Genus-specific secondary metabolome in Allokutzneria and Kibdelosporangium

Rare actinomycete genera are highly recognized as a promising source of structurally diverse and bioactive natural products.Among these genera,Allokutzneria and Kibdelosporangium are two phylogenetically closely related and have been reported to encode some valuable biosynthetic enzymes and secondary metabolites.However,there is currently no relevant systematic research available to outline the linkage of genomic and metabolomics for specific secondary metabolites in these two promising genera.In this study,we first investi-gated the genus-specific secondary metabolic potential in Allokutzneria and Kibdelosporangium by comparing the diversity and novelty of their secondary metabolite biosynthetic gene clusters(BGCs).The specific secondary metabolites produced by two representative strains of these genera were comprehensively investigated using untargeted metabolomics techniques.The findings unveiled that the majority(95.4%)of the gene cluster families(GCFs)encoded by Allokutzneria and Kibdelosporangium were genus-specific,including NRPS GCFs encoding siderophores.The untargeted metabolomics analysis revealed that the metabolic profiles of two representative strains exhibit extensive specificity,with the culture medium having a big impact on the metabolic profiles.Besides,an MS-cluster featuring a series of hydroxamate-type siderophores was identified from Allokutzneria albata JCM 9917,with two of them,including a novel one(N-deoxy arthrobactin A),being experimentally validated.The present study offers valuable insights for the targeted discovery of genus-specific natural products from microorganisms.

Hot working process optimization of Fe-20Mn-19Cr-0.5C-0.6N steel by activation energy, power dissipation and microstructural evolution

Hot deformation behavior of an Fe-20Mn-19Cr-0.5C-0.6N high-nitrogen austenitic steel has been studied by isothermal compression tests in deformation temperature range of 800-1200℃ and strain rate range of 0.01-10 s^-1. Results indicate that the Fe-20Mn-19Cr-0.5C-0.6N steel has high deformation resistance due to strong hindering effect on dislocation moving by nitrogen-induced lattice misfit. The twinning-induced plasticity effect is gradually suppressed with the increase in deformation temperature, and high-temperature plastic deformation mechanism by twinning is gradually replaced by dislocation planar slip. The deformation resistance is up to 343 MPa at deformation conditions of (1000 ℃, 0.01 s^-1), which is over 100 MPa higher than that in martensitic steel and 50 MPa higher than that in austenitic steel. Besides, value of deformation activation energy for the Fe-20Mn-19Cr-0.6N steel is up to 784 kJ mol^-1. Power dissipation efficiency is lower than 0.13, while hot processing map exhibits a very wide range of working area. The optimum hot working process obtains at deformation temperature range of 950-1200℃ and strain rate range of 0.01-10 s^-1, when deformation acti-vation energy is less than 662.6 kJ mol^-1, power dissipation efficiency exceeds 0.22, dynamic recrystallization fraction is over 46.1% and microstructures are without instable characteristics.