Advances in Microbial Strains and Bedding Materials in a Deep-Litter System for Pig Breeding

The selection and compatibility of the microbial strains and bedding materials in a deep-litter system is the primary issues for this ecological breeding technology. In this paper, we analyzed and summarized the categories of microbial strains and bedding materials suitable for a deep-litter system, the fermentation properties of different microbes, the parameter requirements of bedding materials, and the fermentation process led by functional microbial flora in a deep-litter system, with the objective to provide theoretical bases and practical guidance for the promotion of deep-litter breeding method nationwide.

Optimization of cryopreservation of pathogenic microbial strains

The preservation of pathogenic microbial strains is of great significance for basic research in microbiology and utilization of microbial resources.Appropriate preservation methods can maintain high survival rate and genetic stability of pathogenic microbial strains for a long time.This study summarizes the current status of preservation of strains,discusses the limitations and damaging factors of cryopreservation and prospects for optimization,and explores the mechanism of cryopreservation of strains.Our main objective is to provide a reference for the long-term effective preservation of microbial resources and guarantee of national biosafety.

Divergent responses of growth rate and antioxidative system of ten Bacillus strains to acid stresses

Response of growth rate and antioxidative system of ten Bacillus strains to acid stresses was assayed.Strong acid treatment significantly decreased the growth rate of the strains.Acid stresses increased the GPX activity and GSSG content of the tested strains.Divergent changes occurred in ROS and antioxidative system(SOD,CAT,GR,MDA and GSH).Environmental changes including soil acidification exert obvi-ous stresses on soil ecosystems and influence soil microor-ganisms.In this study,ten microbial strains were incubated under different acid treatments to investigate responses of microbial growth and antioxidative system to acid stress.All the strains belong to Bacillus genus,but exhibit distinct ecological functions.We observed that these microbial strains had obviously different pH tolerance threshold,in spite of the close phylogenetic classification among strains.Acid stresses exerted significant effects on microbial antiox-idative system,including superoxide dismutase(SOD),cata-lase(CAT)and glutathione transferring enzymes(GPX and GR)and reactants(GSH and GSSH),but the effects were strain specific.Furthermore,we found acid stress effects on total variances of the investigated microbial antioxidative system along the first two principal components(PCs).Activities of CAT and SOD contributed substantially to PC1 that reflected obvious acid effects on NC7 and ZC4,and closely related to intracellular malondialdehyde content.The GSSG activities and GSH/GSSG contributed greatly to PC2 that unveiled acid stress effects on most of the microbial strains.Our results highlight substantially heterogeneous responses of microbial strains to acid stress and support that phylogenetic closeness does not imply functional similarity of soil microorganisms under environmental changes.