Diversity Analysis Of Prokaryotic Microorganism In The Solar Saltern Of Concentrated Seawater From Desalination

Coastal solar salterns have the stable and unique ecosystems.The concentrated seawater from desalination discharge into solar saltern for salt production would have a certain influence on the ecosystem stability and sustainable development of solar saltern.In this paper,the researches are performed on the diversity of culturable microorganisms and environmental microorganisms in the coastal solar saltern of concentrated seawater from desalination.Firstly,the stable prokaryotic microbial consortium was isolated from the crystallization pond of solar saltern.The osmotolerance and prokaryotic microbial diversity of five halophilic microbial consortia enriched under different salinity conditions were determined by the methods of the release yield of compatible solutes and Illumina high-throughput sequencing,respectively.A total of 735,811 effective sequences were obtained by sequencing 16S rDNA of five microbial consortia,which were classified into 65,644 OTUs.These OUTs were classified into 2 domains,7 phyla,20 classes,39 orders,65 families,and 106 genera.Under high salinity conditions,Halorubrum was the dominant genus,and Marinobacter gradually became the dominant genus with the decrease of salinity.A total of 13 genera appeared in all 5 samples and more than 25%of OTUs have not been clearly classified to the order,family,and genus levels.Under moderate salinity conditions,the microbial community structure changed significantly.The compatible solute release of the consortia was the highest at the salinity of 30%,followed by 15%,indicating that the microbial consortium had the higher osmotolerance.Secondly,the microbial diversity of ecologically modified coastal solar saltern of concentrated seawater from reverse osmosis(RO)desalination was studied by temperature gradient gel electrophoresis(TGGE)and sequencing technology.The difference of prokaryotic microorganism diversity and structure community were analyzed in a serial of ponds with different salinity of control groups and experimental groups in different seasons.The results indicated that the prokaryotic microbial diversity of the low salinity salt ponds of experimental group was better than the control group,but the microbial diversity in the middle and high salinity salt ponds had not changed significantly.The dominant bacterial sepcies were Spiribacter sp.,Paracoccus sp.and Bacillus litoralis.The dominant archaeal species was the genus Halogeometricum sp.,which only detected in high salinity ponds.The bacterial diversity in summer was higher than in spring and autumn.As the salinity gradually increasing,the Spiribacter aquaticus gradually dominated.Finally,the microbial diversity and community structure of different salinity ponds were analyzed in different seasons of coastal solar saltern of concentrated seawater from low-temperature multi-effect(LT-MED)desalination.The results indicated bacteria and archaea were not detected in the concentrated seawater after the process of seawater desalination and bromine production,respectively.The bacterial diversity showed little change in the samples at different month and salt ponds,and the dominant bacterial species were mainly Spiribacter salinus and Pseudoalteromonas sp..Archaea is only detected in the pond of No.VII with the highest salinity,and the dominant archaeal species was mainly Halogeometricum sp..The bacterial community structure was relatively stable in spring and summer,and changed obviously in autumn.The bacterial community structure changed greatly in ponds with different salinity,and S.salinus gradually replaced Pseudoalteromonas sp.with the gradual increase of salinity and became the dominant bacterial species.