Enzymes of microbial origin are of immense importance for organic material decomposition leading to bioremediation of organic waste, bioenergy generation, large-scale industrial bioprocesses, etc. The market demand for microbial cellulase enzyme is growing more rapidly which ultimately becomes the driving force towards research on this biocatalyst, widely used in various industrial activities. The use of novel cellulase genes obtained from various thermophiles through metagenomics and genetic engineering as well as following metabolic engineering pathways would be able to enhance the production of thermophilic cellulase at industrial scale. The present review is mainly focused on thermophilic cellulolytic bacteria, discoveries on cellulase gene, genetically modified cellulase, metabolic engineering, and their various industrial applications. A lot of lacunae are yet to overcome for thermophiles such as metagenome analysis, metabolic pathway modification study, search of heterologous hosts in gene expression system, and improved recombinant strain for better cellulase yield as well as value-added product formation.
Soil microorganisms are important mediators of carbon cycling in nature. Although cellulose- and hemicellulose-degrading bacteria have been isolated from Algerian ecosystems, the information on the composition of soil bacterial communities and thus the potential of their members to decompose plant residues is still limited. The objective of the present study was to describe and compare the bacterial community composition in Algerian soils (crop, forest, garden, and desert) and the activity of cellulose- and hemicellulose-degrading enzymes. Bacterial communities were characterized by high-throughput 16S amplicon sequencing followed by the in silico prediction of their functional potential. The highest lignocellulolytic activity was recorded in forest and garden soils whereas activities in the agricultural and desert soils were typically low. The bacterial phyla Proteobacteria (in particular classes α-proteobacteria, δ-proteobacteria, and γ-proteobacteria), Firmicutes, and Actinobacteria dominated in all soils. Forest and garden soils exhibited higher diversity than agricultural and desert soils. Endocellulase activity was elevated in forest and garden soils. In silico analysis predicted higher share of genes assigned to general metabolism in forest and garden soils compared with agricultural and arid soils, particularly in carbohydrate metabolism. The highest potential of lignocellulose decomposition was predicted for forest soils, which is in agreement with the highest activity of corresponding enzymes.
- MeSH
- Bacteria klasifikace enzymologie genetika izolace a purifikace MeSH
- bakteriální proteiny genetika metabolismus MeSH
- celulasa genetika metabolismus MeSH
- ekosystém MeSH
- fylogeneze MeSH
- glykosidhydrolasy genetika metabolismus MeSH
- lesy MeSH
- půda chemie MeSH
- půdní mikrobiologie * MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Alžírsko MeSH
Radial growth, asexual sporulation, and cleistothecia formation as well as extracellular chitinase and proteinase formation of Aspergillus nidulans were monitored in surface cultures in order to study the physiological role of extracellular hydrolase production in carbon-stressed cultures. We set up carbon-stressed and carbon-overfed experimental conditions by varying the starting glucose concentration within the range of 2.5 and 40 g/L. Glucose starvation induced radial growth and hydrolase production and enhanced the maturation of cleistothecia; meanwhile, glucose-rich conditions enhanced mycelial biomass, conidia, and cleistothecia production. Double deletion of chiB and engA (encoding an extracellular endochitinase and a β-1,3-endoglucanase, respectively) decreased conidia production under carbon-stressed conditions, suggesting that these autolytic hydrolases can support conidia formation by releasing nutrients from the cell wall polysaccharides of dead hyphae. Double deletion of prtA and pepJ (both genes encode extracellular proteases) reduced the number of cleistothecia even under carbon-rich conditions except in the presence of casamino acids, which supports the view that sexual development and amino acid metabolism are tightly connected to each other in this fungus.
- MeSH
- Aspergillus nidulans enzymologie růst a vývoj MeSH
- celulasa genetika MeSH
- chitinasy genetika MeSH
- fungální proteiny genetika MeSH
- glukosa chemie MeSH
- hydrolasy genetika MeSH
- hyfy růst a vývoj MeSH
- kultivační média MeSH
- mutace MeSH
- proteasy genetika MeSH
- regulace genové exprese enzymů MeSH
- regulace genové exprese u hub * MeSH
- spory hub růst a vývoj MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
This study aimed to isolate and characterize a novel cellulolytic enzyme from black goat rumen by using a culture-independent approach. A metagenomic fosmid library was constructed from black goat rumen contents and screened for a novel cellulase. The KG37 gene encoding a protein of 858 amino acid residues (92.7 kDa) was isolated. The deduced protein contained a glycosyl hydrolase family 74 (GH74) domain and showed 77% sequence identity to two endo-1,4-β-glucanases from Fibrobacter succinogenes. The novel GH74 cellulase gene was overexpressed in Escherichia coli, and its protein product was functionally characterized. The recombinant GH74 cellulase showed a broad substrate spectrum. The enzyme exhibited its optimum activity at pH 5.0 and temperature range of 20-50 °C. The enzyme was thermally stable at pH 5.0 and at a temperature of 20-40 °C. The novel GH74 cellulase can be practically exploited to convert lignocellulosic biomass to value-added products in various industrial applications in future.
- MeSH
- bachor mikrobiologie MeSH
- celulasa chemie genetika izolace a purifikace MeSH
- Escherichia coli genetika metabolismus MeSH
- exprese genu MeSH
- Fibrobacter enzymologie genetika MeSH
- genetické testování MeSH
- genová knihovna MeSH
- klonování DNA MeSH
- koncentrace vodíkových iontů MeSH
- kozy mikrobiologie MeSH
- metagenom * MeSH
- metagenomika MeSH
- molekulová hmotnost MeSH
- rekombinantní proteiny genetika izolace a purifikace metabolismus MeSH
- sekvenční homologie MeSH
- stabilita enzymů MeSH
- substrátová specifita MeSH
- teplota MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Identification of bacteria that produce carbohydrolytic enzymes is extremely important given the increased demand for these enzymes in many industries. Twenty lignocellulose-degrading bacterial isolates from Algerian compost and different soils were screened for their potential to produce different enzymes involved in biomass deconstruction. Based on 16S rRNA gene sequencing, the isolates belonged to Proteobacteria and Actinobacteria. Differences among species were reflected both as the presence/absence of enzymes or at the level of enzyme activity. Among the most active species, Bosea sp. FBZP-16 demonstrated cellulolytic activity on both amorphous cellulose (CMC) and complex lignocellulose (wheat straw) and was selected for whole-genomic sequencing. The genome sequencing revealed the presence of a complex enzymatic machinery required for organic matter decomposition. Analysis of the enzyme-encoding genes indicated that multiple genes for endoglucanase, xylanase, β-glucosidase and β-mannosidase are present in the genome with enzyme activities displayed by the bacterium, while other enzymes, such as certain cellobiohydrolases, were not detected at the genomic level. This indicates that a combination of functional screening of bacterial cultures with the use of genome-derived information is important for the prediction of potential enzyme production. These results provide insight into their possible exploitation for the production of fuels and chemicals derived from plant biomass.
- MeSH
- Actinobacteria genetika izolace a purifikace MeSH
- bakteriální proteiny genetika metabolismus MeSH
- celulasa genetika metabolismus MeSH
- celulosa metabolismus MeSH
- fylogeneze MeSH
- glykosidhydrolasy genetika metabolismus MeSH
- lignin metabolismus MeSH
- Proteobacteria genetika izolace a purifikace MeSH
- půda MeSH
- půdní mikrobiologie MeSH
- Rhizobiaceae enzymologie genetika izolace a purifikace MeSH
- RNA ribozomální 16S genetika MeSH
- sekvenční analýza RNA metody MeSH
- Publikační typ
- časopisecké články MeSH
A metagenomic fosmid library was constructed from compost microbial communities that were collected from various farms throughout the Khon Kaen province, Thailand. The library was enriched in carboxymethylcellulose (CM-cellulose)--containing media prior to the screening of clones capable of degrading cellulosic materials. Two clones were selected for further subcloning and sequencing based on different patterns from restriction analysis. Deduced amino acid analysis of possible ORFs revealed one novel gene encoding an enzyme belonging to glycosyl hydrolase family 43 (GH43), which is a GH family rarely found in metagenomic studies. The most notable finding is that this enzyme, designated as Biof1_09, shows dual activities, namely endocellulase and endoxylanase activities. Biof1_09 showed greater than 50% of its activity under acidic conditions ranging from pH 3.5 to 5.5 with a pH optimum of 4.5. The optimum temperature of this enzyme was between 45 and 55 °C with an optimum of 50 °C. The properties of Biof1_09 make this enzyme an attractive candidate for large-scale expression for use in lignocellulose degradation for various bioprocess applications, including bioethanol fermentation.
- MeSH
- celulasa genetika metabolismus MeSH
- genová knihovna MeSH
- koncentrace vodíkových iontů MeSH
- metagenom * MeSH
- molekulární sekvence - údaje MeSH
- otevřené čtecí rámce MeSH
- půda * MeSH
- půdní mikrobiologie * MeSH
- sekvenční analýza DNA MeSH
- sekvenční homologie aminokyselin MeSH
- stabilita enzymů MeSH
- teplota MeSH
- xylosidasy genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Thajsko MeSH
The facultative anaerobic bacterium Lactococcus lactis has been used as a host for expression of a gene isolated from the anaerobic rumen fungus Neocallimastix sp. The coding region of the cellulase gene was obtained from the fungus with the aid of polymerase chain reaction amplification. The gene was then transformed into pCT vector system and the constructed recombinant plasmid was introduced into two L. lactis strains (IL403 and MG1363) by electroporation. The gene encoding the fungal originated cellulase was expressed in both strains successfully although the expression level was relatively lower in comparison with the original enzyme activity. Genetically modified L. lactis strains were used as silage inoculants for pre-biodegradation of the plant biomass during ensiling. That treatment resulted in a notable reduction of the acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of the plant biomass used as silage material. Inoculation with recombinant strain IL1043 resulted in 4.8 and 9.7 % decrease in NDF and ADF contents, respectively while the inoculation of silage with strain MG1363 decreased the ADF content by >5 %.
