Cellulase production and efficient saccharification of biomass by a new mutant Trichoderma afroharzianum MEA-12

Kinetic and thermodynamic investigation of Rhodanese synthesized by enhanced Klebsiella oxytoca JCM 1665 strain: a comparative between the free and immobilized enzyme entrapped in alginate beads

Klebsiella oxytoca JCM 1665 was subjected to extracellular rhodanese production using a submerged fermentation technique. The organism was further engineered for higher cyanide tolerance and rhodanese yield using ethylmethanesulfonate as a mutagen. Mutagenesis resulted in an improved mutant with high cyanide tolerance (100 mM) and rhodanese yield (26.7 ± 0.67 U/mL). This yield was 4.34-fold higher than the wild strain (6.15 ± 0.65 U/mL). At temperatures ranging from 30 to 80 °C, the first-order thermal denaturation constant (Kd) for free enzyme increases from 0.00818 to 0.0333 min-1 while the immobilized enzyme increases from 0.003 to 0.0204 min-1. The equivalent half-life reduces from 99 to 21 minutes and 231 to 35 minutes, respectively. Residual activity tests were used to assess the thermodynamic parameters for both enzyme preparations. For the free enzyme, the parameters obtained were enthalpy (29.40 to 29.06 kJ.mol-1), entropy (-194.24 to -197.50 J.mol-1K-1) and Gibbs free energy (90.20 to 98.80 kJ.mol-1). In addition, for immobilized rhodanese, we obtained enthalpy (40.40 to 40.07 kJ.mol-1), entropy (-164.21 to - 165.20 J.mol-1K-1) and Gibbs free energy (91.80 to 98.40 kJ.mol-1. Regarding its operational stability, the enzyme was able to maintain 63% of its activity after being used for five cycles. Immobilized K. oxytoca rhodanese showed a marked resistance to heat inactivation compared to free enzyme forms; making it of utmost significance in many biotechnological applications.

Non-deteriorative eco-friendly water-saving tactic for removal of vegetable matters from wool fleece using xylanase and cellulase

The carbonization of wool fleece (WF) is conducted to remove the adhered vegetable matter (VM) from contaminated WF using sulfuric acid, followed by drying and backing. This process has a deteriorative effect on WF and requires a tremendous quantity of water for rinsing WF after carbonization to remove any H2SO4 residuals. Herein, we propose an alternative eco-friendly water-saving process for the removal of VM from WF using enzymes. Cellulase-containing xylanase from the fungus Aspergillus terreus, and cellulase-free xylanase from the fungus Aspergillus flavus AW1 were used to remove the VM from WF. The effect of some process parameters on the amount of the removed VM was assessed. Alkali solubility as well as sulfur and cystine content were used to follow the alteration in the chemistry of the bio-treated WF. The fiber morphology was examined using scanning electron microscopy. The dyeability of the treated WF towards acid, reactive, and basic dyes was monitored. The results revealed that the removal of the VM from WF by applying the examined enzymes was effective and could be an appropriate, non-destructive, eco-friendly water-saving substitute to the conventional carbonization procedures. By virtue of enzyme specificity, the proposed process removed the VM without deteriorating the fiber.

Fused expression of Sm1-Chit42 proteins for synergistic mycoparasitic response of Trichoderma afroharzianum on Botrytis cinerea

Sm1 and Chit42 of Trichoderma have been universally confirmed as crucial biocontrol factors against pathogen infection through induced resistance and mycoparasitism, respectively. However, not enough work has been conducted to understand the novel function of fused expression of these two proteins in Trichoderma. The results of this study demonstrated that Sm1-Chit42 protein (SCf) engineered T. afroharzianum strain OE:SCf exerted synergistic inhibition to Botrytis cinerea growth at multiple stages of mycoparasitic interaction of T. afroharzianum and B. cinerea including chemotropism sensing, hyphal coiling, hydrophobicity modulation, cell wall adhesion, virulence reduction and pathogen killing by ROS. These results highlight a novel mycoparasitic system in Trichoderma strains engineered with Sm1-Chit42 chimeric protein to combat B. cinerea growth and reproduction, which would lay a strong foundation for exploring a new engineered Trichoderma biofungicide created with chimeric proteins in the future.

Application of Atmospheric and Room-Temperature Plasma (ARTP) to Microbial Breeding

Atmospheric and room-temperature plasma (ARTP) is an efficient microbial mutagenesis method with broad application prospects. Compared to traditional methods, ARTP technology can more effectively induce DNA damage and generate stable mutant strains. It is characterized by its simplicity, cost-effectiveness, and avoidance of hazardous chemicals, presenting a vast potential for application. The ARTP technology is widely used in bacterial, fungal, and microalgal mutagenesis for increasing productivity and improving characteristics. In conclusion, ARTP technology holds significant promise in the field of microbial breeding. Through ARTP technology, we can create mutant strains with specific genetic traits and improved performance, thereby increasing yield, improving quality, and meeting market demands. The field of microbial breeding will witness further innovation and progress with continuous refinement and optimization of ARTP technology.

Cellulase-lactic acid bacteria synergy action regulates silage fermentation of woody plant

BACKGROUND

Feed shortage is an important factor limiting livestock production in the world. To effectively utilize natural woody plant resources, we used wilting and microbial additives to prepare an anaerobic fermentation feed of mulberry, and used PacBio single-molecule real-time (SMRT) sequencing technology to analyse the "enzyme-bacteria synergy" and fermentation mechanism.

RESULTS

The fresh branches and leaves of mulberry have high levels of moisture and nutrients, and also contain a diverse range of epiphytic microorganisms. After ensiling, the microbial diversity decreased markedly, and the dominant bacteria rapidly shifted from Gram-negative Proteobacteria to Gram-positive Firmicutes. Lactic acid bacteria (LAB) emerged as the dominant microbial population, resulting in increased in the proportion of the carbohydrate metabolism and decreased in the proportion of the amino acid and "global and overview map" (GOM) metabolism categories. The combination of cellulase and LAB exhibited a synergistic effect, through which cellulases such as glycanase, pectinase, and carboxymethyl cellulase decomposed cellulose and hemicellulose into sugars. LAB converted these sugars into lactic acid through the glycolytic pathway, thereby improving the microbial community structure, metabolism and fermentation quality of mulberry silage. The GOM, carbohydrate metabolism, and amino acid metabolism were the main microbial metabolic categories during ensiling. The presence of LAB had an important effect on the microbial community and metabolic pathways during silage fermentation. A "co-occurrence microbial network" formed with LAB, effectively inhibiting the growth of harmful microorganisms, and dominating the anaerobic fermentation process.

CONCLUSIONS

In summary, PacBio SMRT was used to accurately analyse the microbial network information and regulatory mechanism of anaerobic fermentation, which provided a scientific basis for the study of woody silage fermentation theory. This study reveals for the first time the main principle of the enzyme-bacteria synergy in a woody silage fermentation system, which provides technical support for the development and utilization of woody feed resources, and achieves sustainable livestock production.

Contribution of Enzyme Catalysis to the Achievement of the United Nations' Sustainable Development Goals

In September 2015, the United Nations General Assembly established the 2030 Agenda for Sustainable Development, which includes 17 Sustainable Development Goals (SDGs) [...].