Expression of a modified Neocallimastix patriciarum xylanase in Butyrivibrio fibrisolvens digests more fibre but cannot effectively compete with highly fibrolytic bacteria in the rumen

Abstract

Aims: This study investigated the competitive abilities of two Neocallimastix patriciarum‐derived xylanases constructs in Butyrivibrio fibrisolvens H17c (xynA and pUMSX) and their ability to compete in vivo. Methods and Results: The digestibility of neutral detergent fibre (NDF) increased during co‐culture of xynA or pUMSX and weakly cellulolytic, but not with highly cellulolytic, ruminococci. Competition studies among xynA, pUMSX and cellulolytic consortia demonstrated that xynA was the fittest. XynA did not persist at high levels in the rumen and was undetectable after 22 days. Conclusions: The construction of recombinant xylanolytic B. fibrisolvens does improve the digestibility of fibre above that of the native, but digestibility is still less than that of the most potent fibre digesters such as ruminococci. Significance and Impact of the Study: Fibre digestion may be improved by genetic manipulation of ruminal bacteria but ecological parameters, such as persistence in vivo and the niche of the organism, must be taken into account.

Biochanin A improves fibre fermentation by cellulolytic bacteria

“…Strategies for improving cellulose hydrolysis and consequent energy conversion have been extensively explored, including those targeting both substrate modification (e.g., mechanical and chemical pretreatments, genetic manipulation) and genetic and ecological manipulation of the rumen cellulolytic guild (e.g., inoculation; Krause et al 2003). Whereas the development of technologies for modifying fibrous substrates to enhance ruminal fibre digestibility has been successful (Burroughs et al 1960;Wilkins and Minson 1970;Laredo and Minson 1975;Agosin and Odier 1985;Cherney et al 1991;Hu et al 1991), attempts at manipulation of the cellulolytic guild itself have so far been unsuccessful (Hungate 1966;Varel et al 1995;Krause et al 1999Krause et al , 2001aKrause et al , 2001bDehority and Tirabasso 2000). Therefore, strategies for improving cellulolytic fermentative efficiency by ecological manipulation of the cellulolytic guild are of interest.…”

Factors that limit maintenance of recombinant rumen bacterium in sheep rumen

“…More understanding in the rumen microbial ecosystem is undoubtedly necessary for the application of recombinant rumen bacteria. Poor competing ability of a recombinant B. fibrisolvens against indigenous fibrolytic bacteria in the rumen has been documented in the recent publication (Krause et al. 2001).…”

“…More understanding in the rumen microbial ecosystem is undoubtedly necessary for the application of recombinant rumen bacteria. Poor competing ability of a recombinant B. fibrisolvens against indigenous fibrolytic bacteria in the rumen has been documented in the recent publication (Krause et al 2001). The details of the mechanism involved in the establishment and shift of a complex ecosystem are being explored at molecular level (Whitford et al 1998;Tajima et al 2001), which may provide a clue for solving the problems that we encounter for the use of recombinant rumen bacteria.…”

Recent Topics in Rumen Microbiology with Particular Reference to Animal Production in Japan

“…The basic strategy has been to enhance the cellulolytic and hemicellulolytic activity. Many genes encoding fibrolytic enzymes have been cloned and characterized from ruminal microbes and several research institutes have produced highly fibrolytic microbes 12,15,29,37) . Regulation of the gene expression of fibrolytic enzymes has been partially determined in Prevotella 24) .…”