Analysis Of The Adaptability Of Haloalkaliphiles To Extreme Environment

Haloalkaliphiles are types of extreme microorganisms that can grow,develop,and reproduce in high-salt and extreme-alkaline habitats.The optimal growth salinity must be higher than 0.5 mol·L^-1,and the optimal growth pH is greater than 9.0.For decades,the unique way of life of Haloalkaliphiles has attracted widespread attention,the research on them has made tremendous progress:from the analysis of its life mechanism to the application of its high potential new enzymes and compounds for industrial production,plus to the understanding of their role and ecological function in the environment.With the update and advancement of genome sequencing technology and equipment,cheap,fast,efficient and accurate access to the gene sequence of Haloalkaliphiles and the metagenomic composition of saline-alkali comunity has accelerated our life Comprehensive understanding of the mechanism,production applications,and ecological functions.The moderately halophilic and alkalophilic aerobic bacterium Alkalicoccus saliphilus DSM 15402^T, was stored in the refrigerator of the research group.Here,we report the draft genome of strain DSM15402^T,which consists of approximately 3.52 Mb.Among the 3434 predicted genes,some genes dedicated to ensuring intracellular osmotic balance were identified,offering the valuable insight into specific adaptations to the extreme environment.The other haloalkaliphilic bacterium Alkalicoccus halolimnae BZ-SZ-XJ29T isolated from the salt lake sediments of Xinjiang Uygur Autonomous Region,China.The draft genome size is about 3.66 Mb and contains 3,534 predicted genes.We analyzed and identified some genes related to osmotic balance and acid-base balance in a strong alkali environment,providing insights into specific adaptations to the double extreme environment.Analysis of the structure of saline-alkali bacteria is significance for understanding the ecological diversity of saline-alkali and its function and utilization of saline-alkali resources.We took the saline-alkali soil in the Songnen Plain as the research object,and analyzed the bacterial community structure through Illumina Miseq sequencing.We found that:The sequencing depth curve was almost smooth with the increase of the number of samples,and it was well represented.We found the diversity index analysis that the community diversity of DC11 and DC2 was the highest and the lowest;We obtained a total of608443 sequences by sample sequencing,these sequences could be divided into 26 phylums,423 families845 genera:Actinobacteria（47.30%）,Proteobacteria（30.32%）,Chloroflexi,Gemmatimonadetes,Bacteroidetes,Firmicutes,and Acidobacteria are the main phylum（total 97.76%）.Based on the difference of the family distribution of 21 samples,the samples were divided into 3 groups by principal component analysis and clustering heatmap.In the group,the results obtained by the two methods were highly consistent,and HCO₃^-,Total Salt,Na⁺,and pH were found to be significant environmental factors in the redundancy analysis.The saline-alkaline community of the Songnen Plain is rich and diverse,and has gigantic research potential.The composition types and relative contents of archaeal iGDGTs not only indicate changes in environmental conditions,but are also closely related to the structure and ecological function of archaeal community.We determined the community structure of saline-alkali archaea in the Songnen Plain by high-throughput sequencing and combined with high performance liquid chromatography?mass spectrometry to analyze iGDGTs.The results showed that the main components of iGDGTs were iGDGT-0,iGDGT-4,and Crenarchaeol,indicating that the iGDGTs without cyclopentyl ring or with high number of cyclopentyl ring in soil might be more stable and could accumulate in soil for a long time;The correlation analysis between iGDGTs and environmental factors showed that the main environmental factors driving iGDGTs are pH、TN、NO₃^-、HCO₃^-、Na⁺、Total Salt.pH、TN、NO₃^-、HCO₃^-are positively correlated with iGDGT-0 and negatively correlated with iGDGT-4 and Crenarchaeol,Na⁺and Total Salt are negatively correlated with iGDGT-0 but positively correlated with iGDGT-4 and Crenarchaeol;Finally,network analysis showed that the microbial source of iGDGT-0 was family2（Haloferacaceae）and Class1（Halobacteria）,and the microbial source of Crenarchaeol was Genus8（uncultured archaeon）.Through the analysis above,the distribution characteristics of iGDGTs and their corresponding relationships with environmental factors were found,the structure of archaea community were analyzed,and the microbial source of the iGDGTs was ascertained.