Gelling and reducing agents are potential carbon and energy sources in culturing of anaerobic microorganisms

Most microbial species inhabiting natural environments have not been isolated in pure cultures using conventional media and laboratory conditions, but the reason behind this is unclear. Here, we provided a new explanation for the phenomenon, in that both the gelling agents, like agar and gellan gum, and reducing agent L-cysteine-HCl in the media provide extra carbon and energy sources to microorganisms and therefore decrease the chance in isolation specifically for the supplemented substrate which is supposed to be the sole source of carbon and energy. This result demonstrated that further improvement in the effectiveness of isolation of targeted microorganisms will be facilitated by subtracting the overlooked organic ingredients in the medium and more innovations.