Pectinase is one of the important enzymes of industrial sectors. Presently, most of the pectinases are of plant origin but there are only a few reports on bacterial pectinases. The aim of the present study was to isolate a novel and potential pectinase producing bacterium as well as optimization of its various parameters for maximum enzyme production. A total of forty bacterial isolates were isolated from vegetable dump waste soil using standard plate count methods. Primary screening was done by hydrolysis of pectin. Pectinase activity was determined by measuring the increase in reducing sugar formed by the enzymatic hydrolysis of pectin. Among the bacterial isolates, the isolate K6 exhibited higher pectinase activity in broth medium and was selected for further studies. The selected bacterial isolate K6 was identified as Chryseobacterium indologenes strain SD. The isolate was found to produce maximum pectinase at 37°C with pH 7.5 upon incubation for 72 hours, while cultured in production medium containing citrus pectin and yeast extract as C and N sources, respectively. During enzyme-substrate reaction phase, the enzyme exhibited its best activity at pH of 8.0 and temperature of 40°C using citrus pectin as substrate. The pectinase of the isolate showed potentiality on different types of fruit juice clarification.
The abundant macrophage population of the intestinal lamina propria turns over rapidly and is replaced by blood monocytes. The differentiation and survival of resident intestinal macrophages depends upon signals from the macrophage colony-stimulating factor receptor (CSF1R). The response of human monocyte-derived macrophages (MDM) grown in macrophage colony-stimulating factor (CSF1) to bacterial lipopolysaccharide (LPS) has been proposed as a model for the differentiation and adaptation of monocytes entering the intestinal lamina propria. We hypothesized that dysregulation of this response leads to susceptibility to chronic inflammatory bowel disease (IBD). To address this hypothesis we analyzed transcriptomic variation in MDM from affected and unaffected sib pairs/trios from 22 IBD families and 6 healthy controls. There was no overall or inter-sib distinction between affected and unaffected individuals in basal gene expression or the stereotypical time course of the response to LPS. However, the basal or LPS-inducible expression of individual genes including inflammatory cytokines and many associated with IBD susceptibility in genome-wide association studies (GWAS) varied by as much as 100-fold between subjects. Extreme independent variation in the expression of pairs of HLA-associated transcripts (HLA-B/C, HLA-A/F and HLA-DRB1/DRB5) was associated with HLA genotype providing a novel explanation for the HLA association with disease susceptibility. The relationship between single nucleotide variant (SNV) genotype and gene expression at other loci was weaker and inconsistent suggesting that much of the variation arises from the integration of multiple trans-acting effects. For example, expression of IL1B at 2 hrs of LPS treatment was significantly associated with local SNV genotype and with peak expression of IL23A at 7 hrs. By contrast, there was no evidence of association between peak IL6 mRNA at 7hrs, IL6-associated SNV genotype or IL1B at 2 hrs. Our results support the view that gene-specific dysregulation in macrophage adaptation to the intestinal milieu provides a plausible explanation for genetic susceptibility to IBD. The analysis also suggests that the molecular basis of susceptibility is unique to each individual which may contribution to variation in the precise environmental trigger, the consequent pathology and response to treatment.
Escherichia coli
(
E. coli
) is an important commensal in the human gut; however, it is unknown whether strains show site-specificity in the lower gut. To investigate this, we assessed genotypic and phenotypic differences in 37 clone pairs (two strains with very similar multiple locus variable-number-tandem-repeat analysis [MLVA] profiles) of
E. coli
isolated from mucosal biopsies of two different gut locations (terminal ileum and rectum). The clone pairs varied at the genomic level; single nucleotide polymorphisms (SNPs) were common, multiple nucleotide polymorphisms (MNPs) were observed but less common, and few indels (insertions and deletions) were detected. The variation was higher in clone pairs that are associated with non-human-associated sequence types (ST) compared to human-associated STs, such as ST95, ST131, and ST73. No gene(s) with non-synonymous mutations were found to be commonly associated with either the terminal ileum or the rectal strains. At the phenotypic level, we identified the metabolic signatures for some STs. Rectum strains of some STs showed consistently higher metabolic activity with particular carbon sources. Clone pairs belonging to specific STs showed distinct growth patterns under different pH conditions. Overall, this study showed that
E
.
coli
may exhibit genomic and phenotypic variability at different locations in the gut. Although genomics did not reveal significant information suggesting the site-specificity of strains, some phenotypic studies have suggested that strains may display site-specificity in the lower gut. These results provide insights into the nature and adaptation of
E. coli
in the lower gut of humans. To the best of our knowledge, no study has investigated or demonstrated the site-specificity of commensal
E. coli
in the human gut.
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