| dc.description.abstract | Due to shortage of fossil fuels in Bangladesh, we need to source alternative energy one of
choices may be the lignocellulosic bioethanol production. However the commercial enzymes
for bioethanol production are not available in Bangladesh. Therefore lignocellulase producing
strains is the target of our research.
The study is aimed to characterize a lignocellose degrading strain and to revealing their
mechanism through genome wide investigation. The lignocellulose degrading bacteria was
isolated from Goat rumen contents by screening on the CMC, pectin, xylanand starch
containing agar media. The isolate was named as Klebsiella variicola HSTU-AAM51. The
HSTU-AAM51 showed MR negative, VP negative, catalase positive, oxidase positive, MIU
test negative, citrate negative, TSI, , sucrose, dextrose, lactose, urease and maltose positive in
vitro test. Klebsiella variicola. HSTU- AAM51 was isolated from goat rumen contents and
confirmed to possess xylanase, cellulose and pectinase activity by whole genome sequence
analysis. The complete genome ofKlebsiella vaiicola HSTU- AAM51 strain comprises of
5,564,045 bp in a circular chromosome with a G + C content of 57.2%. Among the predicted
5187 protein-coding genes(CDS), 45 genes are involved in the degradation of lignocellulose
and other polysaccharides, including6cellulose degrading genes (GH3, GH5, GH13, GH94) ,
4xylanose degrading genes (GH10,CE4,GH43), 1 mannose degrading gene (GH5), 4
hemicellulose degrading genes (GH27, GH2, GH13, GH53) , 1 pectin degrading gene (PE1)
and 29 lignin degrading genes. Lignocellulose degrading genes are detected by computational
analysis, where as some CAZy (GH5, GH94, GH10, GH5, CE4, GH53 and PE1) genes
showed signal peptide prediction positive, which proves that they have extracellular enzymes
activity. Finally lignocelluloses degrading enzyme activity was ensured by molecular docking
analysis where ascellulase enzymes (GH3, GH94 and GH5) showed ability to break down
ligand respectively β -D-glucopyranose, alpha & beta –D-Glucose and cellopentaose which
release energy respectively ΔG=-10.51K cal/mol, ΔG=-6.8 K cal/mol and ΔG=-10.3 K
cal/mol. In addition toxylanase enzymes (GH10 and CE4) showed ability to break down
ligand respectivelyβ-D-xylopyranose(XYP),4-O-β -D-xylopyranosyl-β -D-xylopyranose(BXP)
and 2-(N-morpholino)-ethanesulfonic acid(MES), 2-(acetylamino)-2-deoxy-A-Dglucopyranose (NDG) which release energy respectively ΔG=-7.3, -6.3 K cal/mol and ΔG=-
7.3, -6.46 K cal/mol. Moreover hemicellulase enzymes (GH53 and GH13) showed ability to
break down ligand respectively imidazole(IMD),N-acetyl-D-glucoseamine(NAG), β-Dglactose(GAL) and 2-[bis-(2-hydroxy-ethyl)-amino]-2-hydroxymethyl-propane-1,3-diol(BTB)
iii
which release energy respectively ΔG=-9.4, -6.7, -7.0 K cal/mol, ΔG=-7.74 K cal/mol and
pectinase enzymes (PE1) has capability to break down ligand β-D-galactopyranuronic acid
(Pectin) which release energy respectively ΔG=-6.23 K cal/mol. This genome-based analysis
facilitates our understanding of the mechanism underlying the biodegradation of
lignocelluloses. This genome information including CAZyme repertoire will be useful to
understand lingocellulolytic machinery. This study first time reports the whole genome
analysis of Klebsiella variicola HSTU-AAM51 which are enriched with carbohydrate and
lignin degrading useful enzymes for bioethanol production. | en_US |
