Horizontal And Vertical Distribution Of Magnetotactic Bacteria In The Sediments From Wudalianchi Volcanic Barrier Lake

Microorganisms have a certain geographical distribution pattern on the global scale.The diversity and distribution of microorganisms are closely related to their living environment.Various environmental factors,such as latitude,total nitrogen,total carbon,salinity,and pH,may affect the distribution of microorganisms.Magnetotactic bacteria(MTB)are a kind of microorganisms that can be orientated along the direction of the magnetic field.It is widely distributed in different aquatic and terrestrial environments such as oceans,lakes,and soils.Current studies have found that MTB have a certain distribution pattern around the globe,and salinity may be one of the control factors that cause differences in the distribution and diversity of MTB.At the regional scale,the vertical distribution of MTB has been studied.It was found that nitrates or other nitrogen oxides may play an important role in the vertical distribution of MTB in deep sea and semi-deep oceans.The current research on MTB diversity mainly focuses on freshwater and marine sediments.There are few studies on MTB in volcanic barrier lakes sediments,and systematic studies on the diversity and distribution of MTB on the smaller scale area are lacking.Volcanic barrier lakes can be divided into open water body,semi-enclosed body,and enclosed body of water in Wudalianchi,and the pH span between different water lakes is large and contains rich iron and sulfur elements.Therefore,we selected eight volcanic barrier lakes as research sites,collected MTB in horizontal and vertical scales,used scanning electron microscopy to observe the morphological diversity of MTB,and used high-throughput sequencing to analyze the phylogenetic diversity of MTB.At the same time,we investigated the MTB distribution on horizontal and vertical scales in different water bodies,different lakes of the same water types,and different locations of the same lake.Combined with the corresponding environmental factors,the effect of environmental factors on the horizontal and vertical distribution of MTB was studied.The results of morphological diversity of MTB in Wudalianchi volcanic barrier lakes have shown that the MTB morphology is diverse,including spherical,rod-shaped,fusiform,hollow spheres,and multicellular magnetotactic prokaryotes(MMPs).The shuttle and hollow spherical have not been reported in the current study,and we need further study.The analysis of horizontal and vertical distribution of MTB in lakes of different types of water body shows that the similarity of species composition and abundance of MTB on the horizontal scale in lakes of different types of water increases with the lake from south to north.The community diversity of MTB on the vertical scale showed a downward trend.Proteobacteria plays a leading role in horizontal and vertical scale,and Acinetobacter occupies the dominant genus at the horizontal and vertical scales.In different types of water body,the spatial distribution of MTB are mainly driven by sulfides,ferrous irons and total phosphorus.The analysis of horizontal and vertical distribution of MTB in different lakes of the same type of water body showed that the community diversity and species abundance of MTB on the horizontal scale were different.The community diversity of MTB in semi-enclosed water body on the vertical scale showed a downward trend,while the species composition and abundance showed an upward trend.Proteobacteria and Thaumarchaeota dominate the horizontal and vertical scale of the phylum,while Magnetococcus and Acinetobacter occupies the dominant genus at the vertical scale.In different lakes of the same type of water body,the spatial distribution of MTB are mainly driven by ferrous irons,salinity and pH.The horizontal and vertical distribution of MTB in the same lake and different sites showed that the community diversity and species abundance of MTB in Sanchi,Yueyapao and Yaoquanhu were different at both horizontal and vertical scales.Proteobacteria and Woesearchaeota_[DHVEG-6]are dominant phylum at horizontal and vertical scale.There are differences on the genus of species communities in different sampling sites in Sanchi,Yueyapao and Yaoquanhu,mainly some uncultured bacteria dominant.The spatial distribution of MTB are mainly driven by soluble total iron,total phosphorus and pH.In summary,MTB in Wudalianchi volcanic barrier lakes has a certain distribution pattern in smaller scale area.Among them,fusiform and hollow spherical MTB were found in morphological diversity.MTB is affected by water body types on horizontal and vertical distribution at smaller scale area.Proteobacteria plays a leading role in MTB phylum level,and Woesearchaeota_[DHVEG-6]and Thaumarchaeota also account for a large proportion.Magnetococcus and Acinetobacter occupy the dominant position in MTB genus level.In the Wudalianchi volcanic barrier lakes,MTB is mainly affected by pH at the horizontal scale,and is most affected by ferrous irons,sulfides and total phosphorus at the vertical scale.