Butanol Tolerance of Lactiplantibacillus plantarum: A Transcriptome Study.

Kaloyan Petrov,Penka Petrova,Alexander Arsov

doi:10.3390/genes12020181

Kaloyan Petrov, Penka Petrova + Show 1 more

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https://doi.org/10.3390/genes12020181

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Abstract

Biobutanol is a promising alternative fuel with impaired microbial production thanks to its toxicity. Lactiplantibacillus plantarum (L. plantarum) is among the few bacterial species that can naturally tolerate 3% (v/v) butanol. This study aims to identify the genetic factors involved in the butanol stress response of L. plantarum by comparing the differential gene expression in two strains with very different butanol tolerance: the highly resistant Ym1, and the relatively sensitive 8-1. During butanol stress, a total of 319 differentially expressed genes (DEGs) were found in Ym1, and 516 in 8-1. Fifty genes were upregulated and 54 were downregulated in both strains, revealing the common species-specific effects of butanol stress: upregulation of multidrug efflux transporters (SMR, MSF), toxin-antitoxin system, transcriptional regulators (TetR/AcrR, Crp/Fnr, and DeoR/GlpR), Hsp20, and genes involved in polysaccharide biosynthesis. Strong inhibition of the pyrimidine biosynthesis occurred in both strains. However, the strains differed greatly in DEGs responsible for the membrane transport, tryptophan synthesis, glycerol metabolism, tRNAs, and some important transcriptional regulators (Spx, LacI). Uniquely upregulated in the butanol-resistant strain Ym1 were the genes encoding GntR, GroEL, GroES, and foldase PrsA. The phosphoenolpyruvate flux and the phosphotransferase system (PTS) also appear to be major factors in butanol tolerance.

Highlights

In addition to its use as a starting reagent for chemical synthesis in various industries such as medicine and pharmacy, butanol is the most promising alternative fuel to replace today’s gasoline
Transcriptomic methods have revealed the importance for butanol tolerance of efflux pump components, such as those encoded by acrA and acrB in E. coli [16] or srpB in Pseudomonas putida [22], the two-component system encoded by btrTM [23], the master regulator Spo0A in C. acetobutylicum [8], and the nrps3 biosynthetic cluster in C. saccharoperbutylacetonicum N1–4 [24]
The present study aims to reveal the genetic foundations of the natural butanol tolerance of L. plantarum using comparative transcriptomics

Summary

Introduction

In addition to its use as a starting reagent for chemical synthesis in various industries such as medicine and pharmacy, butanol is the most promising alternative fuel to replace today’s gasoline. Butanol emits less unburned hydrocarbon, carbon mono- and dioxide, nitrogen oxides, and other unregulated emissions compared with conventional transport fuels [1] It is preferred over ethanol for the spark-ignition engine because of its higher energy density, excellent combustion characteristics, less corrosiveness, lower vapour pressure and volatility, and the opportunity to be blended with gasoline at any concentration [2]. The effects of butanol on microbial cells include the destruction of the phospholipid bilayer and the membrane lipopolysaccharides [7], inhibition of the cell membrane ATPase activity, and the glucose absorption [8] This is why several genetic approaches have been applied to enhance microbial resistance to butanol; that is, chemical mutagenesis [9,10,11], genomic libraries construction and screening [12,13], forced genomic evolution [14,15], and genome shuffling [16]. Transcriptomic methods have revealed the importance for butanol tolerance of efflux pump components, such as those encoded by acrA and acrB in E. coli [16] or srpB in Pseudomonas putida [22], the two-component system encoded by btrTM [23], the master regulator Spo0A in C. acetobutylicum [8], and the nrps biosynthetic cluster in C. saccharoperbutylacetonicum N1–4 [24]

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