{"title":"Deciphering the lignocellulolytic metabolism and bioethanol production pathway of Klebsiella sp. SWET4 by whole genome and gene expression analyses","authors":"Debapriya Sarkar, Kasturi Poddar, Angana Sarkar","doi":"10.1016/j.biombioe.2024.107212","DOIUrl":null,"url":null,"abstract":"<div><p>The WGS of <em>Klebsiella</em> sp. SWET4 revealed a genome of 5,665,821 bp by assembling 78 scaffolds with N50 and L50 values of 371571 and 5, respectively. BUSCO and ortholog analysis indicated the completeness of the genome and familiarity with <em>Klebsiella variicola</em>. Annotation result confirmed the presence of 5 major cellulose metabolizing genes (<em>bcsZ, bglC, bglA, celA, chbA</em>), besides 4 key xylan degrading genes (<em>xynB, xynT, xylA, xylB</em>) and 4 principal ethanol fermentation (<em>nifJ, adhE, acs, adh1</em>) genes. The lignolytic potential of SWET4 was evident in the kinetic study and the presence of <em>yfeX</em>/<em>efeB</em>, <em>katG</em>, <em>katE</em>, etc. genes were confirmed. Expression study with qPCR indicated overexpression of cellulolytic genes (268.73-fold of <em>bglA</em>, 122.78-fold of <em>bglC</em>, and 45.88-fold of <em>bcsZ</em>) in cellulose broth when compared to glucose. However, less activity was observed for xylanolytic genes (9.19-fold of <em>xylA</em>, 4.29-fold of <em>xylB</em>, and 2.89-fold of <em>xynB</em>) in xylan broth. Additionally, the kinetic study revealed that K<sub>s</sub> was significantly lower for cellulose (7.79 and 0.09 g/L) compared to xylan (193.78 and 3.95 g/L) for primary and secondary growth phases, respectively which confirmed the higher preference of cellulose by SWET4. Further, ethanol estimation by HPLC exhibited an increase in ethanol concentration in banana peel fermentation broth from 0.1 g/L (30 h) to 0.35 g/L (56 h). The <em>adh1</em> gene expression was also found to increase by 84.45-fold, whereas <em>adhE</em> increased by 1.62-fold confirming their influence on ethanol production. This study confirmed the lignocellulolytic and ethanologenic properties of SWET4 enabling the direct biotransformation of cellulosic biomass to ethanol.</p></div>","PeriodicalId":253,"journal":{"name":"Biomass & Bioenergy","volume":null,"pages":null},"PeriodicalIF":5.8000,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biomass & Bioenergy","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S096195342400165X","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"AGRICULTURAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract
The WGS of Klebsiella sp. SWET4 revealed a genome of 5,665,821 bp by assembling 78 scaffolds with N50 and L50 values of 371571 and 5, respectively. BUSCO and ortholog analysis indicated the completeness of the genome and familiarity with Klebsiella variicola. Annotation result confirmed the presence of 5 major cellulose metabolizing genes (bcsZ, bglC, bglA, celA, chbA), besides 4 key xylan degrading genes (xynB, xynT, xylA, xylB) and 4 principal ethanol fermentation (nifJ, adhE, acs, adh1) genes. The lignolytic potential of SWET4 was evident in the kinetic study and the presence of yfeX/efeB, katG, katE, etc. genes were confirmed. Expression study with qPCR indicated overexpression of cellulolytic genes (268.73-fold of bglA, 122.78-fold of bglC, and 45.88-fold of bcsZ) in cellulose broth when compared to glucose. However, less activity was observed for xylanolytic genes (9.19-fold of xylA, 4.29-fold of xylB, and 2.89-fold of xynB) in xylan broth. Additionally, the kinetic study revealed that Ks was significantly lower for cellulose (7.79 and 0.09 g/L) compared to xylan (193.78 and 3.95 g/L) for primary and secondary growth phases, respectively which confirmed the higher preference of cellulose by SWET4. Further, ethanol estimation by HPLC exhibited an increase in ethanol concentration in banana peel fermentation broth from 0.1 g/L (30 h) to 0.35 g/L (56 h). The adh1 gene expression was also found to increase by 84.45-fold, whereas adhE increased by 1.62-fold confirming their influence on ethanol production. This study confirmed the lignocellulolytic and ethanologenic properties of SWET4 enabling the direct biotransformation of cellulosic biomass to ethanol.
期刊介绍:
Biomass & Bioenergy is an international journal publishing original research papers and short communications, review articles and case studies on biological resources, chemical and biological processes, and biomass products for new renewable sources of energy and materials.
The scope of the journal extends to the environmental, management and economic aspects of biomass and bioenergy.
Key areas covered by the journal:
• Biomass: sources, energy crop production processes, genetic improvements, composition. Please note that research on these biomass subjects must be linked directly to bioenergy generation.
• Biological Residues: residues/rests from agricultural production, forestry and plantations (palm, sugar etc), processing industries, and municipal sources (MSW). Papers on the use of biomass residues through innovative processes/technological novelty and/or consideration of feedstock/system sustainability (or unsustainability) are welcomed. However waste treatment processes and pollution control or mitigation which are only tangentially related to bioenergy are not in the scope of the journal, as they are more suited to publications in the environmental arena. Papers that describe conventional waste streams (ie well described in existing literature) that do not empirically address ''new'' added value from the process are not suitable for submission to the journal.
• Bioenergy Processes: fermentations, thermochemical conversions, liquid and gaseous fuels, and petrochemical substitutes
• Bioenergy Utilization: direct combustion, gasification, electricity production, chemical processes, and by-product remediation
• Biomass and the Environment: carbon cycle, the net energy efficiency of bioenergy systems, assessment of sustainability, and biodiversity issues.