Taxonomic and Functional Comparative Metagenomics of Peruvian Salterns: Insights into Microbial Communities and Aminotransferase Potential

Metagenomic analysis of extreme environments is essential in biotechnological research. This work aimed to determine and compare the microbial diversity of two Peruvian saline environments and characterise their functional profiles. Soil metagenomic DNA (mDNA) was analysed from Maras and Pilluana salterns, both with a thalassohaline origin but with different geographical and environmental conditions. Maras samples exhibited more diversity and a remarkably higher abundance of archaea (phylum Euryarchaeota). The most dominant bacterial phyla across all the samples were Pseudomonadota and Actinomycetota. Multiple pathways specific to archaea were more abundant in Maras, as were pathway-related synthesis and degradation of compatible osmolytes such as glycine betaine and ectoine. The most abundant pathways in Pilluana were associated with fatty acid biosynthesis and oxidation. A total of 49 and 47 metagenomic-assembled genomes (MAGs) were retrieved from Maras and Pilluana samples, respectively. Bacterial MAGs were mainly classified within the phyla Psudomonadota, Actinomycetota, Planctomycetota, and Gemmatimonadota. Additionally, a total of 20 putative aminotransferases class III (ATs, PF00202) from Maras3 were cloned and expressed in E. coli Rosetta, and their substrate scoping was assayed against several aldehyde and ketone substrates; AT pQR3082 and pQR3090 showed unique broad substrate acceptance for aromatic and aliphatic substrates. Our study provides new insights into the microorganisms and metabolic pathways of these unique extreme environments, highlighting the promising biotechnological potential of metagenomic ATs.