Characterization of regulatory genes Plhffp and Plpif1 involved in conidiation regulation in Purpureocillium lavendulum.

Purpureocillium lavendulum is an important biocontrol agent against plant-parasitic nematodes, primarily infecting them with conidia. However, research on the regulatory genes and pathways involved in its conidiation is still limited. In this study, we employed Agrobacterium tumefaciens-mediated genetic transformation to generate 4,870 random T-DNA insertion mutants of P. lavendulum. Among these mutants, 131 strains exhibited abnormal conidiation, and further in-depth investigations were conducted on two strains (designated as #5-197 and #5-119) that showed significantly reduced conidiation. Through whole-genome re-sequencing and genome walking, we identified the T-DNA insertion sites in these strains and determined the corresponding genes affected by the insertions, namely Plhffp and Plpif1. Both genes were knocked out through homologous recombination, and phenotypic analysis revealed a significant difference in conidiation between the knockout strains and the wild-type strain (ku80). Upon complementation of the ΔPlpif1 strain with the corresponding wildtype allele, conidiation was restored to a level comparable to ku80, providing further evidence of the involvement of this gene in conidiation regulation in P. lavendulum. The knockout of Plhffp or Plpif1 reduced the antioxidant capacity of P. lavendulum, and the absence of Plhffp also resulted in decreased resistance to SDS, suggesting that this gene may be involved in the integrity of the cell wall. RT-qPCR showed that knockout of Plhffp or Plpif1 altered expression levels of several known genes associated with conidiation. Additionally, the analysis of nematode infection assays with Caenorhabditis elegans indicated that the knockout of Plhffp and Plpif1 indirectly reduced the pathogenicity of P. lavendulum towards the nematodes. The results demonstrate that Agrobacterium tumefaciens - mediated T-DNA insertion mutagenesis, gene knockout, and complementation can be highly effective for identifying functionally important genes in P. lavendulum.

Mycolicibacterium arseniciresistens sp. nov., isolated from lead-zinc mine tailing, and reclassification of two Mycobacterium species as Mycolicibacterium palauense comb. nov. and Mycolicibacterium grossiae comb. nov.

A Gram-positive, acid-fast, aerobic, rapidly growing and non-motile strain was isolated from lead-zinc mine tailing sampled in Lanping, Yunnan province, Southwest China. 16S rRNA gene sequence analysis showed that the most closely related species of strain KC 300T was Mycolicibacterium litorale CGMCC 4.5724T (98.47 %). Additionally, phylogenomic and specific conserved signature indel analysis revealed that strain KC 300T should be a member of genus Mycolicibacterium, and Mycobacterium palauense CECT 8779T and Mycobacterium grossiae DSM 104744T should also members of genus Mycolicibacterium. The genome size of strain KC 300T was 6.2 Mb with an in silico DNA G+C content of 69.2 mol%. Chemotaxonomic characteristics of strain KC 300T were also consistent with the genus Mycolicibacterium. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values, as well as phenotypic, physiological and biochemical characteristics, support that strain KC 300T represents a new species within the genus Mycolicibacterium, for which the name Mycolicibacterium arseniciresistens sp. nov. is proposed, with the type strain KC 300T (=CGMCC 1.19494T=JCM 35915T). In addition, we reclassified Mycobacterium palauense and Mycobacterium grossiae as Mycolicibacterium palauense comb. nov. and Mycolicibacterium grossiae comb. nov., respectively.

Secondary metabolites from the Actinomadura sp. and their cytotoxic activity.

Actinomadura sp., which is usually found in muddy habitats, produces various secondary metabolites with biological activities. In this study, five new compounds named formosensin A (1), formosensin B (2), oxanthroquinone-3-O-α-d-mannose (8), oxanthromicin A (9), and oxanthromicin B (10) were isolated from the culture of Actinomadura sp. together with five known compounds (3-7). Their structures were elucidated by extensive spectroscopic methods including NMR and MS. In particular, the absolute configurations of compounds 1 and 2 were determined using computational methods. Moreover, compounds 1-2 and 8-10 were screened for cytotoxic activity using a panel of human tumor cell lines. Compound 9 induced significant cytotoxicity in five human tumor cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW480) with IC50 values of 8.7, 17.5, 15.0, 17.8, and 14.6 µM, respectively. These findings suggested that compound 9 could provide therapeutic benefits in the treatment of tumor-related diseases.

Chryseobacterium luquanense sp. nov., a casein-hydrolysing bacterium from the Jiaozi Mountain in Yunnan, PR China.

Strain KC 927T was isolated during an investigation of the soil bacteria diversity on Jiaozi Mountain, central Yunnan, Southwest China. The strain was Gram-stain-negative, rod-shaped, non-motile, oxidase-negative, catalase-positive and aerobic. Results of 16S rRNA gene alignment and phylogenetic analysis indicated that strain KC 927T was a member of the genus Chryseobacterium and closely related to Chryseobacterium caseinilyticum GCR10T (98.4%), Chryseobacterium piscicola DSM 21068T (98.3 %) and 'Chryseobacterium formosus' CCTCC AB 2015118T (97.9 %). With a genome size of 4 348 708 bp, strain KC 927T had 33.5 mol% DNA G+C content and contained 4012 protein-coding genes and 77 RNA genes. The average nucleotide identity and digital DNA-DNA hybridization values between strain KC 927T and C. caseinilyticum GCR10T, C. piscicola DSM 21068T and 'C. formosus' CCTCC AB 2015118T were 80.1, 79.6 and 90.7 %, and 25.5, 23.6 and 42.0 %, respectively. The main polar lipid of strain KC 927T was phosphatidylethanolamine and the respiratory quinone was MK-6. The major fatty acids (≥10 %) were iso-C15 : 0, iso-C17 : 1 ω9c and iso-C17 : 0 3-OH. Evidence from phenotypic, phylogenetic and chemotaxonomic analyses support that strain KC 927T represents a new species of the genus Chryseobacterium, for which the name Chryseobacterium luquanense sp. nov. is proposed. The type strain is KC 927T (=CGMCC 1.18760T=JCM 35707T).

Chromosome-level Dinobdella ferox genome provided a molecular model for its specific parasitism.

BACKGROUND: Dinobdella ferox is the most frequently reported leech species parasitizing the mammalian nasal cavity. However, the molecular mechanism of this special parasitic behavior has remained largely unknown. METHODS: PacBio long-read sequencing, next-generation sequencing (NGS), and Hi-C sequencing were employed in this study to generate a novel genome of D. ferox, which was annotated with strong certainty using bioinformatics methods. The phylogenetic and genomic alterations of D. ferox were then studied extensively alongside the genomes of other closely related species. The obligatory parasitism mechanism of D. ferox was investigated using RNA-seq and proteomics data. RESULTS: PacBio long-read sequencing and NGS yielded an assembly of 228 Mb and contig N50 of 2.16 Mb. Along Hi-C sequencing, 96% of the sequences were anchored to nine linkage groups and a high-quality chromosome-level genome was generated. The completed genome included 19,242 protein-coding genes. For elucidating the molecular mechanism of nasal parasitism, transcriptome data were acquired from the digestive tract and front/rear ends of D. ferox. Examining secretory proteins in D. ferox saliva helped to identify intimate connections between these proteins and membrane proteins in nasal epithelial cells. These interacting proteins played important roles in extracellular matrix (ECM)-receptor interaction, tight junction, focal adhesion, and adherens junction. The interaction between D. ferox and mammalian nasal epithelial cells included three major steps of pattern recognition, mucin connection and breakdown, and repair of ECM. The remodeling of ECM between epithelial cells of the nasal mucosa and epithelial cells of D. ferox may produce a stable adhesion environment for parasitism. CONCLUSIONS: Our study represents the first-ever attempt to propose a molecular model for specific parasitism. This molecular model may serve as a practical reference for parasitism models of other species and a theoretical foundation for a molecular process of parasitism.

Ethanol mediates the interaction between Caenorhabditis elegans and the nematophagous fungus Purpureocillium lavendulum.

Accurately recognizing pathogens by the host is vital for initiating appropriate immune response against infecting microorganisms. Caenorhabditis elegans has no known receptor to recognize pathogen-associated molecular pattern. However, recent studies showed that nematodes have a strong specificity for transcriptomes infected by different pathogens, indicating that they can identify different pathogenic microorganisms. However, the mechanism(s) for such specificity remains largely unknown. In this study, we showed that the nematophagous fungus Purpureocillium lavendulum can infect the intestinal tract of the nematode C. elegans and the infection led to the accumulation of reactive oxygen species (ROS) in the infected intestinal tract, which suppressed fungal growth. Co-transcriptional analysis revealed that fungal genes related to anaerobic respiration and ethanol production were up-regulated during infection. Meanwhile, the ethanol dehydrogenase Sodh-1 in C. elegans was also up-regulated. Together, these results suggested that the infecting fungi encounter hypoxia stress in the nematode gut and that ethanol may play a role in the host-pathogen interaction. Ethanol production in vitro during fungal cultivation in hypoxia conditions was confirmed by gas chromatography-mass spectrometry. Direct treatment of C. elegans with ethanol elevated the sodh-1 expression and ROS accumulation while repressing a series of immunity genes that were also repressed during fungal infection. Mutation of sodh-1 in C. elegans blocked ROS accumulation and increased the nematode's susceptibility to fungal infection. Our study revealed a new recognition and antifungal mechanism in C. elegans. The novel mechanism of ethanol-mediated interaction between the fungus and nematode provides new insights into fungal pathogenesis and for developing alternative biocontrol of pathogenic nematodes by nematophagous fungi. IMPORTANCE Nematodes are among the most abundant animals on our planet. Many of them are parasites in animals and plants and cause human and animal health problems as well as agricultural losses. Studying the interaction of nematodes and their microbial pathogens is of great importance for the biocontrol of animal and plant parasitic nematodes. In this study, we found that the model nematode Caenorhabditis elegans can recognize its fungal pathogen, the nematophagous fungus Purpureocillium lavendulum, through fungal-produced ethanol. Then the nematode elevated the reactive oxygen species production in the gut to inhibit fungal growth in an ethanol dehydrogenase-dependent manner. With this mechanism, novel biocontrol strategies may be developed targeting the ethanol receptor or metabolic pathway of nematodes. Meanwhile, as a volatile organic compound, ethanol should be taken seriously as a vector molecule in the microbial-host interaction in nature.

Characterization of the complete mitochondrial genome of the nematode-trapping fungus Drechslerella dactyloides.

The complete mitochondrial genome of Drechslerella dactyloides was characterized in this study. This mitogenome is a closed circular molecule of 246860 bp in length with a GC content of 26.16%, including 87 predicted protein-coding genes, 29 transfer RNA genes, and two rRNA gens. Phylogenetic analyses based on concatenated amino acid sequences at 14 conserved mitochondrial protein-coding genes showed that D. dactyloides was closely related to Dactylellina haptotyla.

Streptothiazolidine B, a new cytotoxic alkaloid produced by Streptomyces violaceoruber.

A new cytotoxic alkaloid, named streptothiazolidine B (1), together with three known compounds (2-4), were isolated from Streptomyces violaceoruber. The structure of the undescribed compound was established using 1D and 2D NMR, and HRESIMS. Streptothiazolidine B was isolated and identified as an amide alkaloid with a unique thiazolidine side chain and its absolute configuration was determined by a combination of NOESY experiment and ECD analysis. Streptothiazolidine B exhibited significant cytotoxic activities against two human tumor cell lines, Li-7 and A2780, with IC50 values of 7.8, and 9.1 µM. Meanwhile, compound 4 showed obvious cytotoxic activities against four human tumor cell lines, THP-1, HT29, Li-7 and A2780, with IC50 values ranging from 3.1 to 10.2 µM.

Streptomyces plumbidurans sp. nov., a Pb2+-tolerant actinomycete.

A novel actinobacterium, designated KC 17012T, was isolated from lead zinc tailings collected from Lanping, Yunnan, PR China. Comparative 16S rRNA gene sequencing showed that KC 17012T belonged to the genus Streptomyces and was most closely related to the type strains of Streptomyces neyagawaensis (98.34%), Streptomyces panaciradicis (98.34%) and Streptomyces heilongjiangensis (98.27%). Phylogenetic tree analysis revealed strain KC 17012T formed a distinct clade. The genome size was 8.64 Mbp with a DNA G+C content of 70.8%. Digital DNA-DNA hybridization and average nucleotide identity values between the genome sequence of strain KC 17012T and those of S. neyagawaensis JCM 4796T (25.3 and 81.5 %) and S. panaciradicis NBRC 109811T (30.1 and 85.7 %) were below the thresholds of 70 and 96% for prokaryotic conspecific assignation. The strain formed long straight aerial hyphae which generated regular short rod spores with spiny surfaces. Growth occurred at 10-45 °C, pH 6-8 and with 0-9 % NaCl (w/v). Strain KC 17012T contained ll-diaminopimelic acid and the major whole-cell hydrolysates included glucose, mannose and ribose. The menaquinones were MK-9(H4), MK-9(H6) and MK-9(H8). The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, one unidentified lipid and one unidentified phospholipid. On the basis of the results of a polyphasic taxonomic study, it is concluded that KC 17012T represents a novel species of the genus Streptomyces, for which the name Streptomyces plumbidurans sp. nov., is proposed. The type strain is KC 17012T (CGMCC 4.7704T=JCM 35204T).

Siccirubricoccus soli sp. nov., a novel bacterial species isolated from Jiaozi Mountain soil.

An isolate of Gram-stain-negative and strictly aerobic bacterium, designated KC 17139T, was isolated from Jiaozi Mountain sample in Yunnan, China. Cells were non-motile cocci to oval, catalase-positive and oxidase-positive. Growth occurred at 0-7% NaCl (w/v; optimum, 0%), pH 6.0-8.0 (optimum, pH 7.0) and 15-45 °C (optimum, 28-37 °C). The polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC) and four unidentified aminolipids (UALs). Strain KC 17139T contained summed feature 8 (comprising C18:1 ω7c and/or C18:1 ω6c), C18:1 2OH and C16:0 as major cellular fatty acids (> 5%) and ubiquinone-10 as the sole isoprenoid quinone. The 16S rRNA gene sequence analysis indicated that strain KC 17139T shared highest similarities with Siccirubricoccus phaeus 1-3T (96.7%) and Siccirubricoccus deserti SYSU D8009T (95.0%). Strain KC 17139T clustered with the two Siccirubricoccus type strains, but formed a separate branch in both 16S rRNA gene and genome-scale phylogenetic dendrograms. The genomic DNA G + C content of strain KC 17139T was 71.2%. Genomic comparisons between strain KC 17139T and its close relatives showed the highest digital DNA-DNA hybridisation to S. phaeus (35.5%), highest average nucleotide identity to S. phaeus (88.2%), indicating that strain KC 17139T represents a novel species. On the basis of results of phenotypic, chemotaxonomic and molecular analysis, we report a new bacterium strain KC 17139T belonged to genus Siccirubricoccus, for which the name Siccirubricoccus soli sp. nov. is proposed. The type strain is KC 17139T (= CGMCC 1.18756T = JCM 35132T).

Characterization of the complete mitochondrial genome of the nematophagous fungus Purpureocillium lavendulum.

The complete mitochondrial genome of Purpureocillium lavendulum was characterized in this study. This mitogenome is a closed circular molecule of 23,567 bp in length with a GC content of 28.46%, including 15 protein-coding genes, 25 transfer RNA genes, 2 ribosomal RNA genes. Phylogenetic analyses based on sequences at the 14 concatenated mitochondrial protein-coding genes showed that P. lavendulum was closely related to Hirsutella minnesotensis.

Class IV Lasso Peptides Synergistically Induce Proliferation of Cancer Cells and Sensitize Them to Doxorubicin.

Heterologous expression of a biosynthesis gene cluster from Amycolatopsis sp. resulted in the discovery of two unique class IV lasso peptides, felipeptins A1 and A2. A mixture of felipeptins stimulated proliferation of cancer cells, while having no such effect on the normal cells. Detailed investigation revealed, that pre-treatment of cancer cells with a mixture of felipeptins resulted in downregulation of the tumor suppressor Rb, making the cancer cells to proliferate faster. Pre-treatment with felipeptins made cancer cells considerably more sensitive to the anticancer agent doxorubicin and re-sensitized doxorubicin-resistant cells to this drug. Structural characterization and binding experiments showed an interaction between felipeptins resulting in complex formation, which explains their synergistic effect. This discovery may open an alternative avenue in cancer treatment, helping to eliminate quiescent cells that often lead to cancer relapse.

Functional Characterization of Core Regulatory Genes Involved in Sporulation of the Nematophagous Fungus Purpureocillium lavendulum.

The nematophagous fungus Purpureocillium lavendulum is a natural enemy of plant-parasitic nematodes, which cause severe economic losses in agriculture worldwide. The production of asexual spores (conidia) in P. lavendulum is crucial for its biocontrol activity against nematodes. In this study, we characterized the core regulatory genes involved in conidiation of P. lavendulum at the molecular level. The central regulatory pathway is composed of three genes, P. lavendulumbrlA (PlbrlA), PlabaA, and PlwetA, which regulate the early, middle, and late stages of asexual development, respectively. The deletion of PlbrlA completely inhibited conidiation, with only conidiophore stalks produced. PlAbaA determines the differentiation of conidia from phialides. The deletion of PlwetA affected many phenotypes related to conidial maturation, including abscission of conidia from conidium strings, thickening of the cell wall layers, vacuole generation inside the cytoplasm, production of trehalose, tolerance to heat shock, etc. Comparative analyses showed that the upstream regulators of the core regulatory pathway of conidiation, especially the "fluffy" genes, were different from those in Aspergillus Besides their roles in conidiation, the central regulators also influence the production of secondary metabolites, such as the leucinostatins, in P. lavendulum Our study revealed a set of essential genes controlling conidiation in P. lavendulum and provided a framework for further molecular genetic studies on fungus-nematode interactions and for the biocontrol of plant-parasitic nematodes.IMPORTANCE Plant-parasitic nematodes cause serious damage to crops throughout the world. Purpureocillium lavendulum is a nematophagous fungus which is a natural enemy of nematodes and a potential biocontrol agent against plant-parasitic nematodes. The conidia play an important role during infection of nematodes. In this study, we identified and characterized genes involved in regulating asexual development of P. lavendulum We found that these genes not only regulate conidiation but also influence secondary-metabolite production. This work provides a basis for future studies of fungus-nematode interactions and nematode biocontrol.

An efficient gene disruption system for the nematophagous fungus Purpureocillium lavendulum.

The fungus Purpureocillium lavendulum (formally Paecilomyces lilacinus) is a natural enemy of insects and plant-parasitic nematodes, and has been used as an important bio-control agent against agricultural pests all over the world. In order to understand the genetic mechanisms governing its biocontrol efficiency and other biological processes, an effective gene disruption system is needed. Here we report the development of an efficient system which integrates selective markers that differ from Purpureocillium lilacinum, a one-step construction method for gene knockout plasmids, and a ku80 knockout strain for efficient homologous recombination. With this system, we effectively disrupted the transcription factors in the central regulation pathway of sporulation and a serine protease which were contributed to nematode infection, demonstrating this system as an efficient gene disrupting system for further characterization of genes involved in the development and pathogenesis of this fungus.

Actinorectispora metalli sp. nov., a novel actinomycete isolated from a mine and emended description of the genus Actinorectispora.

A novel actinomycete, designated strain KC 198T, was isolated from rare earth mine. The results of analysis of the 16S rRNA gene sequence indicated that KC 198T was most closely related to Actinorectisporaindica YIM 75728T (98.4 %). Aerial hyphae differentiated into long, straight chains of cylindrical spores. Growth was observed at 10-45 °C (optimum 28 °C), with 0-10 % (w/v) NaCl (optimum, in the absence of NaCl) and at pH 6.0-8.0 (optimum pH 7.0). KC 198T possessed MK-9(H4) as the predominant respiratory quinone and a minor amount of MK-10(H4). Polar lipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. Three unidentified lipids were also detected. The main cellular fatty acids were iso-C16 : 0 (30.9 %), iso-C16 : 1H (22.9 %) and iso-C15 : 0 (14.8 %). The genomic DNA G+C content was 66.8 mol%. On the basis of the phenotypic and genotypic characteristics, we propose that strain KC 198T represents a novel species of the genus Actinorectispora. The name Actinorectispora metalli sp. nov. is, therefore, proposed for the novel species with the type strain KC 198T (=CCTCC AA 2015043T=KCTC 39718T). The description of the genus Actinorectispora has also been emended.

Kibdelosporangium metalli sp. nov., isolated from a rare earth mine.

A Gram-stain-positive, oxidase-negative, catalase-positive isolate forming sporangium-like globular bodies, isolated from the rare earth mine of Bayan Obo in China and designated strain KC 266T, was subjected to a comprehensive taxonomic study. Comparative 16S rRNA gene sequence analysis revealed that strain KC 266T represented a novel lineage within the genus Kibdelosporangium and showed highest 16S rRNA gene similarities to Kibdelosporangiumphilippinense (98.5 %), Kibdelosporangiumaridum subsp. largum (98.2 %), Kibdelosporangiumaridum subsp. aridum (98.2 %) and Kibdelosporangiumphytohabitans (98.0 %). The DNA-DNA relatedness between strain KC 266T and the four species of the genus Kibdelosporangium was less than 60 %. The DNA G+C content of strain KC 266T was 67.9 mol%. The quinone system consisted of major amounts of MK-9(H4) and MK-9(H2), minor amounts of MK-8(H2) and traces of MK-10(H4). The diamino acid of the peptidoglycan was meso-diaminopimelic acid. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, two unknown phospholipids and one unidentified aminophospholipid. The major cellular fatty acids were iso-C16 : 0, C17 : 1 ω6c, iso-C15 : 0 and iso-C14 : 0. Physiological traits as well as unique traits of the polar lipid profile and the fatty acid pattern distinguished strain KC 266T from the most closely related species. All these results indicate that strain KC 266T represents a novel species of the genus Kibdelosporangium, for which the name Kibdelosporangium metalli sp. nov. is proposed. The type strain is KC 266T (=KCTC 39719T=CCTCC AA 2016002T).

Allokutzneria multivorans sp. nov., an actinomycete isolated from soil.

An actinomycete with well-branched mycelia, designated strain YIM 120521(T), was isolated from soil collected from the banks of the Nujiang River, Yunnan Province, south-west China. Both aerial and substrate mycelia were white and non-pigmented. Growth was observed at 4-40 °C (optimum 28 °C), pH 6.0-9.0 (optimum 7.0) and in 0-4 % (w/v) NaCl (optimum 0 %). Analysis of the 16S rRNA gene sequence revealed that strain YIM 120521(T) belongs to the genus Allokutzneria with the highest sequence similarity to Allokutzneria albata DSM 44149(T) (98.4 %). However, the mean DNA-DNA relatedness value between the two strains was below 70 %. Chemotaxonomic characteristics supported the inclusion of strain YIM 120521(T) in the genus Allokutzneria, with rhamnose, arabinose, glucose, galactose and mannose as the whole-cell sugars, meso-diaminopimelic acid as the cell-wall diamino acid and MK-9(H4) as the predominant menaquinone. On the basis of physiological, biochemical and chemotaxonomic characteristics, strain YIM 120521(T) is considered to represent a novel species of the genus Allokutzneria, for which the name Allokutzneria multivorans sp. nov. is proposed. The type strain is YIM 120521(T) ( = JCM 17342(T) = DSM 45532(T)).

Structure elucidation of four prenylindole derivatives from Streptomyces sp. isolated from Ailuropoda melanoleuca feces.

Four new prenylindole derivatives, (R)-6-(2,3-dihydroxy-3-methylbutyl)indole (1), (R)-6-(2,3-dihydroxy-3-methylbutyl)indolin-2-one (2), and an unseparated mixture of (Z)-6-(4-hydroxy-3-methylbut-2-en-1-yl)indolin-2-one (3a) and (E)-6-(4-hydroxy-3-methylbut-2-en-1-yl)indolin-2-one (3b) with a ratio of 3 : 2, were isolated from the culture broth of a streptomycete isolated from Ailuropoda melanoleuca feces. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic techniques. The absolute configuration of 1 was determined by Mosher's method.

Effect of heavy metal-solubilizing microorganisms on zinc and cadmium extractions from heavy metal contaminated soil with Tricholoma lobynsis.

The macrofungus, Tricholoma lobynsis, was chosen to remedy Zn-Cd-Pb contaminated soil. To enhance its metal-extracting efficiency, two heavy metal resistant microbes M6 and K1 were applied owing to their excellent abilities to solubilize heavy metal salts. The two isolated microbial strains could also produce indole acetic acid (IAA), siderophore and solubilize inorganic phosphate, but neither of them showed 1-aminocyclopropane-1-carboxylate deaminase activity. The strains M6 and K1 were identified as Serratia marcescens and Rhodotorula mucilaginosa based on 16S rDNA and ITS sequence analysis respectively. Pot experiment showed that spraying to T. lobynsis-inoculated soil with M6 and K1 respectively could increase total Cd accumulations of this mushroom by 216 and 61%, and Zn by 153 and 49% compared to the uninoculated control. Pb accumulation however, was too low (<1 mg kg(-1)) to be determined. The results illustrated that special microbes and macrofungi can work together to remedy polluted soil as plant and plant growth promoting microbes do, probably because of excellent metal-accumulating abilities of macrofungi and IAA-siderophore production, phosphate solubilization abilities of the assisted-microbes. This kind of macrofungi-microbe interaction can be developed into a novel bioremediation strategy.

Lead and cadmium-induced oxidative stress impacting mycelial growth of Oudemansiella radicata in liquid medium alleviated by microbial siderophores.

In this study, the effects of siderophores produced by six bacteria on mycelium growth, Cd and Pb accumulation, lipid peroxidation, protein content and antioxidant enzyme in Oudemansiella radicata were investigated in Cd and Pb-containing liquid medium. The results showed that inoculation with siderophore-containing filtrates (SCF) partly enhanced the growth of O. radicata after 15 days, with 0.8-32.4% biomass increase for Cd and 0.7-20.8% for Pb compared to control(s), which lacked siderophore. The maximum enhancement for accumulation were found to be confined to Bacillus sp. FFQ2(s) (26.5%) for Cd and Pseudomonas sp. CY63(s) (158.9%) for Pb. A significant decrease in MDA content indicated that lipid peroxidation in O. radicata was alleviated by siderophores. Besides, antioxidant enzyme SOD and POD activities also displayed obviously decrease in SCF-treated mycelium compared to control(s) treatment, while CAT activity did not present significant change. Protein level in O. radicata treated by SCF increased from 0.3 to 138.0% for Cd and from 10.9 to 107.1% for Pb compared to control(s). Therefore, the present work suggests that microbial siderophores can reduce the toxicity of metals to mycelium and then alleviate heavy metals-inducing oxidative stress in O. radicata.