Screening of lactic acid bacteria for their potential as microbial cell factories for bioconversion of lignocellulosic feedstocks

Abstract

BackgroundThe use of fossil carbon sources for fuels and petrochemicals has serious impacts on our environment and is unable to meet the demand in the future. A promising and sustainable alternative is to substitute fossil carbon sources with microbial cell factories converting lignocellulosic biomass into desirable value added products. However, such bioprocesses require availability of suitable and efficient microbial biocatalysts, capable of utilizing C5 sugars and tolerant to inhibitory compounds generated during pretreatment of biomass. In this study, the performance of a collection of lactic acid bacteria was evaluated regarding their properties with respect to the conversion of lignocellulosic feedstocks. The strains were examined for their ability to utilize xylose and arabinose as well as their resistance towards common inhibitors from pretreated lignocellulosic biomass (furan derivatives, phenolic compounds, weak acids).ResultsAmong 296 tested Lactobacillus and Pediococcus strains, 3 L. pentosus, 1 P. acidilactici and 1 P. pentosaceus isolates were found to be both capable of utilizing xylose and arabinose and highly resistant to the key inhibitors from chemically pretreated lignocellulosic biomass. When tested in broth with commonly found combinations of inhibitors, the selected strains showed merely 4%, 1% and 37% drop in growth rates for sugarcane bagasse, wheat straw and soft wood representatives, respectively, as compared to Escherichia coli MG1655 showing decreased growth rates by 36%, 21% and 90%, respectively, under the same conditions.ConclusionThe study showed that some strains of Lactobacilli and Pediococci have the potential to be used as production platforms for value-added products from pretreated lignocellulosic biomass. Selected Lactobacilli and Pediococci strains were able to tolerate the key inhibitors in higher concentrations compared to E.coli; in addition, as these isolates were also capable of fermenting xylose and arabinose, they constitute good candidates for efficient lignocellulosic feedstock bioconversions.

Bacterial biodegradation and bioconversion of industrial lignocellulosic streams

“…Application of these strains for biological treatment would require modifications to increase resistance against inhibitors. Boguta et al (2014) isolated lactic acid bacteria with high resistance toward furfuryl alcohol, vanillin, and vanillin alcohol.…”

“…Lactic acid bacteria are commonly used in the food industry for the production of dairy products and are characterized by their ability to grow at low pH. Boguta et al (2014) screened lactic acid bacteria for their potential use in pretreatment of lignocellulosic feedstocks. Application of these strains for biological treatment would require modifications to increase resistance against inhibitors.…”

Whey-derived valuable products obtained by microbial fermentation

“…The increasing demand for gasoline and the depletion of fossil fuels as well as security and environmental concerns are the main reasons for the great amount of research seeking for alternative energy resources (Boguta et al 2014;Raman and Gnansounou 2014). Validation of carbon credits and assurance of economic and political security are issues that are necessary to evaluate for the development of alternative biofuels.…”

Agricultural Residues as Feedstocks for Lactic Acid Fermentation

“…Lupines can contain more than 71 % (w/w) hemicellulose, while residues from grain production contain around 30 % (w/w) ( Table 1). Pentose and hexose sugars in hemicellulose are potential carbon sources, however, not all lactic acid producing microbial strains grow on these sugars and produce lactic acid at a high yield (14)(15)(16).…”