We investigated the species diversity of Mycobacteriaceae in surface water samples from six environments at the zoological park in São Paulo, Brazil. Three hundred and eighty isolates were cultivated and identified by phenotypic characteristics (growth rate and pigmentation) and sequencing of hsp65, rpoB and 16S rRNA genes. The results revealed that almost 48% of the isolates could be identified at the species level; about 50% were classified at the genus level, and only less than 2% of the isolates showed an inconclusive identification. The isolates classified at the genus level and not identified were then evaluated by phylogenetic analyses using the same three concatenated target genes. The results allowed us to identify at the genus level some isolates that previously had inconclusive identification, and they also suggested the presence of putative candidate species within the sample, demonstrating that this zoological park is an important source of diversity.

Over the past few decades, there has been a significant increase in the number of mycobacterial species described. Currently, the genus Mycobacterium consists of 170 species. Most species are called nontuberculous mycobacteria (NTM) and are potentially or rarely pathogenic and ubiquitous. One of the main challenges in mycobacteriology is the rapid and precise identification of these microorganisms. In this work, we compared two protein extraction protocols for the identification of 38 reference strains and clinical isolates, representing 27 species, by mass spectrometry (MALDI-TOF MS) to subsequently use the best method for identifying environmental mycobacteria. The results obtained with reference strains and clinical isolates showed that protocol A was effective in identifying 92.1% of mycobacterial specimens at the species level and protocol B, 50%. Therefore, protocol A was evaluated for the rapid identification of 27 environmental mycobacterial isolates. These isolates were subjected to PCR-restriction enzyme analysis (PRA-hsp65). Two isolates were misidentified by PRA-hsp65, whereas MALDI-TOF MS was able to identify them correctly. The results were confirmed by hsp65 and 16S rRNA gene sequencing. Mass spectrometry has the advantage of being a simpler and faster technique than PRA-hsp65, and our results showed that MALDI-TOF MS is a valuable tool for the identification of environmental mycobacterial isolates.

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