Isolation and Identification of Methylotrophic Bacteria Producing Methanol Dehydrogenase from Human Feet and Mouth

Abstract

The human feet and mouth are known as sources of methylated sulfides, which are produced by other microflora. Methylated sulfides could be oxidized by methylotrophic bacteria, which may result in odor reduction in human feet and mouth. In this study, we collected a total of 21 isolates from human feet, and 37 isolates from human mouth. These isolates were identified with biochemical test such as oxidase and catalase test and Gram staining assay. The presence of mxaF gene of methanol dehydrogenase was detected by PCR using specific primers. However, the result showed that most of the isolates did not possess mxaF gene. Hence, the methanol dehydrogenase (MDH) activity was also determined. From the total 21 isolates obtained from the feet, only 15 of them showed MDH activity whereas 23 isolates from the total 37 isolates obtained from teeth and tongue region also showed MDH activity. Isolate K25-3 (74.444 U/ml), K33-6 (79.815 U/ml), and K43-5 (69.259 U/ml) from human feet and M41L3 (135.926 U/ml), M27G2 (85.556 U/ml), and M51G1 (103.333 U/ml) from human mouth showed the highest total enzyme activity. Isolates with the highest total activity could be used for further studies such as purification of the enzyme and isolates characterization.

Methanotrophy, Methylotrophy, the Human Body, and Disease

“…Isolation of strains for characterization has been a core part of microbiology for over 100 years, and, while it is not as fashionable as metagenomics, etc., it is entirely necessary for obtaining evidence on enzyme biochemistry, evolution, etc., and some of the human-associated methylotrophs in pure culture are very well characterized, but we do not have genome sequences yet for any Methylorubrum podarium strains, for example. It is worth noting that there are a lot of studies in the last decade that produce a large number of isolates without any identification or characterization (e.g., feet and oral isolates from Waturangi et al (2011) that were isolated on 24 mM methanol), and while these libraries of organisms might be very useful to the community, it is really critical that proper identifications are made and deposits into international service collections are made before strains are lost.…”