Slope aspect influences soil microbial community structure and composition in the Israel arid Mediterranean

Microbial biogeographical patterns in Mediterranean ecosystems are becoming widely documented; however, the influences of slope aspect on the microbial community composition and structure are poorly understood. This study tested the hypotheses that slope aspect and organic matter content would influence microbial diversity patterns and distribution. Sets of five soil samples were collected from different slope aspects (north slope, south slopes, and valley bottom) and bacterial and fungal communities were examined using the 16S rRNA gene and ITS1 region sequencing, respectively, on the Illumina HiSeq platform. Organic matter and soil moisture varied significantly across all sites but did not influence microbial diversity patterns. Community structure (Bray-Curtis dissimilarity) indicated that each site had a distinct microbial community, and soil moisture along with organic matter modulated the community structure. Relative abundance of key bacterial taxa (Actinobacteria and Bacteriodetes ) and fungal taxa (Ascomycota was significantly influenced by slope aspect. Our results show, for the first time, that the often reported slope aspect dynamics of the soil microbiomes do in fact influence bacterial and fungal community composition and structure. Overall, taken together with previous studies from the region, this study provides novel insight on the physio-chemical properties that modulate the biogeographical patterns of soil microbes and contributes to our knowledge of factors that mediate microbial ecology in Mediterranean ecosystems.