A genuine mycobacterial thermophile: Mycobacterium hassiacum growth, survival and GpgS stability at near-pasteurization temperatures

Abstract

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.

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches

“…Some NTM are thermotolerant, being able to optimally grow at 45 °C, such as M. xenopi , M. thermoresistibile , and M. phlei ; however M. hassiacum is the most thermophilic mycobacteria, being able to grow at temperatures between 30 and 65 °C [ 236 ]. M. hassiacum is capable to cause infection in humans [ 237 ] but is usually found in water distribution systems [ 238 ].…”

“…M. hassiacum is capable to cause infection in humans [ 237 ] but is usually found in water distribution systems [ 238 ]. The thermophilic behavior can be due to a down-regulation of trehalose biosynthesis at higher temperatures, high accumulation of free glucose as a potential carbon reserve for growth under more favorable conditions, and the thermostability of glucosyl-3-phosphoglycerate synthase responsible for the synthesis of the precursor of glucosylglycerate, a metabolite involved in mycobacterial survival under nitrogen starvation [ 236 ].…”

New perspectives on an ancient pathogen: thoughts for World Tuberculosis Day 2022

“…Davarpanah et al [24] demonstrate reservoirs of a variety of opportunistic environmental mycobacteria in dust and soil in Iranian hospitals as potential sources of infection. Another environmental source of non-TB mycobacteria is water, and the mycobacterial thermophile Mycobacterium hassiacum, although it rarely infects humans, could be used as an indicator of disinfection success with utility in the hospital environment, and also as a source of thermostable and tractable enzymes for drug design [23]. Mycobacteria are used in bioremediation and Ogawa et al [25] investigate the collaborative degradation of phenanthrene by Mycobacteria and Burkholderia.…”

“…There are several papers focused on non-tuberculosis mycobacteria [23][24][25][26]. Davarpanah et al [24] demonstrate reservoirs of a variety of opportunistic environmental mycobacteria in dust and soil in Iranian hospitals as potential sources of infection.…”

Microbial Musings – May 2020

“…Finally, our editor's choice this month, selected by Senior editor Jen Cavet, from Manchester, UK, is a paper from Nuno Empadinhas and colleagues at the University of Ciombra, Portugal, characterizing the growth and survival of an unusual thermophilic Mycobacterium and one of its highly thermostable proteins [12]. Check out the Microbe Post blog for more details.…”