Talaromyces halophytorum sp. nov. Isolated from Roots of Limonium tetragonum in Korea.

Talaromyces halophytorum sp. nov. was isolated from the roots of halophyte Limonium tetragonum collected from Seocheon-gun, Korea in November 2015. It showed a slow growth on yeast extract sucrose agar at 25 °C, no growth at 4 °C or 37 °C and produced smooth-walled and globose to sub-globose conidia. T. halophytorum is phylogenetically distinct from the other reported Talaromyces species of section Trachyspermi based on multi-locus sequence typing results using partial fragments of ß-tubulin, calmodulin, ITS, and RNA polymerase II genes.

Pulveribacter suum gen. nov., sp. nov., isolated from a pig farm dust collector.

An aerobic, Gram-stain-negative, polar-flagellated, rod-shaped bacterium, designated as SC2-7T, was isolated from the dust collector at a pig farm located in Wanju-gun, Jeollabuk-do, Republic of Korea. Growth occurred at 10-37 °C (optimum, 28-30 °C), pH 6.0-10.0 (optimum, 7.0-8.0) and in the presence of 0-3 % (w/v) NaCl (optimum, 0 %) on Reasoner's 2A medium. The phylogenetic tree based on the 16S rRNA gene sequences revealed that strain SC2-7T was a member of the family Comamonadaceae, forming a robust cluster with the genera Alicycliphilus, Oryzisolibacter and Melaminivora. The 16S rRNA gene sequences of strain SC2-7T showed the highest sequence similarities to Alicycliphilus denitrificans K601T (97.2 %), Oryzisolibacter propanilivorax EPL6T (97.0 %), Melaminivora alkalimesophila CY1T (96.9 %), Diaphorobacter polyhydroxybutyrativorans SL-205T (96.6 %), Diaphorobacter nitroreducens NA10BT (96.6 %) and Melaminivora jejuensis KBB12T (96.5 %). The tree based on the gyrA gene sequences also showed that strain SC2-7T fell into a phylogenetic position similar to that based on the 16S rRNA gene sequences. The polar lipids present were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, an unidentified aminolipid and an unidentified phospholipid. The predominant quinone was ubiquione-8. The major fatty acids were summed feature 3 (including C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and summed feature 8 (including C18 : 1ω6c and/or C18 : 1ω7c). The genomic DNA G+C content was 69.1 mol%. On the basis of the phenotypic, phylogenetic and chemotaxonomic data presented here, strain SC2-7T represents a novel species of a new genus, for which the name Pulveribacter suum gen. nov., sp. nov., is proposed. The type strain of Pulveribacter suum is SC2-7T (=KACC 19309T=NBRC 113102T).

Diversity of Aspergillus, Penicillium, and Talaromyces Species Isolated from Freshwater Environments in Korea.

In order to elucidate the fungal diversity and community structure in freshwater environments, numerous fungal strains were isolated from freshwater, submerged soils, twigs, dead insects, etc. Among them, the present study has focused specifically on Aspergillus, Penicillium, and Talaromyces species, which produce diverse useful metabolites in general. Twelve strains of Aspergillus isolated were identified as A. japonicus (n = 5), A. tubingensis (3), A. niger (2), and A. flavus (2), 10 strains of which belong to Aspergillus section Nigri, named black Aspergillus. Eight strains of Penicillium were identified as P. brasilianim (n = 3), P. oxalicum (2), P. crustosum (1), P. expansum (1), and P. piscarium (1). Two different strains of Talaromyces were identified as T. pinophilus and T. versatilis. Thus far, Penicillium piscarium and Talaromyces versatilis have been unrecorded in Korea, for which we provide detailed morphological and molecular characteristics.

Complete mitochondrial genome sequence of a xerophilic fungus, Aspergillus pseudoglaucus.

Aspergillus pseudoglaucus is a xerophilic filamentous fungus which can produce various secondary metabolites. Here, we reported the complete mitochondrial genome sequence of A. pseudoglaucus isolated from Meju, a soybean brick in Korea. Its mitochondrial genome was successfully assembled from raw reads sequenced using MiSeq by Velvet and SOAPGapCloser. Total length of the mitochondrial genome is 53,882 bp, which is third longest among known Aspergillus mitochondrial genomes and encoded 58 genes (30 protein-coding genes including hypothetical ORFs, two rRNAs, and 26 tRNAs). Nucleotide sequence of coding regions takes over 66.6% and overall GC content is 27.8%. Phylogenetic trees present that A. pseudoglaucus is located outside of section Nidulantes. Additional researches will be required for clarifying phylogenetic position of section Aspergillus.

Characteristics of a Regulator of G-Protein Signaling (RGS) rgsC in Aspergillus fumigatus.

The regulator of G-protein signaling (RGS) proteins have a conserved RGS domain that facilitates the intrinsic GTPase activity of an activated Gα subunit of heterotrimeric G protein, thereby attenuating signal transduction. Among six predicted RGS proteins in the opportunistic human pathogenic fungus Aspergillus fumigatus, only three (FlbA, GprK, and Rax1) have been studied. The unexplored RgsC composed of the Phox-associated (PXA), RGS, Phox homology (PX), and Nexin_C superfamily domains is highly conserved in many ascomycete fungi, suggesting a crucial role of RgsC in fungal biology. To address this, we have investigated functions of the rgsC gene. The deletion (Δ) of rgsC causes impaired vegetative growth and asexual development coupled with reduced expression of key developmental regulators. Moreover, ΔrgsC results in accelerated and elevated conidial germination regardless of the presence or absence of an external carbon source. Furthermore, ΔrgsC causes reduced conidial tolerance to oxidative stress. In addition, activities and expression of catalases and superoxide dismutases (SODs) are severely decreased in the ΔrgsC mutant. The deletion of rgsC results in a slight reduction in conidial tolerance to cell wall damaging agents, yet significantly lowered mRNA levels of cell wall integrity/biogenesis transcription factors, indicating that RgsC may function in proper activation of cell wall stress response. The ΔrgsC mutant exhibits defective gliotoxin (GT) production and decreased virulence in the wax moth larvae, Galleria mellonella. Transcriptomic studies reveal that a majority of transporters is down-regulated by ΔrgsC and growth of the ΔrgsC mutant is reduced on inorganic and simple nitrogen medium, suggesting that RgsC may function in external nitrogen source sensing and/or transport. In summary, RgsC is necessary for proper growth, development, stress response, GT production, and external nutrients sensing.

Aspergillus fumigatus spore proteomics and genetics reveal that VeA represses DefA-mediated DNA damage response.

Aspergillus fumigatus reproduces and infects host by forming a high number of small asexual spores (conidia). The velvet proteins are global transcriptional regulators governing the complex process of conidiogenesis in this fungus. Here, to further understand the velvet-mediated regulation, we carried out comparative proteomic analyses of conidia of wild type (WT) and three velvet mutants (ΔveA, ΔvelB and ΔvosA). Cluster analysis of 184 protein spots showing at least 1.5-fold differential accumulation between WT and mutants reveal the clustering of WT- ΔveA and ΔvelB-ΔvosA. Among 43 proteins identified by Nano-LC-ESI-MS/MS, 23 including several heat shock proteins showed more than two-fold reduction in both the ∆velB and ∆vosA conidia. On the contrary, three proteins exhibited more than five-fold increase in ∆veA only, including the putative RNA polymerase II degradation factor DefA. The deletion of defA resulted in a reduced number of conidia and restricted colony growth. In addition, the defA deletion mutant conidia showed hypersensitivity against the DNA damaging agents NQO and MMS, while the ΔveA mutant conidia were more resistant against to NQO. Taken together, we propose that VeA controls protein level of DefA in conidia, which are dormant and equipped with multiple layers of protection against environmental cues.