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

Abstract

Lactobacillus plantarum is an attractive candidate for bioprocessing of lignocellulosic biomass due to its high metabolic variability, including its ability to ferment both pentoses and hexoses, as well as its high acid tolerance, a quality often utilized in industrial processes. This bacterium grows naturally on biomass; however, it lacks the inherent ability to deconstruct lignocellulosic substrates. As a first step toward engineering lignocellulose-converting lactobacilli, we have introduced genes coding for a GH6 cellulase and a GH11 xylanase from a highly active cellulolytic bacterium into L. plantarum. For this purpose, we employed the recently developed pSIP vectors for efficient secretion of heterologous proteins. Both enzymes were secreted by L. plantarum at levels estimated at 0.33 nM and 3.3 nM, for the cellulase and xylanase, respectively, in culture at an optical density at 600 nm (OD 600 ) of 1. Transformed cells demonstrated the ability to degrade individually either cellulose or xylan and wheat straw. When mixed together to form a two-strain cell-based consortium secreting both cellulase and xylanase, they exhibited synergistic activity in the overall release of soluble sugar from wheat straw. This result paves the way toward metabolic harnessing of L. plantarum for novel biorefining applications, such as production of ethanol and polylactic acid directly from plant biomass.

Display of recombinant proteins at the surface of lactic acid bacteria: strategies and applications

“…The nisin-based NICE system is a well-known system for inducible expression in L. lactis and several other LAB [32]. A system similar to the NICE system and primarily developed for use in lactobacilli is the pSIP system [38,39] In recent years, this modular vector system for inducible gene expression has been developed for protein secretion and anchoring [21,23,[40][41][42][43][44], exploiting signals from L. plantarum WCFS1.…”

Cloning and Expression of Listeriolysin O in Lactobacillus plantarum

“…This result is compatible with other researchers' findings, that referred to this species as a feasible expression host. 19,26,27 In general, transformation efficiencies in lactobacilli are often lower compared to some other bacteria. Low number or lack of transformants after electroporation may be due to some factors such as various restriction (RM) systems encoded by the host, and dam/dcm methylation pattern of plasmid DNA.…”

Cell surface engineering of industrial microorganisms for biorefining applications

“…Many varieties of surface display systems has been developed for lactic acid bacteria (Hu et al, 2010;Moraïs et al, 2013;Wieczorek et al, 2012;Xu et al, 2011), although we are not aware of reports of the use of such engineered strains for the commercial production of lactic acid or other useful chemicals. One of the major problems for cell surface engineered LAB is that low pH caused by produced lactic acid decreases the activity of displayed cellulase(s) and amylase(s).…”