Exploration of Protease Resources in the Gut of Omnivorous Gryllotalpa orientalis (Orthoptera: Gryllotalpidae).

Simple Summary: The digestive enzymes present in the insect gut play a crucial role in digesting food and extracting essential nutrients. The diverse range of digestive enzymes found in the insect gut serves as a valuable source of functional proteins. With a significant population of herbivorous insects, there has been extensive research on cellulase in the insect gut. This study utilized both culture-independent and culture-dependent methods to investigate the protease resources responsible for digesting animal and plant proteins, laying a solid foundation for future research and utilization of proteases derived from insect sources. An insect's gut microbiome is an essential "organ" in their life cycle, playing a crucial role by aiding food digestion and nutrient absorption. This study employed both culture-independent and culture-dependent methods to explore the protease resources present in the gut of the omnivorous insect Gryllotalpa orientalis. The findings revealed that the gut extract of G. orientalis contained a diverse array of proteases, including cysteine proteases, pepsin, serine proteases, and trypsin, as well as some unidentified proteases. Furthermore, the protease gene htpX, derived from gut bacterium Priestia megaterium DX-3, has been cloned and recombinantly expressed. The recombinant DX-3-htpX protease exhibited a 61.9-fold increase in fermentation level compared to the DX-3 protease. This protease was characterized as a neutral, heat-resistant metalloprotease with an M48 peptidase domain, and it was observed that the binding of Ca2+ to the recombinant protease resulted in the formation of the largest active pocket. This study provides technical support for further development and utilization of functional protein resources in insect gut. [ABSTRACT FROM AUTHOR]