GM and Non-GM Rumen Microbes in Enhancing Animal
Productivity
T. S. Park, J. K. Seo and Jong K. Ha
Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University,
Daehak-dong, Kwanak-gu, Seoul 151-742, Korea
Abstract
Rumen microbes has been extensively used for manipulating the rumen ecology. Genetically modified or non genetic modified are both the type of application for enhancing the ruminal fermentation and improving the performance of ruminants. Construction of genetic modified rumen microbes has been succeeded with adding the various kinds of traits, such as improving fiber digestion, detoxification or reducing methane production in the rumen. This modification strategy mainly targeted into the predominant ruminal bacteria including Butyrivibrio fibrisolvens, Streptococcus bovis and Prevotella ruminicola. However, directly introducing the GM microbes to the rumen ecology is very limited. Recombinant Butyrivibrio fibrisolvens which was transformed with fluoroacetate dehalogenase gene can protect the host animal from plant toxin poisoning. Since the usage of GM microbes has restricted in most countries for its potential risks, many research have been focused on another approach with Non-GM microbes. There are many researches for checking the effect of diverse Non-GM rumen microbes for enhancing the CLA production, mitigation of methane emission, and the possibility as probiotics through in vitro and in vivo. The results show that this alternative use of Non-GM rumen microbes can be an intense candidate for improving the animal productivity through manipulation of rumen ecology. We discussed about how the GM and Non-GM rumen microbes have been used during the last decade and its potential aspects to contribute to the animal productivity.
Keywords: animal productivity, genetic modified, rumen microbes
Introducton
bactera; Butyrivibrio fibrisolvens, Prevotella ruminicola and Streprococcus bovis
whch occupy a large populaton n the rumen and ths fact allows them to be a proper target for genetc manpulaton (Selnger et al., 1996; Eknc et al, 2002). The leadng purposes of genetc manpulaton of predomnant rumen mcrobes are ncreasng the fbrolytc actvty, detoxfcaton, lmtaton of proten degradaton or mprovng mcrobal proten synthess n the rumen (Forano and Flnt., 2000). Although some successful evdences have been reported under n vtro condtons, effcacy of genetcally modfed rumen mcobes has been margnal under n vvo condtons. Usage of non-GM rumen mcrobes can be an alternatve way to avod the potental rsks of GM mcrobes. Some of recent areas of nterest wth non-GM rumen mcrobes are ncreasng the amount of CLA and mtgaton of methane producton. Ths paper wll brefly dscuss potentalty of GM and non-GM rumen mcrobes n enhancng anmal productvty.
Genetcally modfed rumen mcrobes
The prncpal purpose whch genetc modfcaton has been ntended durng several decades s addng the benefcal trats (mprovement of fber dgeston and amno acd synthess, reducton of detary proten degradaton and allevaton of effect of toxc materals) (Gregg et al., 1994; Teather., 1985) nto rumen mcrobes for ther effcent fermentatve acton n the rumen. Ths modfcaton strategy manly targeted nto the predomnant rumnal bactera ncludng B. fibrisolvens, S. bovis and
P. ruminicola (Forano and Flnt., 2000). These efforts resulted n the constructon of varous knds of GM mcrobes.
GM mcrobes often re-ntroduced nto the rumen ecosystem for confrmng the survval rate and capacty to be domnant n ts envronment but the perod of survval was qute restrcted, besdes they usually do not mantan ther recombnantusually do not mantan ther recombnant do not mantan ther recombnant trats (Kobayash and Yamamoto., 2002; Krause et al., 2001). It s beleved that foregn fbrolytc enzyme genes dd not act properly n the rumen ecology. Inhbton by antbacteral-agent, bacterocn, exsted n the natural rumen ecology can beantbacteral-agent, bacterocn, exsted n the natural rumen ecology can be-agent, bacterocn, exsted n the natural rumen ecology can be partly responsble for ths. Despte non-sgnfcant mpact on rumen fermentaton and producton wth GM mcrobes, B. fibrosolvens transformed wth fluoroacetate dehalogenase gene s regarded as one of postve examples (Gregg et al., 1998). Retanng the adequate populaton of recombnant bactera to stablze n the rumen s crucal factor for detoxfcaton. In ths experment GM B. fibrisolvens mantaned ts populaton above 106 cells per ml and ths was enough to detoxfy the toxc
molecule n the rumen ecology.
factors for examnaton of GMO’s rsks Forano and Flnt., 2000). Though the rsks’s rsks Forano and Flnt., 2000). Though the rskss rsks Forano and Flnt., 2000). Though the rsksrsks of GMO are vague, the acceptablty of GMO by the publc who drectly consumevague, the acceptablty of GMO by the publc who drectly consume the anmal products s usually low. Due to the dffculty of publc agreement on certan evaluaton crteron, assessment of GMO’s rsk s not yet fully constructed.assessment of GMO’s rsk s not yet fully constructed. of GMO’s rsk s not yet fully constructed.’s rsk s not yet fully constructed.s rsk s not yet fully constructed. Because the advantage of genetc modfcaton s dstnct and effcent use of ths technology can be benefcal to anmal ndustry, scentfc standard s needed for the proper utlzaton of GMO.
Non-GM rumen mcrobes
on-GM rumen mcrobes
n-GM rumen mcrobes
Snce the usage of GM mcrobes has restrcted n most countres due to therbes has restrcted n most countres due to ther has restrcted n most countres due to therdue to ther therther potental rsks, many research have been focused on another approach wth Non-GM mcrobes. Mcrobes solated from the rumen could be re-ntroduced nto thebes. Mcrobes solated from the rumen could be re-ntroduced nto the. Mcrobes solated from the rumen could be re-ntroduced nto the Mcrobes solated from the rumen could be re-ntroduced nto the dgestve tract of rumnants hopng to enhance dgestve functons.
Major bodes of research results are wth rumen bactera. Isolated rumen bacterum Pseudobutyrivibrio xylanivorans Stran Mz5T was evaluated for ts possble role n the rumen ecology through n vtro studes (ČEPELJNIKet al., 2003). Ths stran produced butyrate as a major product and fber degradng enzymes, and bacterocn were also syntheszed. Characterstcs of ths stran such as provdng enengy to the colonocyte and reducng pathogenc bactera may facltate t as a possble canddate for probotcs. Propionibacteria s also the avalable nomnee for the probotcs. Accordng to the research by Sten et al (2006) ncreased mlk producton and the molar percentage of proponate were detected n dary cows after the treatment of Propionibacteria. Young calves are man targets of probotcs because ths stage s mportant for nfants to develop ther pre-gastrc fermentatveths stage s mportant for nfants to develop ther pre-gastrc fermentatvefermentatveatve organs whch are requred for the effcent degradaton of forage. Dosng probotcare requred for the effcent degradaton of forage. Dosng probotcrequred for the effcent degradaton of forage. Dosng probotcd for the effcent degradaton of forage. Dosng probotc for the effcent degradaton of forage. Dosng probotceffcent degradaton of forage. Dosng probotcdegradaton of forage. Dosng probotc. Dosng probotc mxture compound whch conssted of fve rumen mcrobes ncreased ADG, mproved fbrolytc acton and decreased ncdence of darrhea n young Holstendarrhea n young Holsten n young HolstenHolsten calves (Aldana et al., 2009). Snce dary cows need proper controllng for parturtoncontrollng for parturton for parturton and calvng, probotc supplementaton s n a poston to alter the rumen fermentaton.supplementaton s n a poston to alter the rumen fermentaton. s n a poston to alter the rumen fermentaton.
Megasphaera elsdenii s well-known lactate-utlzng bacterum and Akman et al. (2011) noculated ths bactera nto the rumen for the purpose of reducng rumen acdoss at the postcalvng perod. Though rumnal pH dd not show sgnfcant change, dosng the bacterum resulted n lower acetate : proponate rato and less fluctuaton of rumnal pH and other postve effects on the anmal performance such as mlk producton and energy balance. Smlar postve response to the addton of rumen fung has been reported prevously. Rumen fung secrete varous enzymes to degrade fber components, and some studes tred to use rumen fung as probotcs.
Piromyces sp. solated from goat mproved dgestblty and total VFA producton ndgestblty and total VFA producton n and total VFA producton n vtro, but the same culture dd not show any sgnfcant effect for hefers (Samanta
Interests n CLA whch has benefcal effect on humen health have beenbenefcal effect on humen health have been effect on humen health have been ncreased from the decades upward (Wahle et al., 2004) and extensve research efforts have been made to elucdate the mechansm of CLA formaton n the rumenhave been made to elucdate the mechansm of CLA formaton n the rumen been made to elucdate the mechansm of CLA formaton n the rumen and to fnd ways of enhancng the process. However, only a few studes looked at possblty of usng rumen mcrobes to enhance CLA producton n the rumen. Rumen protozoa are able to synthesze CLA by the somerase actvty though they cannot convert the CLA to others ncludng vaccenc acd and stearc acd (Or-to others ncludng vaccenc acd and stearc acd (Or-Rashd et al., 2008). Among the classfed rumen bactera, Butyrivibrio fibrisolvens
whch s prevalent n the rumen somerlzes lnolec acd at a hgher rate than other rumnal mcrobes (Maa et al., 2007). B. fibrisolvens MDT-5 solated from rumen of goat by Fukuda et al (2006) was used as CLA enhancer n the rumen. The stran was beleved to have hgh lnolec acd somerase actvty and no CLA reductase actvty. By analogy wth ths successful result of MDT-5 whch show ncrement of CLA n pet anmals, there s possblty of obtanng benefcal effects by usng the same stran wth domestc anmals, although t s uncertan wth rumnants whch already have CLA-producng bactera n ther own envronment.
Methane s major green house gas produced by dverse actvtes ncludng agrculture ndustry. Among the agrculture aspect, rumnants take the greataspect, rumnants take the great, rumnants take the great possesson of methane producton through ther enterc fermentaton. Therefore of methane producton through ther enterc fermentaton. Therefore reducng methane emmson by rumnants s emphaszed. Present approaches can be classfed nto largely two strateges. Frst approach s through mprovng the qualty of nutrton suppled to the anmals, so that more product may be produced per unt of methane. Secondly, through the modfcaton of rumen fermentaton usng varous methods actual producton of methane can be reduced n the enterc fermentaton (Iqbal (Iqbal et al., 2008). Homoacetogens are able to utlze H2 comng from fermentaton of feeds n the rumen. Removng hydrogen from the mechansm whch was naturaly used by methanogens to produce methane s benefcal for anmals, because f homoacetogen convert the CO2 to acetate wth hydrogen, the acetate generates energy for the anmal and contrbutes to the anmal productvty.anmal productvty. Lopez et al. (1999) defned the competton ablty of homoacetogen ncubated wth rumnal flud ncludng methanogen n vtro. Wthout any addtves, homoacetogensaddtves, homoacetogens, homoacetogens dd not reduce methane producton, though the amount of methane was reduced after treatment wth 2-bromoethanesulfonc acd. Paul et al. (2011) reported about novel sulphate-reducng bacterum(SRB), Fusobacterium sp, and characterzed ts avalable role n mtgatng methane producton n vtro. Sulphate reducton could be better optons for removng hydrogen from the rumen ecology because these bactera could compete wth methanogens and homoacetogens for utlzaton of H
2.
Acknowledgement
Ths research was supported by Technology Development Program for Agr-culture and Forestry (Project No. 109024032CG000), Mnstry for Food, Agrcul-ture, Forestry and Fsheres, Republc of Korea.
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