Expression of fungal cellulase gene in Lactococcus lactis to construct novel recombinant silage inoculants

Abstract

The facultative anaerobic bacterium Lactococcus lactis has been used as a host for expression of a gene isolated from the anaerobic rumen fungus Neocallimastix sp. The coding region of the cellulase gene was obtained from the fungus with the aid of polymerase chain reaction amplification. The gene was then transformed into pCT vector system and the constructed recombinant plasmid was introduced into two L. lactis strains (IL403 and MG1363) by electroporation. The gene encoding the fungal originated cellulase was expressed in both strains successfully although the expression level was relatively lower in comparison with the original enzyme activity. Genetically modified L. lactis strains were used as silage inoculants for pre-biodegradation of the plant biomass during ensiling. That treatment resulted in a notable reduction of the acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of the plant biomass used as silage material. Inoculation with recombinant strain IL1043 resulted in 4.8 and 9.7 % decrease in NDF and ADF contents, respectively while the inoculation of silage with strain MG1363 decreased the ADF content by >5 %.

Effects of bacterial silage inoculants on whole-crop maize silage fermentation and silage digestibility in rams

“…Furthermore, the fibre fractions (ADF and aNDF) of the silage were reduced (P <0.05) with inoculation compared to the control. This supports other studies that reported a reduced fibre content with inoculation (Sanderson, 1993;Keady & Steen, 1994;Ozkose et al, 2009). In contrast, some researchers (Faber et al, 1989;Phillip & Fellner, 1992) did not observe a reduction in cell-wall fractions from inoculated silages compared to the control.…”

“…Our previous research with maize silage (Nkosi et al, 2009) and potato hash silage showed improved aerobic stability of silage with LB inoculation. Contreras-Govea et al (2011) reported a reduced non-protein nitrogen (NPN) concentration in ensiled alfalfa with LL inoculation, and Ozkose et al (2009) reported reduced fibre fractions in ensiled wheat straw with LL inoculation compared to the control. However, the latter studies were conducted under laboratory-scale conditions and the aerobic stability of the silage and the effects of the inoculated silage on animal performance were not determined.…”

Establishment of a Simple Lactobacillus plantarum Cell Consortium for Cellulase-Xylanase Synergistic Interactions

“…A similar result was reported for L. lactis strains transformed with a Neocallimastix sp. cellulase (48). The expression of genes coding for fibrolytic enzymes in lactobacilli is also of interest for the development of …”

Recombinant Cellulase and Cellulosome Systems

“…Similarly, L. lactis was transformed with a cellulase gene from the rumen fungus Neocallimastix sp. [74]. The recombinant L. lactis strain enhanced the digestibility of forage when used in ensiling experiments.…”