Abstract
Gelling agents are required for formulating both solid and semisolid media, vital for the isolation of microorganisms. Gelatin was the first gelling agent to be discovered but it soon paved the way for agar, which has far superior material qualities. Source depletion, issues with polymerase-chain-reaction and inability to sustain extermophiles etc., necessitate the need of other gelling agents. Many new gelling agents, such as xantham gum, gellan gum, carrageenan, isubgol, and guar gum have been formulated, raising the hopes for the growth of previously unculturable microorganisms. We evaluate the progress in the development of gelling agents, with the hope that our synthesis would help accelerate research in the field.
Highlights
Gelling agents are added to the liquid microbial media to convert them into semi-solid or solid media
Its digestion by bacteria and melting temperature at 37◦C limited its use. These problems associated with gelatin propelled the search for alternative agents
The media produced with food grade agar have less clarity than that produced with bacteriological agar (Kang et al, 1982; Petrovski and Tillett, 2012)
Summary
Gelling agents are added to the liquid microbial media to convert them into semi-solid or solid media. Some colloidal polysaccharides and certain proteins of microbial and plant origin act as solidifiers or stabilizers in the medium by forming continuous three-dimensional molecular network. Diffusion rate is dependent on the viscosity of the medium, which subsequently depends on the concentration and physicochemical characteristics of the agent (Ackers and Steere, 1962; Palaniraj and Jayaraman, 2011). Several mesophiles and extremophiles are currently unculturable or poorly culturable due to the lack of proper biotic and abiotic factors. Traditional sources of gelling agents are being overused, further necessitating the need of new gelling agents. Recent work on gelling agents that can withstand variety of temperatures and pressures have helped in culturing newer microbes, including few extremophiles, which could otherwise not be grown (Becker et al, 1998; Jain et al, 2005). We attempt to fill that lacuna by covering gelling agents, which support the growth of mesophiles and agents, which support the growth of extremophiles
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
