of alginate lyase,strains HB12124?HB12265 and HB12274 showed higher enzyme-activity as 1.99 U/mL?2.11 U/mL?2.22 U/mL,respectively.The result of the morphological an physiological observation,16S rDNA sequencing and phylogenetic analysis revealed that the strains belongs to be genus Bacillus,HB12124 was Bacillus amyloliquefaciens subsp.amyloliquefaciens,HB 12265 was Bacillus sp.HB12265,HB 12274 was Bacillus amyloliquefaciens subsp.plantarum,respectively.A total of 102 fungi strains were isolated from mangrove sediment by selective medium with ampicillin and streptomycin.Then,utilizing carboxyl methyl cellulose(CMC)as the sole carbon source to cultivate those fungi,15 strains showed larger diameter ratio of hydrolysis ring and colonies(D/d>6).By the determination of activity of CMCA and FPA,strains HF15162,HF15172 and HF15195 showed higher enzyme-activity.The CMCA is 5.06 U/mL,10.34 U/mL and 11.11 U/mL,respectively,and the FPA is 1.84 U/mL,1.99 U/mL and 1.76 U/mL,respectively.The results of the observation of conidial fructification and colonial morphology,ITS sequencing and phylogenetic analysis revealed that strain HF15162 was Cephalosporium sp.HF15162,strain HF15172 was Daldinia eschscholtzii and strain HF15195 was Phanerochaete sordid.Strains HB12274 and HF15172 were cultured by fermentation medium using sargassum power as carbon source.The results showed that:the solid weight-lossing rate of strain HB 12274 and HF15172 was 11.02%and 25.19%,and the increasing amount of reducing sugar in fermentation broth was 13.12?g/mL and 11.84?g/mL,respectively.Then,utilized fronds and small branchs of sargassum as the fermentation medium to subcultured the strains above.The results showed that strain HB 12274 and HF15172 had no degradation effect to sargassum branch but obvious effect to the frond.After degradation,the fronds were incomplete,clearly gaps at edge,epidermis cells dissolve and disappear,cortical cell and myelocyte exposure,and serious degradation fronds were appears perforation and breakage.