Diversity of cultivated methylotrophs from the extremely oligotrophic system in the Cuatro Cienegas Basin, Mexico: An unexplored ecological guild

Abstract

The simplest form of heterotrophy in the carbon cycle is to metabolize C1 compounds, this is a widely spread strategy that includes genus in different phyla inhabiting diverse environments that seem to have acquired the methanol dehydrogenase by horizontal gene transfer (HGT). The objective of this study was to isolate and explore the diversity of the ecological guild of methylotrophs in the water and riparian vegetation of the Churince system in the Cuatro Cienegas Basin (CCB), Coahuila, Mexico. Methylotrophy was verified by polymerase chain reaction (PCR) amplification of the mxaF gene that encodes the α-subunit of the enzyme methanol dehydrogenase (MDH), while phylogenetic affiliations were assigned following 16S rRNA phylogenetic analyses. Among the isolated strains we observed a phylogenetic association with a common species of Methylobacterium (M. radiotolerans). In addition, other methylotrophs were isolated, like Methylorubrum aminovorans, Methylorubrum extorquems and Methylophilus methylotrophus. Interestingly, we also isolated other strains able to grow in methanol and mxaF+, their 16S rRNA identified them as Jiella, Pseudomonas, Rhizobium, Serratia and Stenotrophomonas. This study addresses, for the first time, the diversity of cultivated methylotrophic bacteria within CCB and inserts this knowledge in the context of a total inventory of the microbiota in the site.