Antimicrobial production by strictly anaerobic Clostridium spp

Antimicrobial resistance continues to rise on a global scale, affecting the environment, humans, animals and food systems. Use of natural antimicrobials has been favoured over synthetic molecules in food preservation owing to concerns over the adverse health effects of synthetic chemicals. The continuing need for novel natural antimicrobial compounds has spurred research to investigate natural sources, such as bacteria, for antimicrobials. The antimicrobial-producing potential of bacteria has been investigated in numerous studies. However, the discovery of antimicrobials has been biased towards aerobes and facultative anaerobes, and strict anaerobes such as Clostridium spp. have been largely neglected. In recent years, genomic studies have indicated the genetic potential of strict anaerobes to produce putative bioactive molecules and this has encouraged the exploration of Clostridium spp. for their antimicrobial production. So far, only a limited number of antimicrobial compounds have been isolated, identified and characterised from the genus Clostridium. This review discusses our current knowledge and understanding of clostridial antimicrobial compounds as well as recent genome mining studies of Clostridium spp. focused at identification of putative gene clusters encoding bacterial secondary metabolite groups and peptides reported to possess antimicrobial properties. Furthermore, opportunities and challenges in the identification of antimicrobials from Clostridium spp. using genomic-guided approaches are discussed. The limited studies conducted so far have identified the genus Clostridium as a viable source of antimicrobial compounds for future investigations.