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Mesophilic and cryogenic actinomycetes were isolated from water, quagmire soil, lakeside soil and saline wasteland soil in the Qinghai Lake by spreading samples on three kinds of agar media, in which content of NaCl was 70 g/ L. They were characterized according to routine methods, and detected their salt-tolerance. The results indicated that there were salt-tolerant, mesophilic and cryogenic actinomycetes in quagmire and lakeside soil of the Qinghai Lake and in saline wasteland soil nearby the Qinghai Lake. The amount in wasteland soil was the largest, followed by lakeside and swamp soil. All of the salt-tolerant actinomycetes identified were Streptomyces (92. 6 % of total), and they were all albsporus. And 47.6 %, 19.0 %, and 33.3 % of the tested actinomycetes could tolerant NaCl concentration at 70 g/ L, 100 g/L, and 150 g/L respectively. Keywords: Actinomycetes distribution, Salt-tolerant, Qinghai Lake, Actinomycetes is an important class of microbial resources, they are important producers of antibiotics and other important bioactive substances. So far, about two-thirds of the world's antibiotics were secreted by [...]

To elucidate how soft rot disease affects soil characteristics and root-associated, culturable microorganisms in Amorphophallus konjac stands, the responses of soil around roots of A. konjac with soft rot disease were investigated in stands with and without soft rot. Changes in the root-associated culturable microbial community and diversity were investigated by dilution plating. Soil characteristics were compared between stands using standard techniques. A. konjac with soft rot had higher concentrations of available soil P and K, NH-N, organic matter and water content and lower pH compared with plants without. The community composition of root-associated culturable microorganisms differed between stands with and without soft rot. The microbial community associated with soft rot in A. konjac was characterized by four types of abundant microorganisms ( Fusarium solani, Fusarium oxysporum, Pseudomonas chlororaphis subsp. aureofaciens and Stenotrophomonas pavanii) and three types of less-abundant microorganisms ( Rhizobium radiobacter, Bacillus thuringiensis and Streptomyces cellulosae), and a small number of Bacillus and Streptomyces species in the rhizosphere and rhizoplane soils. Particular microbial combinations were diametrically opposed between plants with and without soft rot. The richness and diversity of root-associated culturable microorganisms were higher in the stand without soft rot than in the stand with soft rot. A. konjac soft rot led to obvious differences in the diversity and community composition of root-associated culturable microorganisms and in soil characteristics. [ABSTRACT FROM AUTHOR]

Orobanche cumana Wallr. is a holoparasite weed that extracts water and nutrients from its host the sunflower, thereby causing yield reductions and quality losses. However, the number of O. cumana parasites in the same farmland is distinctly different. The roots of some hosts have been heavily parasitized, while others have not been parasitized. What are the factors contributing to this phenomenon? Is it possible that sunflower interroot microorganisms are playing a regulatory role in this phenomenon? The role of the microbial community in this remains unclear. In this study, we investigated the rhizosphere soil microbiome for sunflowers with different degrees of O. cumana parasitism, that is, healthy, light infection, moderate infection, and severe infection on the sunflower roots. The microbial structures differed significantly according to the degree of parasitism, where Xanthomonadaceae was enriched in severe infections. Metagenomic analyses revealed that amino acid, carbohydrate, energy, and lipid metabolism were increased in the rhizosphere soils of severely infected sunflowers, which were attributed to the proliferation of Lysobacter . Lysobacter antibioticus (HX79) was isolated and its capacity to promote O. cumana seed germination and increase the germ tube length was confirmed by germination and pot experiments. Cyclo(Pro-Val), an active metabolite of strain HX79, was identified and metabolomic and molecular docking approaches confirmed it was responsible for promoting O. cumana seed germination and growth. And we found that Pseudomonas mandelii HX1 inhibited the growth of O. cumana in the host rhizosphere soil. Our findings clarify the role of rhizosphere microbiota in regulating the parasite O. cumana to possibly facilitate the development of a new weed suppression strategy., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. iMeta published by John Wiley & Sons Australia, Ltd on behalf of iMeta Science.)

Objective: To disrupt spa7074, which encodes a member of the TetR family transcriptional factors, in biocontrol strain Act12 and characterize the secondary metabolites in the mutant strain., Methods: We disrupted the gene spa7074 by homologous recombination. The secondary metabolites of the mutant strain Δspa7074 and Act12 were detected by HPLC. The structure was analyzed by MS and NMR., Results: Compared to the wild-type strain, the production of some unknown compounds in the mutant strain Δspa7074 increased obviously. We purified one of the compounds and identified as oligomycin D by MS and NMR analysis., Conclusion: An oligomycin D-producing strain Δspa7074 was derived via genetic engineering.

Objective: We used ultrasonic to treat soil samples to isolate rare actinomycetes strains., Methods: We collected and suspended soil samples from mix tropical-rain-forest in Xishuangbanna. Farther, we treated the soil suspension with ultrasound for 10 to 120 s and used the plate dilution method to isolate actinomycetes. After got pure colonies, we sequenced their 16S rRNA gene sequences and calculated to put in phylogenetic analysis. The isolates were identified to the genus. We treated 10 kinds of common and identified Streptomyces with 1 - 5 min using ultrasonic, and then were cultured to measure their survival rate., Results: The soil suspensions treated with different times by the ultrasonic, actinomycetes gradual increased in the number and types. Ultrasonic treating of known Streptomyces with 0-5 min, there was no significant effect on the survival number of Streptomyces., Conclusion: The ultrasonic treating with soil suspensions for 40 s can significantly increase the total number of actinomycetes and the types of rare actinomycetes. Thereby, it is an economic and simple method to apparently increase the types of rare actinomycetes in the isolation.