Abstract
Jute, an important cash crop in Bangladesh, is used for many purposes. But water crisis and
deterioration of water quality during jute retting process are the major problems. The present
study was undertaken during 2016-2018 to select and characterize efficient jute retting bacterial
strains for reducing jute- retting period and to improve fibre quality. Water and soil samples
were collected from major jute growing areas of Bangladesh. Total 120 bacterial strains were
isolated from water and soil samples following pour plate and spread plate methods and
purified by sub-cultured methods based on well isolated colony morphology. From them, 35
pectinolytic bacterial strains viz., Si, S2., S3, S4, S5, S6, S7, Sg, S9, S10, S11, S12 S13, S14 S15, S16, S18a S19,
S20, S21, S22, S23, S24, S25, S26, S27b, S28, S29, S33b, S35, S37, S38, S39, S40, and S41 were screened out based on
their pectin degrading ability. The enzyme (polygalacturonase, pectin lyase, xylanase and
cellulase) activities of the 35 individual strains were recorded and 19 bacterial consortia viz., C,
C2, C3, C4, C5, C6, C7, Cs, C9, C10, C11, C12 C13, C14, C15, C16, C17, C18, and C19 were prepared in
different combinations based on qualitative and quantitative enzyme activities of individual
bacterial strains. The enzyme activities of the bacterial consortia were higher than the individual
strains and, thereby, bacterial consortia were used in the jute retting experiments. The
morphological (colony form, elevation, margin, colour and texture), physical (motility test),
biochemical (Gram staining, catalase test, oxidase test, citrate utilization test, indole production
test, urease test, nitrate reduction test, MR test, VP test, and sugar fermentation test) and
molecular (Genomic DNA isolation from 35 strains, DNA amplification by PCR with ERIC
primers, DNA fingerprinting, 165 rRNA gene amplification of 15 bacterial strains, PCR product
purification, purified DNA sequencing, identification of 15 bacterial strains using BLASTn search
and phylogenetic analysis at genus/species level) characters of the bacterial strains were studied.
A dendrogram was constructed by employing UPGMA method based on morpho-physiological
characters of 35 strains. Another dendrogram was also formed based on ERIC-PCR fingerprint
data following the same method. In accordance with ERIC-PCR fingerprint based UPGMA
dendrogram, 15 bacterial strains viz., S4, S6, S7, S9, S12, S13, S16, S19, S22, S24, S28, S29, S33b, S40 and S41
were selected and 16S rRNA genes were sequenced. Through BLASTn search, 15 bacterial strains
were identified at species level of which 6 strains viz., Bacillus cereus (S4, S6, S12, S24, S29), and
Bacillus subtilis (S41) were previously reported as jute retting bacteria. The other identified 9
species viz., Bacillus tropicus (S9, S22), Priestia aryabhattai (S336), Bacillus aerius (S13), Aeromonas
sanarellii (S16), Enterobacter hormaechei (S2s), Enterobacter ludwigii (S), Citrobacter freundii (S19) and
Shigella flexneri (S40) were not reported earlier as jute retting bacteria. Based on phylogenetic
analysis, bacterial strains belonged to two predominant phyla-Firmicutes (~71.43%) and
Proteobacteria (~28.57%). Nine out of the phylogenetically identified 15 bacterial strains viz.,
Bacillus cereus (S4, S6, S12, S24, S29), Bacillus subtilis (S41), Bacillus aryabhattai (S33t), Bacillus pumilus
(S13) and Escherichia coli (S40) were previously reported as jute retting bacteria. The other
identified 6 species viz., Bacillus tropicus (S9, S22), Enterobacter cloacae (S2s), Enterobacter sp. (S7),
Aeromonas sp. (S16) and one unknown bacterium (S19) were not reported before as jute retting
bacteria by any scientist. In both the cases, the genus Bacillus was dominant. Inoculation with
bacterial consortia demonstrated a significant reduction in jute retting period both under field
(10.00 to 13.33 days against 16.67 days in control) and lab (11.33 to 15.33 days against 27.33 days
in control) conditions with remarkable improvement in fibre quality. The consortia C19 and C18
performed better in reducing jute retting period and improving fibre quality compared to other
consortia. Therefore, the farmers can use bacterial consortia C19 or C18 for reducing jute retting
period and obtaining good quality jute fibre.