The use of microbial enzymes is highly encouraged in paper and pulp industries to reduce the excessive use of hazardous chemicals. During the study, xylanase of Bacillus stratosphericus EB-11 was characterized for pulp bleaching applications. The extracellular xylanase was produced under submerged fermentation using bamboo waste as a natural carbon source. There was fast cell division and enzyme production under optimized fermentation conditions in the bioreactor. The highest activity was 91,200U after 30 h of growth with Km and Vmax of 3.52 mg/mL and 391.5 μmol/min per mg respectively. The purified enzyme with molecular mass ~ 60 kDa had conferred positive activity on native PAGE. The strong inhibition by ethylenediaminetetraacetate and SDS showed the metallo-xylanase nature of the purified enzyme. The bacterial xylanase reduces the use of hydrogen peroxide by 0.4%. Similarly, biological oxygen demand and chemical oxygen demand were reduced by 42.6 and 35.2%. The xylanase-hydrogen peroxide combined treatment and conventional chlorine dioxide-alkaline (CDE1D1D2) bleaching showed almost similar improvement in physicochemical properties of bamboo pulp. Xylanase-peroxide bleaching reduces the lignin content to 4.95% from 13.32% unbleached pulp. This content after CDE1D1D2 treatment was 4.21%. The kappa number decreased from 15.2 to 9.46 with increasing the burst factor (15.51), crystallinity index (60.25%), viscosity (20.1 cp), and brightness (65.4%). The overall finding will encourage the development of new cleaner methods of bleaching in the paper and pulp industry.
- MeSH
- Bacillus * MeSH
- endo-1,4-beta-xylanasy MeSH
- lignin chemie MeSH
- peroxid vodíku MeSH
- sloni * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The most diverse and versatile endophytic actinobacteria are relatively unexplored potential sources of bioactive metabolites useful for different medical, agricultural, and other commercial applications. Their diversity in symbiotic association with traditionally utilized medicinal plants of northeast India is scantly available. The present investigation assessed the genetic diversity of endophytic actinobacteria (n = 120) distributed around the root, stem, and leaf tissues of six selected medicinal plants (Emblica officinalis, Terminalia chebula, T. arjuna, Murraya koenigii, Rauwolfia serpentina, and Azadirachta indica) from three different protected areas of evergreen forest-the Gibbon Wildlife Sanctuary (GWS), the Kaziranga National Park (KNP), and the North East Ecological Park (NEEP) of Assam, India. The samples were collected in two seasons (summer and winter). The overall phylogenetic analysis showed significant genetic diversity with 18 distinct genera belonging to 12 families. Overall, the occurrence of Streptomyces genus was predominant across all three sampling sites (76.66%), in both the sampling season (summer and winter). Shannon's and Simpson's diversity estimates showed their presence at A. indica (1.496, 0.778), R. serpentina (1.470, 0.858), and E. officinalis (0.975, 0.353). Among the site sampled, GWS had the most diverse community of actinobacteria (Shannon = 0.86 and Simpson = 0.557). The isolates were antagonistically more active against the investigated plant pathogenic bacteria than fungal pathogens. Further analysis revealed the prevalence of polyketide synthase genes (PKS) type II (84%) and PKS type I (16%) in the genome of the antimicrobial isolates. The overall findings confirmed the presence of biosynthetically active diverse actinobacterial members in the selected medicinal plants which offer potential opportunities towards the exploration of biologically active compounds.
- MeSH
- Actinobacteria klasifikace genetika izolace a purifikace fyziologie MeSH
- antibióza * MeSH
- Bacteria MeSH
- bakteriální proteiny genetika metabolismus MeSH
- endofyty klasifikace genetika izolace a purifikace fyziologie MeSH
- fylogeneze * MeSH
- fyziologie bakterií MeSH
- houby fyziologie MeSH
- léčivé rostliny mikrobiologie MeSH
- polyketidsynthasy genetika metabolismus MeSH
- roční období MeSH
- symbióza MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Indie MeSH
