Cloning and Characterization of an Endoglucanase Gene from Actinomyces sp. Korean Native Goat 40

Expression, characterization, and activity optimization of a novel cellulase from the thermophilic bacteria Cohnella sp. A01

Cellulases are hydrolytic enzymes with wide scientific and industrial applications. We described a novel cellulase, CelC307, from the thermophilic indigenous Cohnella sp. A01. The 3-D structure of the CelC307 was predicted by comparative modeling. Docking of CelC307 with specific inhibitors and molecular dynamic (MD) simulation revealed that these ligands bound in a non-competitive manner. The CelC307 protein was purified and characterized after recombinant expression in Escherichia coli (E. coli) BL21. Using CMC 1% as the substrate, the thermodynamic values were determined as K_m 0.46 mM, k_cat 104.30 × 10^-3 (S^-1), and k_cat/K_m 226.73 (M^-1 S^-1). The CelC307 was optimally active at 40 °C and pH 7.0. The culture condition was optimized for improved CelC307 expression using Plackett-Burman and Box-Behnken design as follows: temperature 20 °C, pH 7.5, and inoculation concentration with an OD₆₀₀ = 1. The endoglucanase activity was positively modulated in the presence of Na⁺, Li⁺, Ca²⁺, 2-mercaptoethanol (2-ME), and glycerol. The thermodynamic parameters calculated for CelC307 confirmed its inherent thermostability. The characterized CelC307 may be a suitable candidate for various biotechnological applications.

Isolation and characterization of a mesophilic cellulolytic endophyte Preussia africana from Juniperus oxycedrus

The medicinal plant Juniperus oxycedrus is less recognized for the diversity of its fungal endophytes and their potential to produce extracellular enzymes. The present study is the first report on the isolation and identification of a mesophilic endophytic strain JO-A, Preussia africana, from fresh stems of the J. oxycedrus endemic tree in the Ifrane region-Morocco, and the evaluation of its ability to produce cellulases. A one-time multi-parameter one-factor screening was optimized to select factors that enhance cellulase production in P. africana. The maximum production of both CMCase and FPase activities were 1.913 IU.mL^-1 and 0.885 IU.mL^-1, respectively, when the medium was supplemented with 2% w/v glucose. These remarkable titers were tenfold greater than those obtained under the initial non-optimized conditions. This mesophilic P. africana JO-A strain grows and actively produces cellulases at 37 °C demonstrating its great potential for various biotechnology applications. The cellulolytic extract showed the highest enzymatic activities at pH 5.0 and 50 °C with a half-life of 24 h at 50 °C.

Some characters of bacterial cellulases in goats' rumen elucidated by metagenomic DNA analysis and the role of fibronectin 3 module for endoglucanase function

Objective

Fibronectin 3 (FN3) and immunoglobulin like modules (Ig) are usually collocated beside modular cellulase catalytic domains. However, very few researches have investigated the role of these modules. In a previous study, we have sequenced and analyzed bacterial metagenomic DNA in Vietnamese goats’ rumen and found that cellulase-producing bacteria and cellulase families were dominant. In this study, the properties of modular cellulases and the role of a FN3 in unique endoglucanase belonging to glycosyl hydorlase (GH) family 5 were determined.

Methods

Based on Pfam analysis, the cellulases sequences containing FN3, Ig modules were extracted from 297 complete open reading frames (ORFs). The alkaline, thermostability, tertiary structure of deduced enzymes were predicted by AcalPred, TBI software, Phyre2 and Swiss models. Then, whole and truncated forms of a selected gene were expressed in Escherichia coli and purified by His-tag affinity column for assessment of FN3 ability to enhance enzyme activity, solubility and conformation.

Results

From 297 complete ORFs coding for cellulases, 148 sequences containing FN3, Ig were identified. Mostly FN3 appeared in 90.9% beta-glucosidases belonging to glycosyl hydrolase family 3 (GH3) and situated downstream of catalytic domains. The Ig was found upstream of 100% endoglucanase GH9. Rarely FN3 was seen to be situated downstream of X domain and upstream of catalytic domain endoglucanase GH5. Whole enzyme (called XFN3GH5 based on modular structure) and truncate forms FN3, XFN3, FN3GH5, GH5 were cloned in pET22b (+) and pET22SUMO to be expressed in single and fusion forms with a small ubiquitin-related modifier partner (S). The FN3, SFN3 increased GH5 solubility in FN3GH5, SFN3GH5. The SFN3 partly served for GH5 conformation in SFN3GH5, increased modules interaction and enzyme-soluble substrate affinity to enhance SXFN3GH5, SFN3GH5 activities in mixtures. Both SFN3 and SXFN3 did not anchor enzyme on filter paper but exfoliate and separate cellulose chains on filter paper for enzyme hydrolysis.

Conclusion

Based on these findings, the presence of FN3 module in certain cellulases was confirmed and it assisted for enzyme conformation and activity in both soluble and insoluble substrate.

Efficient biomass saccharification using a novel cellobiohydrolase from Clostridium clariflavum for utilization in biofuel industry

The present study describes the cloning of the cellobiohydrolase gene from a thermophilic bacterium Clostridium clariflavum and its expression in Escherichia coli BL21(DE3) utilizing the expression vector pET-21a(+). The optimization of various parameters (pH, temperature, isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration, time of induction) was carried out to obtain the maximum enzyme activity (2.78 ± 0.145 U ml⁻¹) of recombinant enzyme. The maximum expression of recombinant cellobiohydrolase was obtained at pH 6.0 and 70 °C respectively. Enzyme purification was performed by heat treatment and immobilized metal anionic chromatography. The specific activity of the purified enzyme was 57.4 U mg⁻¹ with 35.17% recovery and 3.90 purification fold. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the molecular weight of cellobiohydrolase was 78 kDa. Among metal ions, Ca²⁺ showed a positive impact on the cellobiohydrolase enzyme with increased activity by 115%. Recombinant purified cellobiohydrolase enzyme remained stable and exhibited 77% and 63% residual activity in comparison to control in the presence of n-butanol and after incubation at 80 °C for 1 h, respectively. Our results indicate that our purified recombinant cellobiohydrolase can be used in the biofuel industry.

Successful expression of a novel cellobiohydrolase enzyme from Clostridium clariflavum with efficient saccharification potential of plant biomass for the biofuel industry.

Molecular cloning, heterologous expression, and functional characterization of a cellulolytic enzyme (Cel PRII) from buffalo rumen metagenome

A cellulase encoding gene, Cel PRII, was identified from Mehsani buffalo rumen metagenome, and cloned and expressed in Escherichia coli BL21(DE3)pLysS. The 1170 bp full length gene encodes a 389 residue polypeptide (Cel PRII) containing a catalytic domain belonging to glycosyl hydrolase (GH) 5 family. The fusion protein consisting of the Cel PRII, thioredoxin tag and 6x Histidine tag with predicted molecular weight of 63 kDa when recovered from inclusion bodies under denaturing conditions, exhibited cellulolytic activity against carboxymethyl cellulose (CMC). Recombinant Cel PRII was stable in the pH range 4.0-10.0 with pH optima 6.0. The optimal reaction temperature of Cel PRII was 30 °C with more than 50% of its activity retained at the temperatures ranging from 0 to 50 °C. Cel PRII exhibited enhanced enzymatic activity in the presence of Mn²⁺ ions and was inhibited in the presence of chelating agent EDTA. The K _m and V _max values for CMC were found to be 166 mg/mL and 1292 IU/mg, respectively. Cel PRII identified in the present study may act as an excellent candidate for industrial applications, and may aid in lignocellulosic biomass conversion because of its potential cellulolytic activity, thermostability, and excellent pH stability.

Genetic diversity and patterns of population structure in Creole goats from the Americas

Biodiversity studies are more efficient when large numbers of breeds belonging to several countries are involved, as they allow for an in-depth analysis of the within- and between-breed components of genetic diversity. A set of 21 microsatellites was used to investigate the genetic composition of 24 Creole goat breeds (910 animals) from 10 countries to estimate levels of genetic variability, infer population structure and understand genetic relationships among populations across the American continent. Three commercial transboundary breeds were included in the analyses to investigate admixture with Creole goats. Overall, the genetic diversity of Creole populations (mean number of alleles = 5.82 ± 1.14, observed heterozygosity = 0.585 ± 0.074) was moderate and slightly lower than what was detected in other studies with breeds from other regions. The Bayesian clustering analysis without prior information on source populations identified 22 breed clusters. Three groups comprised more than one population, namely from Brazil (Azul and Graúna; Moxotó and Repartida) and Argentina (Long and shorthair Chilluda, Pampeana Colorada and Angora-type goat). Substructure was found in Criolla Paraguaya. When prior information on sample origin was considered, 92% of the individuals were assigned to the source population (threshold q ≥ 0.700). Creole breeds are well-differentiated entities (mean coefficient of genetic differentiation = 0.111 ± 0.048, with the exception of isolated island populations). Dilution from admixture with commercial transboundary breeds appears to be negligible. Significant levels of inbreeding were detected (inbreeding coefficient > 0 in most Creole goat populations, P < 0.05). Our results provide a broad perspective on the extant genetic diversity of Creole goats, however further studies are needed to understand whether the observed geographical patterns of population structure may reflect the mode of goat colonization in the Americas.