Study On The Diversities Of Bacteria In Intertidal Sediments Of The Fields Peninsula, Antarctica

In this paper,7 intertidal sediment samples collected from different geographical locations of Fildes Peninsula,Antarctia have been studied on the total bacterial counting,isolation and purification of strains,observation of bacterial colony and thallus,determination of 16S rDNA,and enzyme production status of strains.The aim is to understand the diversity of culturable bacteria in intertidal sediments of the peninsula.Meanwhile,in order to understand and compare the microflora and structure of bacterial groups in these samples,the high-throughput sequencing of 16S rDNA V4+V5 of samples are determined and analyzed.In addition,combined with the physical and chemical properties of samples and the environmental data,the relationship between bacterial community characteristics and environmental factors is compared.The results showed that:?1?The results of bacterial counting showed:On 2216E culture media,the bacteria content of 7 samples were QEC-1>QED-C1>SWWC-1>CCZ-C1>HJW-C1>NES-C1>NWZ.Among it,sample QEC-1 contained the maximum amount of bacteria?6.8×10⁶ CFU/g?,but sample NWZ had the least?2.2×10⁴CFU/g?.The numbers of bacteria counting on R₂A and M1 culture media were less than that of 2216E culture media.?2?The observation results of bacterial morphology showed:The colonies of bacterial colony were mainly white,milky white,yellow and orange and bacteria body were spherical,rod-shaped and short rod-shaped.18.7% isolated bacteria were G⁺ and 81.3%were G^-.This indicated that these culturable bacteria had a certain morphological diversity?3?The results of enzyme production showed:26%isolated bacterial strains had the ability to product amylase,47.2% isolated bacterial strains could produce protease,62.5% isolated strains could produce lipase,45.8% isolated strains could produce esculin hydroiase,25% isolated strains could produce gelatinase,34.7% isolated strains could produce cellulose,56.9% isolated strains could produce oxidase,and55.5% isolated strains could produce catalase.In these strains we found that some strains had stronger ability to produce enzymes such as amylase,casein enzyme,lipase,aesculin hydrolase,and catalase.These strains were concentrated on QEC-1?QED-C1?HJW-C1 samples.?4?The results of 16S rDNA sequencing showed that:79 strains were belong to 4phyla?Proteobacteria,Actinobacteria,Bacteroidetes,Firmicutes?,5classes?Gammaproteobacteria,Alphaproteobacteria,Actinobacteria_c,Flavobacteria,Bacilli?,22 genus and 31species.Proteobacteria was the dominant bacterium group?occupied 69.6% of all79 stains?.On the class level,Gammaproteobacteria was the dominant group.On the genus level,Pseudoalteromonas was the dominant group.Sample SWWC-1 had the highest diversity including 4 phyla,4 classes and 7genus.Samples NWZ,QED-C1 had the lowest diversity including 1phyla,2 classes and 3 genus.In addition,the 16S rDNA sequences similarities of 11 strains were between 97% and 98.5%,which means it could be new species.?5?The results of high-throughput sequencing showed that there were 45 phyla,104 classes and 442 species in the 7 samples.In these samples,the top ten phyla were Bacteroidetes,Proteobacteria,Firmicutes,Actinobacteria,Planctomycetes,Cyanobacteria,Acidobacteria,Verrucomicrobia,Chloroflex and Nitrospirae.The top ten classes were Flavobacteriia,Clostridia,Gammaproteobacteria,Betaproteobacteria,Bacteroidia,Sphingobacteriia,unidentified_Actinobacteria,Alphaproteobacteria Bacilli,and Planctomycetacia.On the genus level,Albidiferax,Granulosicoccus,Lactobacillus,Maritimimonas,Lutibacter and Massilia occupied a higher proportion,and while Granulosicoccus could been detected in all 7 samples.The results of Principal Component Analysis showed that:The distance between sample LSN.02,LSN.05 and LSN.07 were shot,whichindicated its similarity of microflora and structure were high more than other samples.On the other hands,sample LSN.01,LSN.06 and LSN.03 were far away from each other and other samples,which indicated its similarity of microflora and structure were low,and also indicated it were different from other samples.In addition to,sample LSN.03 was different from other samples on phyla,class and genus level,which could be due to the influence of human activities.?6?The analysis of the microflora and structure combined with the sample physicochemical properties showed that there were high relativity between TON?NH₄⁺-N?NO₃^--N?PO₄^3--P?NO₂^--N.And it had a big influence on the diversity of microflora and structure of LSN.02,LSN.04,LSN.05 and LSN.07 samples.On the other hand,TOC had a big influence on the diversity of microflora and structure in LSN.01,LSN.06 and LSN.03 samples.?7?The comparison between culturable method and high-throughput sequencing method showed that there were lot of differences on the dominant bacteria.On the phyla level and class level,the culturable bacteria were singleness?the preponderance groups were Gammaproteobacteria and Pseudoalteromonas?.But the results of high-throughput sequencing method were plentiful.In addition,on the phyla level,sample LSN.01and LSN.04 had same dominant bacteria groups as Proteobacteria in both methods.On the class level,sample LSN.01,LSN.02 and LSN.04 had same dominant bacteria groups as Gammaproteobacteria.On the genus level,the dominant microflora of every sample was different in both methods.On the whole,there had more diversities of microflora and structure in high-throughput sequencing method than culturable method,but the proportion of dominant microflora was lower than that of culturable method.In this study,we had a systematic understanding on the diversities of bacteria in intertidal sediments of field peninsula,Antarctia.The results can not only provide useful references for other similar studies,but also provide valuable strains of enzyme producing.