Introducing transglutaminase with its precursor region into Clostridium acetobutylicum improves its tolerance to oxidative stress and solvent production

We developed a new strategy to improve the aero-tolerance of Clostridium acetobutylicum, an obligate anaerobic bacterium widely used in solvent (acetone-butanol-ethanol) production. The gene mtg which encodes microbial transglutaminase mature protein and its precursor region (pro) were cloned from Streptomyces mobaraensis. Subsequently, the pro-mtg was introduced into Clostridium acetobutylicum under the anhydrotetracycline inducible promoter Pcm-2tetO1 that we previously developed. Transglutaminase has been reported to be involved in oxidative stress in many human diseases. Here we found that the introduction of pro-mtg into Clostridium acetobutylicum resulted in a significantly enhanced survival upon aeration and hydrogen peroxide challenges, as compared with the control. Penicillin susceptibility test indicated that the cross-linking activity of MTG might alter cell wall architecture and then improve the cellular resistance to oxidative stress. In addition, increased biomass concentration, reduced production of butyrate, as well as increased production of solvents by the recombinant Clostridium acetobutylicum strain with pro-mtg, were also observed. Together with our previous observation that MTG improves the growth performance of Lactococcus lactis under aerobic conditions, introduction of MTG into non-MTG-producing microorganisms thus can be considered as a useful approach to improve the physiological functionality of the host microorganisms. (C) 2014 Elsevier Ltd. All rights reserved.