title: Enumeration of methanogens with a focus on fluorescence in situ hybridization.
abstract: Methanogens, the members of domain Archaea are potent contributors in global warming. Being confined to the strict anaerobic environment, their direct cultivation as pure culture is quite difficult. Therefore, a range of culture-independent methods have been developed to investigate their numbers, substrate uptake patterns, and identification in complex microbial communities. Unlike other approaches, fluorescence in situ hybridization (FISH) is not only used for faster quantification and accurate identification but also to reveal the physiological properties and spatiotemporal dynamics of methanogens in their natural environment. Aside from the methodological aspects and application of FISH, this review also focuses on culture-dependent and -independent techniques employed in enumerating methanogens along with associated problems. In addition, the combination of FISH with micro-autoradiography that could also be an important tool in investigating the activities of methanogens is also discussed.
authors.affiliation: Dairy Microbiology Division, National Dairy Research Institute, Karnal 132001, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.forename: Sumit Singh
authors.initials: SS
authors.lastname: Dagar
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Mohanty
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Sirohi
authors.forename: Monica
authors.initials: M
authors.lastname: Puniya
authors.forename: Ramesh C
authors.initials: RC
authors.lastname: Kuhad
authors.forename: K P S
authors.initials: KP
authors.lastname: Sangu
authors.forename: Gareth Wyn
authors.initials: GW
authors.lastname: Griffith
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Puniya
mesh_terms: D001105:Archaea / Q000502:physiology*; D017404:In Situ Hybridization, Fluorescence; D008828:Microbiological Techniques / Q000379:methods*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D016914:Ribonuclease H / Q000378:metabolism
chemical_list: D012336:RNA, Ribosomal, 16S; D016914:Ribonuclease H