RESUMO
Mycobacterium hassiacum is so far the most thermophilic among mycobacteria as it grows optimally at 50 °C and up to 65 °C in a glycerol-based medium, as verified in this study. Since this and other nontuberculous mycobacteria (NTM) thrive in diverse natural and artificial environments, from where they may access and infect humans, we deemed essential to probe M. hassiacum resistance to heat, a strategy routinely used to control microbial growth in water-supply systems, as well as in the food and drink industries. In addition to possibly being a threat in its own right in rare occasions, M. hassiacum is also a good surrogate for studying other NTM species more often associated with opportunistic infection, namely Mycobacterium avium and Mycobacterium abscessus as well as their strictly pathogenic counterparts Mycobacterium tuberculosis and Mycobacterium leprae. In this regard, this thermophilic species is likely to be useful as a source of stable proteins that may provide more detailed structures of potential drug targets. Here, we investigate M. hassiacum growth at near-pasteurization temperatures and at different pHs and also characterize its thermostable glucosyl-3-phosphoglycerate synthase (GpgS), an enzyme considered essential for M. tuberculosis growth and associated with both nitrogen starvation and thermal stress in different NTM species.
Assuntos
Proteínas de Bactérias/metabolismo , Glucosiltransferases/metabolismo , Mycobacteriaceae/crescimento & desenvolvimento , Mycobacteriaceae/genética , Proteínas de Bactérias/genética , DNA Bacteriano/genética , Glucosiltransferases/genética , Concentração de Íons de Hidrogênio , Mycobacteriaceae/metabolismo , Micobactérias não Tuberculosas/genética , Micobactérias não Tuberculosas/crescimento & desenvolvimento , Micobactérias não Tuberculosas/metabolismo , Pasteurização , TemperaturaRESUMO
Among 28 mycobacterial species studied, only Mycobacterium tuberculosis, M. bovis, M. africanum, M. marinum, M. kansasii, M. gastri and M. ulcerans produced waxes yielding long-chain beta-diol components (called phthiocerol and companions) and polymethyl-branched fatty acids on saponification. The same mycobacterial species also produced diesters of phenol phthiocerol and companions. Fatty acids esterifying these fatty alcohols in M. marinum and M. ulcerans were found to belong to the phthioceranic series (dextrorotatory fatty acids), in contrast to those of the other species (laevorotatory fatty acids called mycocerosic acids), both groups having the same chain length and methyl-branched positions. M. kansasii and M. gastri contained the same waxes with identical structures, as did M. tuberculosis, M. bovis and M. africanum. Neither the type strain of M. tuberculosis, nor that of M. bovis or M. marinum accumulated the strain-specific phenolic glycolipids.