Pediococcus pentosaceus ZZ61 enhances growth performance and pathogenic resistance of silkworm Bombyx mori by regulating gut microbiota and metabolites.

Probiotics have attracted considerable attention in animal husbandry due to their positive effect on animal growth and health. This study aimed to screen candidate probiotic strain promoting the growth and health of silkworm and reveal the potential mechanisms. A novel probiotic Pediococcus pentosaceus strain (ZZ61) substantially promoted body weight gain, feed efficiency, and silk yield. These effects were likely mediated by changes in the intestinal digestive enzyme activity and nutrient provisioning (e.g., B vitamins) of the host, improving nutrient digestion and assimilation. Additionally, P. pentosaceus produced antimicrobial compounds and increased the antioxidant capacity to protect the host against pathogenic infection. Furthermore, P. pentosaceus affected the gut microbiome and altered the levels of gut metabolites (e.g., glycine and glycerophospholipids), which in turn promotes host nutrition and health. This study contributes to an improved understanding of the interactions between probiotic and host and promotes probiotic utilization in sericulture.

The Bombyx mori singed Gene Is Involved in the High-Temperature Resistance of Silkworms.

Temperature is an important factor in the growth, development, survival, and reproduction of organisms. The high-temperature resistance mechanism of insects may be significant for use in the prevention and control of insect pests. The silkworm, Bombyx mori, is an important Lepidoptera model species for studies on pest control in agriculture and forestry. We identified a gene in B. mori, the B. mori singed (Bmsn) gene, which is involved in the high-temperature resistance of silkworms. Sn proteins are highly conserved among species in many taxonomic groups. The overexpression of the Bmsn gene promoted the proliferation of silkworm cells, reduced oxidation, and reduced the accumulation of reactive oxygen species under stress. Interfering with the Bmsn gene had the opposite result. We constructed a transgenic B. mori strain that overexpressed the Bmsn gene. The physiological traits of the transgenic strain were significantly improved, and it had stronger high-temperature resistance. The Bmsn gene is involved in the process by which fat bodies respond to high-temperature stress. These findings provide insights into the mechanism of high-temperature resistance of insects and offer a new perspective on agricultural and forestry pest control.

Thermal Stability Enhancement of L-Asparaginase from Corynebacterium glutamicum Based on a Semi-Rational Design and Its Effect on Acrylamide Mitigation Capacity in Biscuits.

Acrylamide is present in thermally processed foods, and it possesses toxic and carcinogenic properties. L-asparaginases could effectively regulate the formation of acrylamide at the source. However, current L-asparaginases have drawbacks such as poor thermal stability, low catalytic activity, and poor substrate specificity, thereby restricting their utility in the food industry. To address this issue, this study employed consensus design to predict the crucial residues influencing the thermal stability of Corynebacterium glutamicum L-asparaginase (CgASNase). Subsequently, a combination of site-point saturating mutation and combinatorial mutation techniques was applied to generate the double-mutant enzyme L42T/S213N. Remarkably, L42T/S213N displayed significantly enhanced thermal stability without a substantial impact on its enzymatic activity. Notably, its half-life at 40 °C reached an impressive 13.29 ± 0.91 min, surpassing that of CgASNase (3.24 ± 0.23 min). Moreover, the enhanced thermal stability of L42T/S213N can be attributed to an increased positive surface charge and a more symmetrical positive potential, as revealed by three-dimensional structural simulations and structure comparison analyses. To assess the impact of L42T/S213N on acrylamide removal in biscuits, the optimal treatment conditions for acrylamide removal were determined through a combination of one-way and orthogonal tests, with an enzyme dosage of 300 IU/kg flour, an enzyme reaction temperature of 40 °C, and an enzyme reaction time of 30 min. Under these conditions, compared to the control (464.74 ± 6.68 µg/kg), the acrylamide reduction in double-mutant-enzyme-treated biscuits was 85.31%, while the reduction in wild-type-treated biscuits was 68.78%. These results suggest that L42T/S213N is a promising candidate for industrial applications of L-asparaginase.