Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans

Abstract Background Lignocellulosic biomass is an attractive and sustainable alternative to petroleum-based feedstock for the production of a range of biochemicals, and pretreatment is generally regarded as indispensable for its biorefinery. However, various inhibitors that severely hinder the growt...

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Main Authors: Lihua Zou, Shuiping Ouyang, Yueli Hu, Zhaojuan Zheng, Jia Ouyang
Format: Article
Language:English
Published: BMC 2021-11-01
Series:Biotechnology for Biofuels
Subjects:
Online Access:https://doi.org/10.1186/s13068-021-02078-7
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author Lihua Zou
Shuiping Ouyang
Yueli Hu
Zhaojuan Zheng
Jia Ouyang
author_facet Lihua Zou
Shuiping Ouyang
Yueli Hu
Zhaojuan Zheng
Jia Ouyang
author_sort Lihua Zou
collection DOAJ
description Abstract Background Lignocellulosic biomass is an attractive and sustainable alternative to petroleum-based feedstock for the production of a range of biochemicals, and pretreatment is generally regarded as indispensable for its biorefinery. However, various inhibitors that severely hinder the growth and fermentation of microorganisms are inevitably produced during the pretreatment of lignocellulose. Presently, there are few reports on a single microorganism that can detoxify or tolerate toxic mixtures of pretreated lignocellulose hydrolysate while effectively transforming sugar components into valuable compounds. Alternatively, microbial coculture provides a simpler and more efficacious way to realize this goal by distributing metabolic functions among different specialized strains. Results In this study, a novel synthetic microbial consortium, which is composed of a responsible for detoxification bacterium engineered Pseudomonas putida KT2440 and a lactic acid production specialist Bacillus coagulans NL01, was developed to directly produce lactic acid from highly toxic lignocellulosic hydrolysate. The engineered P. putida with deletion of the sugar metabolism pathway was unable to consume the major fermentable sugars of lignocellulosic hydrolysate but exhibited great tolerance to 10 g/L sodium acetate, 5 g/L levulinic acid, 10 mM furfural and HMF as well as 2 g/L monophenol compound. In addition, the engineered strain rapidly removed diverse inhibitors of real hydrolysate. The degradation rate of organic acids (acetate, levulinic acid) and the conversion rate of furan aldehyde were both 100%, and the removal rate of most monoaromatic compounds remained at approximately 90%. With detoxification using engineered P. putida for 24 h, the 30% (v/v) hydrolysate was fermented to 35.8 g/L lactic acid by B. coagulans with a lactic acid yield of 0.8 g/g total sugars. Compared with that of the single culture of B. coagulans without lactic acid production, the fermentation performance of microbial coculture was significantly improved. Conclusions The microbial coculture system constructed in this study demonstrated the strong potential of the process for the biosynthesis of valuable products from lignocellulosic hydrolysates containing high concentrations of complex inhibitors by specifically recruiting consortia of robust microorganisms with desirable characteristics and also provided a feasible and attractive method for the bioconversion of lignocellulosic biomass to other value-added biochemicals.
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spelling doaj.art-6513628120264b5895f9485d851e4b202022-12-22T00:27:41ZengBMCBiotechnology for Biofuels1754-68342021-11-0114111410.1186/s13068-021-02078-7Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulansLihua Zou0Shuiping Ouyang1Yueli Hu2Zhaojuan Zheng3Jia Ouyang4Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry UniversityJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry UniversityJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry UniversityJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry UniversityJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry UniversityAbstract Background Lignocellulosic biomass is an attractive and sustainable alternative to petroleum-based feedstock for the production of a range of biochemicals, and pretreatment is generally regarded as indispensable for its biorefinery. However, various inhibitors that severely hinder the growth and fermentation of microorganisms are inevitably produced during the pretreatment of lignocellulose. Presently, there are few reports on a single microorganism that can detoxify or tolerate toxic mixtures of pretreated lignocellulose hydrolysate while effectively transforming sugar components into valuable compounds. Alternatively, microbial coculture provides a simpler and more efficacious way to realize this goal by distributing metabolic functions among different specialized strains. Results In this study, a novel synthetic microbial consortium, which is composed of a responsible for detoxification bacterium engineered Pseudomonas putida KT2440 and a lactic acid production specialist Bacillus coagulans NL01, was developed to directly produce lactic acid from highly toxic lignocellulosic hydrolysate. The engineered P. putida with deletion of the sugar metabolism pathway was unable to consume the major fermentable sugars of lignocellulosic hydrolysate but exhibited great tolerance to 10 g/L sodium acetate, 5 g/L levulinic acid, 10 mM furfural and HMF as well as 2 g/L monophenol compound. In addition, the engineered strain rapidly removed diverse inhibitors of real hydrolysate. The degradation rate of organic acids (acetate, levulinic acid) and the conversion rate of furan aldehyde were both 100%, and the removal rate of most monoaromatic compounds remained at approximately 90%. With detoxification using engineered P. putida for 24 h, the 30% (v/v) hydrolysate was fermented to 35.8 g/L lactic acid by B. coagulans with a lactic acid yield of 0.8 g/g total sugars. Compared with that of the single culture of B. coagulans without lactic acid production, the fermentation performance of microbial coculture was significantly improved. Conclusions The microbial coculture system constructed in this study demonstrated the strong potential of the process for the biosynthesis of valuable products from lignocellulosic hydrolysates containing high concentrations of complex inhibitors by specifically recruiting consortia of robust microorganisms with desirable characteristics and also provided a feasible and attractive method for the bioconversion of lignocellulosic biomass to other value-added biochemicals.https://doi.org/10.1186/s13068-021-02078-7Lignocellulosic hydrolysateDetoxificationPseudomonas putidaBacillus coagulansMicrobial consortiumLactic acid
spellingShingle Lihua Zou
Shuiping Ouyang
Yueli Hu
Zhaojuan Zheng
Jia Ouyang
Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
Biotechnology for Biofuels
Lignocellulosic hydrolysate
Detoxification
Pseudomonas putida
Bacillus coagulans
Microbial consortium
Lactic acid
title Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
title_full Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
title_fullStr Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
title_full_unstemmed Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
title_short Efficient lactic acid production from dilute acid-pretreated lignocellulosic biomass by a synthetic consortium of engineered Pseudomonas putida and Bacillus coagulans
title_sort efficient lactic acid production from dilute acid pretreated lignocellulosic biomass by a synthetic consortium of engineered pseudomonas putida and bacillus coagulans
topic Lignocellulosic hydrolysate
Detoxification
Pseudomonas putida
Bacillus coagulans
Microbial consortium
Lactic acid
url https://doi.org/10.1186/s13068-021-02078-7
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