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Indian Journal of Microbiology logoLink to Indian Journal of Microbiology
. 2008 Jun 17;48(2):216–227. doi: 10.1007/s12088-008-0027-0

Metagenomics in animal gastrointestinal ecosystem: a microbiological and biotechnological perspective

B Singh 1,, T K Bhat 1, N P Kurade 1, O P Sharma 1
PMCID: PMC3450185  PMID: 23100715

Abstract

Metagenomics- the application of the genomics technologies to nonculturable microbial communities, is coming of age. These approaches can be used for the screening and selection of nonculturable rumen microbiota for assessing their role in gastrointestinal (GI) nutrition, plant material fermentation and the health of the host. The technologies designed to access this wealth of genetic information through environmental nucleic acid extraction have provided a means of overcoming the limitations of culture-dependent microbial genetic exploitation. The molecular procedures and techniques will result in reliable insights into the GI microbial structure and activity of the livestock gut microbes in relation to functional interactions, temporal and spatial relationships among different microbial consortia and dietary ingredients. Future developments and applications of these methods promise to provide the first opportunity to link distribution and identity of rumen microbes in their natural habitats with their genetic potential and in situ activities.

Keywords: Metagenomics, Rumen ecosystem, Gastrointestinal tract microbes, Livestock production

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References

  • 1.Shelswell KJ (2004) http://www.scq.ubc.ca/?p=509
  • 2.Cowan D.A. Microbial genomes-the untapped resource. Trends Biotechnol. 2000;18:14–16. doi: 10.1016/S0167-7799(99)01395-5. [DOI] [PubMed] [Google Scholar]
  • 3.Rappe M.S., Giovannoni S.J. The uncultured microbial majority. Annu Rev Microbiol. 2003;57:369–394. doi: 10.1146/annurev.micro.57.030502.090759. [DOI] [PubMed] [Google Scholar]
  • 4.Stevenson B.S., Eichorst S.A., Wertz J.T., Schmidt T.M., Breznak J.A. New Strategies for cultivation and detection of previously uncultured microbes. Appl Environ Microbiol. 2004;70:4748–4755. doi: 10.1128/AEM.70.8.4748-4755.2004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Handelsman J., Rondon M.R., Brady S.F., Clardy J., Goodman R.M. Molecular biological access to the chemistry of unknown soil microbes: a new frontier for natural products. Chem Biol. 1998;5:R245–R249. doi: 10.1016/S1074-5521(98)90108-9. [DOI] [PubMed] [Google Scholar]
  • 6.Lu J., Santo Domingo J.W., Shanks O.C. Identification of chicken-specific fecal microbial sequences using a metagenomic approach. Water Res. 2007;41:3561–3574. doi: 10.1016/j.watres.2007.05.033. [DOI] [PubMed] [Google Scholar]
  • 7.Shanks O.C., Santo Domingo J.W., Lamendella R., Kelty C.A., Graham J.E. Competeitive metagenomic DNA hybridization identifies host-specific microbial genetic markers in cow fecal samples. Appl Environ Microbiol. 2006;72:4054–4060. doi: 10.1128/AEM.00023-06. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Amann R.L., Ludwig W., Schleifer K.H. Phylogenetic identification and in situ detection of individual microbial cells without cultivation. Microbiol Rev. 1995;59:143–169. doi: 10.1128/mr.59.1.143-169.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 9.Ward N. New directions and interactions in metagenomic research. FEMS Microbiol Ecol Rev. 2006;55:331–338. doi: 10.1111/j.1574-6941.2005.00055.x. [DOI] [PubMed] [Google Scholar]
  • 10.Xu J. Microbial ecology in the age of genomics and metagenomics: concepts, tools, and recent advances. Mol Ecol. 2006;15:1713–1731. doi: 10.1111/j.1365-294X.2006.02882.x. [DOI] [PubMed] [Google Scholar]
  • 11.Cowan D., Meyer Q., Stafford W., Muyanga S., Cameron R., Wittwer P. Metagenomic gene discovery: past, present and future. Trends Biotechnol. 2005;23:321–329. doi: 10.1016/j.tibtech.2005.04.001. [DOI] [PubMed] [Google Scholar]
  • 12.Schloss P.D., Handelsman J. Biotechnological prospects from metagenomics. Curr Opin Biotechnol. 2003;14:303–310. doi: 10.1016/S0958-1669(03)00067-3. [DOI] [PubMed] [Google Scholar]
  • 13.Rees H.C., Grant W.D., Jones B.E., Heaphy S. Diversity of Kenyan soda lake alkaliphiles assessed by molecular methods. Extremophiles. 2004;8:63–71. doi: 10.1007/s00792-003-0361-4. [DOI] [PubMed] [Google Scholar]
  • 14.Hurt R.A., Qiu X., Wu L., Roh Y., Palumbo A.V., Tiedje J.M., Zhou J. Simultaneous recovery of RNA and DNA from soils and sediments. Appl Environ Microbiol. 2001;67:4495–4503. doi: 10.1128/AEM.67.10.4495-4503.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15.Meyer Q.C., Burton S.G., Cowan D.A. Subtractive hybridization magnetic bead capture: a new technique for the recovery of full-length ORFs from the metagenome. Biotechnol J. 2007;2:36–40. doi: 10.1002/biot.200600156. [DOI] [PubMed] [Google Scholar]
  • 16.Zhou J., Bruns M.A., Tiedje J.M. DNA recovery from soils of diverse composition. Appl Environ Microbiol. 1996;62:316–322. doi: 10.1128/aem.62.2.316-322.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Roose-Amsaleg C.L., Garnier-Sillam E., Harry M. Extraction and purification of microbial DNA from soil and sediment samples. Appl Soil Ecol. 2001;18:47–60. doi: 10.1016/S0929-1393(01)00149-4. [DOI] [Google Scholar]
  • 18.Niemi R.M., Heiskanen I., Wallenious K., Lindstrom K. Extraction and purification of DNA in rhizosphere soil samples for PCR-DGGE analysis of bacterial consortia. J Microbiol Methods. 2001;45:155–165. doi: 10.1016/S0167-7012(01)00253-6. [DOI] [PubMed] [Google Scholar]
  • 19.Alm E.W., Zheng D., Raskin L. The presence of humic substances and DNA in RNA extracts affects hybridization results. Appl Environ Microbiol. 2000;66:4547–4554. doi: 10.1128/AEM.66.10.4547-4554.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20.Frischer M.E., Danforth J.M., Newton Healy M.A., Saunders F.M. Whole-cell versus total RNA extraction for analysis of microbial community structure with 16S rRNA-targeted oligonucleotide probes in salt marsh sediments. Appl Environ Microbiol. 2000;66:3037–3043. doi: 10.1128/AEM.66.7.3037-3043.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Griffiths R.I., Whiteley A.S., O’Donnel A.G., Bailey M.J. Rapid method for coextraction of DNA and RNA from natural environments for analysis of ribosomal DNA-and rRNA-based microbial community composition. Appl Environ Microbiol. 2000;66:5488–5491. doi: 10.1128/AEM.66.12.5488-5491.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22.Bohannan B.J., Hughes J. New approaches to analyzing microbial biodiversity data. Review. Curr Opin Microbiol. 2003;6:282–287. doi: 10.1016/S1369-5274(03)00055-9. [DOI] [PubMed] [Google Scholar]
  • 23.Short JM and Mathur EJ (1999) Production and use of normalized DNA libraries. US Patent 6001574
  • 24.Radajewski S., Webster G., Reay D.S., Morris S.A., Ineson P., Nedwell D.B., Prosser J.I., Murrell J.C. Identification of active methylotroph populations in an acidic forest soil by stable-isotope probing. Microbiology. 2002;148:2331–2342. doi: 10.1099/00221287-148-8-2331. [DOI] [PubMed] [Google Scholar]
  • 25.Urbach E.R., Vergin K.L., Giovannoni S.J. Immunochemical detection and isolation of DNA from metabolically active bacteria. Appl Environ Microbiol. 1999;65:1207–1213. doi: 10.1128/aem.65.3.1207-1213.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Bart A., Dankert J., Ende A. Representational difference analysis of Neisseria meningitidis identifies sequences that are specific for the hyper-virulent lineage III clone. FEMS Microbiol Lett. 2000;188:111–114. doi: 10.1111/j.1574-6968.2000.tb09179.x. [DOI] [PubMed] [Google Scholar]
  • 27.Galbraith E.A., Antonopoulos D.A., White B.A. Suppressive subtractive hybridization as a tool for identifying genetic diversity in an environmental metagenome: the rumen as a model. Environ Microbiol. 2004;6:928–937. doi: 10.1111/j.1462-2920.2004.00575.x. [DOI] [PubMed] [Google Scholar]
  • 28.Green C.D., Simons J.F., Taillon B.E., Lewin D.A. Open systems: panoramic views of gene expression. Review J Immunol Methods. 2001;250:67–79. doi: 10.1016/S0022-1759(01)00306-4. [DOI] [PubMed] [Google Scholar]
  • 29.Henckel T., Friedrich M., Conrad R. Molecular analyses of the methane-oxidizing microbial community in rice field soil by targeting the genes of the 16S rRNA, particulate methane monooxygenase, and methanol dehydrogenase. Appl Environ Microbiol. 1999;65:1980–1990. doi: 10.1128/aem.65.5.1980-1990.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Henckel T., Jackel U., Schnell S., Conrad R. Molecular analyses of novel methanotrophic communities in forest soil that oxidize atmospheric methane. Appl Environ Microbiol. 2000;66:1801–1808. doi: 10.1128/AEM.66.5.1801-1808.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.McDonald I.R., Kenna E.M., Murrell J.C. Detection of methanotrophic bacteria in environmental samples with the PCR. Appl Environ Microbiol. 1995;61:116–121. doi: 10.1128/aem.61.1.116-121.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Kobayashi K.S., Chamaillard M., Ogura Y., Henegariu O., Inohara N., Nunez G., Flavell R.A. Nod2-dependent regulation of innate and adaptive immunity in the intestinal tract. Science. 2005;307:731–734. doi: 10.1126/science.1104911. [DOI] [PubMed] [Google Scholar]
  • 33.Clatworthy A.E., Pierson E., Hung D.T. Targeting virulence: a new paradigm for antimicrobial therapy. Review. Nat Chem Biol. 2007;9:541–548. doi: 10.1038/nchembio.2007.24. [DOI] [PubMed] [Google Scholar]
  • 34.Misra R.N., Singla-Pareek S.L., Nair S., Sopory S.K., Reddy M.K. Directional genome walking using PCR. Biotechniques. 2002;33:830–834. doi: 10.2144/02334st07. [DOI] [PubMed] [Google Scholar]
  • 35.Myrick K.V., Gelbart W.M. Universal fast walking for direct and versatile determination of flanking sequence. Gene. 2002;284:125–131. doi: 10.1016/S0378-1119(02)00384-0. [DOI] [PubMed] [Google Scholar]
  • 36.Megonigal M.D., Rappaport E.F., Wilson R.B., Jones D.H., Whitlock J.A., Ortega J.A., Slater D.J., Nowell P.C., Felix C.A. Panhandle PCR for cDNA: a rapid method for isolation of MLL fusion transcripts involving unknown partner genes. Proc Natl Acad Sci USA. 2000;97:9597–9602. doi: 10.1073/pnas.150241797. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 37.Ochman H., Ayala F.J., Hartl D.L. Use of polymerase chain reaction to amplify segments outside boundaries of known sequences. Methods Enzymol. 1993;218:309–321. doi: 10.1016/0076-6879(93)18023-6. [DOI] [PubMed] [Google Scholar]
  • 38.Eschenfeldt W.H., Stols L., Rosenbaum H., Khambatta Z.S., Quaite-Randall E., Wu S., Kilgore D.C., Trent J.D., Donnelly M.I. DNA from uncultured organisms as a source of 2,5-diketo-D-gluconic acid reductases. Appl Environ Microbiol. 2001;67:4206–4214. doi: 10.1128/AEM.67.9.4206-4214.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Rondon M.R., August P.R., Bettrmann A.D., Brady S.F., Grossman T.H., Liles M.R., Loiacono K.A., Lynch B.A., MacNeil I.A., Minor C., Tiong C.L., Gilman M., Osburne M.S., Clardy J., Handelsman J., Goodman R.M. Cloning the soil metagenome: a strategy for accessing the genetic and functional diversity of uncultured microorganisms. Appl Environ Microbiol. 2000;66:2541–2547. doi: 10.1128/AEM.66.6.2541-2547.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Gillespie D.E., Brady S.F., Bettermann A.D., Cianciotto N.P., Liles M.R., Rondon M.R., Clardy J., Goodman R.M., Handelsman J. Isolation of antibiotics turbomycin A and B from a metagenome library of soil microbial DNA. Appl Environ Microbiol. 2002;68:4301–4306. doi: 10.1128/AEM.68.9.4301-4306.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Piel J. A polyketide synthase-peptide synthatase gene cluster from an uncultured bacterial symbiont of Paederus beetle. Proc Natl Acad Sci USA. 2002;99:14002–14007. doi: 10.1073/pnas.222481399. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 42.Diaz-Torres M.L., McNab R., Spratt D.A., Villedieu A., Hunt N., Wilson M., Mullany P. Novel tetracycline resistance determinant from the oral metagenome. Antimicrob Agents Chemother. 2003;47:1430–1432. doi: 10.1128/AAC.47.4.1430-1432.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Henne A., Schimitz R.A., Bomeke M., Gottschalk G., Daniel R. Screening of environmental DNA libraries for the presence of genes conferring lipolytic activity on Escherichia coli. Appl Environ Microbiol. 2000;66:3113–3116. doi: 10.1128/AEM.66.7.3113-3116.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44.Lammle K., Zipper H., Breuer M., Hauer B., Buta C., Brunner H., Rupp S. Identification of novel enzymes with different hydrolytic activities by metagenome expression cloning. J Biotechnol. 2007;127:575–592. doi: 10.1016/j.jbiotec.2006.07.036. [DOI] [PubMed] [Google Scholar]
  • 45.Lan P.T., Sakamoto M., Sakata S., Benno Y. Bacteroides barnesiae sp. nov., Bacteroides salanitronis sp. nov., and Bacteroides gallinarum sp. nov., isolated from chicken caecum. Int J Syst Evol Microbiol. 2006;56:2853–2859. doi: 10.1099/ijs.0.64517-0. [DOI] [PubMed] [Google Scholar]
  • 46.Ferrer M., Beloqui A., Golyshina O.V., Plou F.J., Neef A., Chernikova T.N., Fernandez-Arrojo L., Ghazi I., Ballesteros A., Elborough K., Timmis K.N., Golyshin P.N. Biochemical and structural features of a novel cyclodextrinase from cow rumen metagenome. Biotechnol J. 2007;2:207–213. doi: 10.1002/biot.200600183. [DOI] [PubMed] [Google Scholar]
  • 47.Feng Y., Duan C.J., Pang H., Mo X.C., Wu C.F., Yu Y., Hu Y.L., Wei J., Tang J.L., Feng J.X. Cloning and identification of novel cellulase genes from uncultured microorganisms in rabbit cecum and characterization of the expressed cellulases. Appl Microbiol Biotechnol. 2007;75:319–328. doi: 10.1007/s00253-006-0820-9. [DOI] [PubMed] [Google Scholar]
  • 48.Beloqui A., Pita M., Polaina J., Martinez-Arias A., Golyshina O.V., Zumarraga M., Yakimov M.M., Garcia-Arellano H., Alcalde M., Fernandez V.M., Elborough K., Andreu ,. J., Ballesteros A., Plou F.J., Timmis K.N., Ferrer M., Golyshin P.N. Novel polyphenol oxidase mined from a metagenome expression library of bovine rumen: biochemical properties, structural analysis, and phylogenetic relationships. J Biol Chem. 2006;281:22933–22942. doi: 10.1074/jbc.M600577200. [DOI] [PubMed] [Google Scholar]
  • 49.Gabor E., Liebeton K., Niehaus F., Eck J., Lorenz P. Updating the metagenomics toolbox. Biotechnol J. 2007;2:201–206. doi: 10.1002/biot.200600250. [DOI] [PubMed] [Google Scholar]
  • 50.Beja O., Suzuki M.T., Koonin E.V., Aravind L., Hadd A., Nguyen L.P., Villacorta R., Amjadi M., Garrigues C., Jovanovich S.B., Feldman R.A., DeLong E.F. Construction and analysis of bacterial artificial chromosome libraries from a marine microbial assemblage. Environ Microbiol. 2000;2:516–529. doi: 10.1046/j.1462-2920.2000.00133.x. [DOI] [PubMed] [Google Scholar]
  • 51.Beja O., Aravind L., Koonin E.V., Suzuki M.T., Hadd A., Nguyen L.P., Jovanovich S.B., Gates C.M., Feldman R.A., Spudich J.L., Spudich A.N., DeLong E.F. Bacterial rhodopsin: evidence for a new type of phototrophy in the sea. Science. 2000;289:1902–1906. doi: 10.1126/science.289.5486.1902. [DOI] [PubMed] [Google Scholar]
  • 52.Beja O., Koonin E.V., Aravind L., Taylor L.T., Seitz H., Stein J.L., Bensen D.C., Feldman R.A., Swanson R.V., DeLong E.F. Comparative genomic analysis of archaeal genotypic variants in a single population and in two different oceanic provinces. Appl Environ Microbiol. 2002;68:335.345. doi: 10.1128/AEM.68.1.335-345.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53.Quaiser A., Ochsenreiter T., Klenk H.P., Kletzin A., Treusch A.H., Meurer G., Eck J., Sensen C.W., Schelper C. First insight into the genome of an uncultivated crenarchaeote from soil. Environ Microbiol. 2002;4:603–611. doi: 10.1046/j.1462-2920.2002.00345.x. [DOI] [PubMed] [Google Scholar]
  • 54.Liles M.R., Manske B.F., Bintrim S.B., Handelsman J., Goodman R.M. A census of rRNA genes and linked genomic sequences within a soil metagenomic library. Appl Envron Microbiol. 2003;69:2684–2691. doi: 10.1128/AEM.69.5.2684-2691.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 55.Huson D.H., Auch A.F., Qi J., Schuster S.C. MEGAN analysis of metagenomic data. Genome Res. 2007;17:377.386. doi: 10.1101/gr.5969107. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 56.Jones B.V., Marchesi J.R. Transposon-aided capture (TRACA) of plasmids resident in the human gut mobile metagenome. Nature Methods. 2007;4:55–61. doi: 10.1038/nmeth964. [DOI] [PubMed] [Google Scholar]
  • 57.Savage D.C. Microbial ecology of gastrointestinal tract. Annu Rev Microbiol. 1977;31:107–133. doi: 10.1146/annurev.mi.31.100177.000543. [DOI] [PubMed] [Google Scholar]
  • 58.O’Hara A.M., Shanahan F. Gut microbiota: mining for therapeutic potential. Clin Gastrointerol Hepatol. 2007;5:274–284. doi: 10.1016/j.cgh.2006.12.009. [DOI] [PubMed] [Google Scholar]
  • 59.Goodacre R. Metabolomics of a superorganism. J Nutr. 2007;137(Suppl1):259S–266S. doi: 10.1093/jn/137.1.259S. [DOI] [PubMed] [Google Scholar]
  • 60.Lorenz P., Eck J. Metagenomics and industrial applications. Nat Rev Microbiol. 2005;3:510–516. doi: 10.1038/nrmicro1161. [DOI] [PubMed] [Google Scholar]
  • 61.Walter J., Mangold M., Tannock G.W. Construction, analysis, and β-glucanase screening of a bacterial artificial chromosome library from the large-bowel microbiota of mice. Appl Environ Microbiol. 2005;71:2347–2354. doi: 10.1128/AEM.71.5.2347-2354.2005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 62.Eckburg P.B., Bik E.M., Bernstein C.N., Purdom E., Dethlefsen L., Sargent M., Gill S.R., Nelson K.E., Relman D.A. Diversity of the human intestinal microbial flora. Science. 2005;308:1635–1638. doi: 10.1126/science.1110591. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 63.Beriberi M., Hewson I., Felts B., Mahaffy J.M., Nulton J., Salamon P., Rohwer F. Metagenomics of uncultured viral community from human feces. J Bacteriol. 2003;185:6220–6223. doi: 10.1128/JB.185.20.6220-6223.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 64.Selinger L.B., Forsberg C.W., Cheng K.J. The rumen: a unique source of enzymes for enhancing livestock production. Anaerobe. 1996;2:263–284. doi: 10.1006/anae.1996.0036. [DOI] [PubMed] [Google Scholar]
  • 65.Singh B., Bhat T.K., Singh B. Exploiting gastrointestinal microbes for livestock and industrial development. Asian-Aust J Anim Sci. 2001;14:567–586. [Google Scholar]
  • 66.Palackal N., Lyon C.S., Zaidi S., Luginbuhl P., Dupree P., Goubet F., Macomber J.L., Short J.M., Hazlwood G.P., Robertson D.E., Steer B.A. A multifunctional hybrid glycosyl hydrolase discovered in an uncultured microbial consortium from ruminant gut. Appl Micobiol Biotechnol. 2007;74:113–124. doi: 10.1007/s00253-006-0645-6. [DOI] [PubMed] [Google Scholar]
  • 67.Leser T.D., Amenuvor J.Z., Jensen T.K., Lindecrona R.H., Boye M., Møller K. Culture-independent analysis of gut bacteria: the pig gastrointestinal tract microbiota revisited. Appl Environ Microbiol. 2002;68:673–690. doi: 10.1128/AEM.68.2.673-690.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 68.Stevenson D.M., Weimer P.J. Dominance of Prevotella and low abundance of classical ruminal bacterial species in the bovine rumen revealed by relative quantification real-time PCR. Appl Microbiol Biotechnol. 2007;75:165–174. doi: 10.1007/s00253-006-0802-y. [DOI] [PubMed] [Google Scholar]
  • 69.Shinkai T., Kobayashi Y. Localization of ruminal cellulolytic bacteria on plant fibrous materials as determined by fluorescence in situ hybridization and real-time PCR. Appl Environ Microbiol. 2007;73:1646–1652. doi: 10.1128/AEM.01896-06. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 70.Ferrer M., Golyshina O.V., Chernikova T., Khachane A.N., Reyes-Durate D., Santos V.A., Strompl C., Elborough K., Jarvis G., Neef A.N., Yakimov M.M., Timmis K.N., Golyshin P.N. Novel hydolase diversity retrieved from a metagenome library of bovine rumen microflora. Environ Microbiol. 2005;7:1996–2010. doi: 10.1111/j.1462-2920.2005.00920.x. [DOI] [PubMed] [Google Scholar]
  • 71.Skillman L.C., Toovey A.F., Williams A.J., Wright A.G. Development and validation of a real-time PCR method to quantify rumen protozoa and examination and validity between Entodinium populations in sheep offered a hay-based diet. Appl Environ Microbiol. 2006;72:200–206. doi: 10.1128/AEM.72.1.200-206.2006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 72.Nelson K.E., Zinder S.H., Hance I., Burr P., Odongo D., Wasawo D., Odenyo A., Bishop R. Phylogenetic analysis of the microbial populations in the wild herbivore gastrointestinal tract: insight into an unexplored niche. Environ Microbiol. 2003;5:1212–1220. doi: 10.1046/j.1462-2920.2003.00526.x. [DOI] [PubMed] [Google Scholar]
  • 73.Firkins J.L., Yu Z., Morrison M. Ruminal nitrogen metabolism: perspectives for integration of microbiology and nutrition for dairy. J Dairy Sci. 2007;90(Suppl1):E1–E16. doi: 10.3168/jds.2006-518. [DOI] [PubMed] [Google Scholar]
  • 74.Nicholson M.J., Evans P.N., Joblin K.N. Analysis of metahnogens diversity in the rumen using temporal temperature gradient gel electrophoresis: identification of uncultured methanogens. Microb Ecol. 2007;54:141–150. doi: 10.1007/s00248-006-9182-1. [DOI] [PubMed] [Google Scholar]
  • 75.Chen R., LaPara T.M. Aerobic biological treatment of low-strength synthetic wastewater in membrane-coupled bioreactors: the structure and function of bacterial enrichment cultures as the net growth rate approaches zero. Microb Ecol. 2006;51:99–108. doi: 10.1007/s00248-005-0081-7. [DOI] [PubMed] [Google Scholar]
  • 76.Akselband Y., Cabral C., Castor T.P., Chikarmane H.M., McGrath P. Enrichment of slow-growing marine microorganisms from mixed cultures using gel microdrop (GMD) growth assay and fluorescent-activated cell sorting. J Exp Marine Biol Ecol. 2006;329:196–205. doi: 10.1016/j.jembe.2005.08.018. [DOI] [Google Scholar]
  • 77.Kruger M., Wolters H., Gehre M., Joye S.B., Richnow H.H. Tracking the slow growth of methane-oxidizing communities by (15)N-labeling techniques. FEMS Microbiol Ecol. 2008;63:401–411. doi: 10.1111/j.1574-6941.2007.00431.x. [DOI] [PubMed] [Google Scholar]
  • 78.Denman S.E., McSweeney C.S. Development of a real-time PCR assay for monitoring anaerobic fungal and cellulolytic bacterial populations within the rumen. FEMS Microbiol Ecol. 2006;58:572–582. doi: 10.1111/j.1574-6941.2006.00190.x. [DOI] [PubMed] [Google Scholar]
  • 79.Mosoni P., Chaucheyras-Durand F., Bera-Mailllet C., Forono E. Quantification by real-time PCR of cellulolytic bacteria in the rumen of sheep after supplementation of a forage diet with readily fermentable carbohydrates: effect of a yeast additive. J Appl Microbiol. 2007;103:2676–2685. doi: 10.1111/j.1365-2672.2007.03517.x. [DOI] [PubMed] [Google Scholar]
  • 80.Schmeisser C., Steele H., Streit W.R. Metagenomics, biotechnology with non-culturable microbes. Appl Microbiol Biotechnol. 2007;75:955–962. doi: 10.1007/s00253-007-0945-5. [DOI] [PubMed] [Google Scholar]
  • 81.Kowalchuk G.A., Speksnijder A.G.C., Zhang K., Goodman R.M., Veen J.A. Finding the needles in metagenome haystack. Microbial Ecol. 2007;53:475–485. doi: 10.1007/s00248-006-9201-2. [DOI] [PMC free article] [PubMed] [Google Scholar]

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