Journal of Microbiology

Review

Manganese Transporter Proteins in Salmonella enterica serovar Typhimurium: Nakyeong Ha , Eun-Jin Lee; J. Microbiol. 2023;61(3):289-296. Published online March 2, 2023; DOI: https://doi.org/10.1007/s12275-023-00027-7

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Abstract: The metal cofactors are essential for the function of many enzymes. The host restricts the metal acquisition of pathogens for their immunity and the pathogens have evolved many ways to obtain metal ions for their survival and growth. Salmonella enterica serovar Typhimurium also needs several metal cofactors for its survival, and manganese has been found to contribute to Salmonella pathogenesis. Manganese helps Salmonella withstand oxidative and nitrosative stresses. In addition, manganese affects glycolysis and the reductive TCA, which leads to the inhibition of energetic and biosynthetic metabolism. Therefore, manganese homeostasis is crucial for full virulence of Salmonella. Here, we summarize the current information about three importers and two exporters of manganese that have been identified in Salmonella. MntH, SitABCD, and ZupT have been shown to participate in manganese uptake. mntH and sitABCD are upregulated by low manganese concentration, oxidative stress, and host NRAMP1 level. mntH also contains a Mn2+- dependent riboswitch in its 5′ UTR. Regulation of zupT expression requires further investigation. MntP and YiiP have been identified as manganese efflux proteins. mntP is transcr!ptionally activated by MntR at high manganese levels and repressed its activity by MntS at low manganese levels. Regulation of yiiP requires further analysis, but it has been shown that yiiP expression is not dependent on MntS. Besides these five transporters, there might be additional transporters that need to be identified.

Journal Articles

Discovery of novel glycoside hydrolases from C-glycoside-degrading bacteria using sequence similarity network analysis: Bin Wei , Ya-Kun Wang , Jin-Biao Yu , Si-Jia Wang , Yan-Lei Yu , Xue-Wei Xu , Hong Wang; J. Microbiol. 2021;59(10):931-940. Published online September 23, 2021; DOI: https://doi.org/10.1007/s12275-021-1292-4

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Abstract: C-Glycosides are an important type of natural product with significant bioactivities, and the C-glycosidic bonds of C-glycosides can be cleaved by several intestinal bacteria, as exemplified by the human faeces-derived puerarin-degrading bacterium Dorea strain PUE. However, glycoside hydrolases in these bacteria, which may be involved in the C-glycosidic bond cleavage of C-glycosides, remain largely unknown. In this study, the genomes of the closest phylogenetic neighbours of five puerarin-degrading intestinal bacteria (including Dorea strain PUE) were retrieved, and the protein-coding genes in the genomes were subjected to sequence similarity network (SSN) analysis. Only four clusters of genes were annotated as glycoside hydrolases and observed in the genome of D. longicatena DSM 13814T (the closest phylogenetic neighbour of Dorea strain PUE); therefore, genes from D. longicatena DSM 13814T belonging to these clusters were selected to overexpress recombinant proteins (CG1, CG2, CG3, and CG4) in Escherichia coli BL21(DE3). In vitro assays indicated that CG4 efficiently cleaved the O-glycosidic bond of daidzin and showed moderate β-D-glucosidase and β-D-xylosidase activity. CG2 showed weak activity in hydrolyzing daidzin and pNP- β-D-fucopyranoside, while CG3 was identified as a highly selective and efficient α-glycosidase. Interestingly, CG3 and CG4 could be selectively inhibited by daidzein, explaining their different performance in kinetic studies. Molecular docking studies predicted the molecular determinants of CG2, CG3, and CG4 in substrate selectivity and inhibition propensity. The present study identified three novel and distinctive glycoside hydrolases, highlighting the potential of SSN in the discovery of novel enzymes from genomic data.

Mitochondrial genome and diverse inheritance patterns in Pleurotus pulmonarius: Li-Yun Ye+ , You-Jin Deng+ , Irum Mukhtar , Guo-Liang Meng , Yan-Jiao Song , Bing Cheng , Jin-bing Hao , Xiao-Ping Wu; J. Microbiol. 2020;58(2):142-152. Published online January 29, 2020; DOI: https://doi.org/10.1007/s12275-020-9318-x

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Abstract: Pleurotus pulmonarius, a member of the Pleurotaceae family in Basidiomycota, is an edible, economically important mushroom in most Asian countries. In this study, the complete mitochondrial genomes (mtDNA) of three P. pulmonarius strains – two monokaryotic commercial (J1-13 and ZA3) and one wild (X1-15) – were sequenced and analyzed. In ZA3 and X1-15, the mtDNA molecule was found to be a single circle of 68,305 bp and 73,435 bp, respectively. Both strains contain 14 core protein-coding genes and two ribosomal RNA (rRNA) subunit genes. The ZA3 strain has 22 transfer RNA (tRNA) genes and nine introns: eight in cytochrome c oxidase subunit 1 (cox1), and one in the rRNA large subunit (rnl). Monokaryotic J1-13 and ZA3 mtDNAs were found to be similar in their structure. However, the wild strain X1-15 contains 25 tRNA genes and only seven introns in cox1. Open reading frames (ORFs) of ZA3/J1-13 and X1-15 encode LAGLIDADG, ribosomal protein S3, and DNA polymerase II. In addition, mtDNA inheritance in J1-13, ZA3, and X1-15 was also studied.
Results
showed that the mtDNA inheritance pattern was uniparental and closely related to dikaryotic hyphal location with respect to the parent. Results also show that mtDNA inheritance is influenced by both the parental nuclear genome and mitogenome in the zone of contact between two compatible parents. In summary, this analysis provides valuable information and a basis for further studies to improve our understanding of the inheritance of fungal mtDNA.

Identification and characterization of a novel light-induced promoter for recombinant protein production in Pleurotus ostreatus: Chaomin Yin , Xiuzhi Fan , Kun Ma , Zheya Chen , Defang Shi , Fen Yao , Hong Gao , Aimin Ma; J. Microbiol. 2020;58(1):39-45. Published online November 4, 2019; DOI: https://doi.org/10.1007/s12275-020-9230-4

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Abstract: A lectin gene (plectin) with a high level of expression was previously identified by comparative transcriptome analysis of Pleurotus ostreatus. In this study, we cloned a 733-bp DNA fragment from the start codon of the plectin gene. Sequence analysis showed that the plectin promoter (Plp) region contained several eukaryotic transcription factor binding motifs, such as the TATA-box, four possible CAAT-box, light responsiveness motifs and MeJA-responsiveness motifs. To determine whether the Plp promoter was a light-regulated promoter, we constructed an expression vector with the fused egfp-hph fragment under the control of the Plp promoter and transformed P. ostreatus mycelia via Agrobacterium tumefaciens. PCR and Southern blot analyses confirmed the Plpegfp- hph fragment was integrated into the chromosomal DNA of transformants. qRT-PCR, egfp visualization, and intracellular egfp determination experiments showed the Plp promoter could be a light-induced promoter that may be suitable for P. ostreatus genetic engineering. This study lays the foundation for gene homologous expression in P. ostreatus.

Garden microbiomes of Apterostigma dentigerum and Apterostigma pilosum fungus-growing ants (Hymenoptera: Formicidae): Cely T. González , Kristin Saltonstall , Hermógenes Fernández-Marín; J. Microbiol. 2019;57(10):842-851. Published online August 3, 2019; DOI: https://doi.org/10.1007/s12275-019-8639-0

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Abstract: Fungus-growing ants share a complex symbiosis with microbes, including fungal mutualists, antibiotic-producing bacteria, and fungal pathogens. The bacterial communities associated with this symbiosis are poorly understood but likely play important roles in maintaining the health and function of fungal gardens. We studied bacterial communities in gardens of two Apterostigma species, A. dentigerum, and A. pilosum, using next-generation sequencing to evaluate differences between the two ant species, their veiled and no-veiled fungal garden types, and across three collection locations. We also compared different parts of nests to test for homogeneity within nests. Enterobacteriaceae dominated gardens of both species and common OTUs were shared across both species and nest types. However, differences in community diversity were detected between ant species, and in the communities of A. dentigerum veiled and no-veiled nests within sites. Apterostigma pilosum had a higher proportion of Phyllobacteriaceae and differed from A. dentigerum in the proportions of members of the order Clostridiales. Within A. dentigerum, nests with veiled and no-veiled fungus gardens had similar taxonomic profiles but differed in the relative abundance of some groups, with veiled gardens having more Rhodospirillaceae and Hyphomicrobiaceae, and no-veiled having more Xanthomonadaceae and certain genera in the Enterobacteriaceae C. However, bacterial communities in Apterostigma fungal gardens are highly conserved and resemble those of the nests of other attine ants with dominant taxa likely playing a role in biomass degradation and defense. Further work is required to understand and explain how bacterial community composition of fungus-growing nests is maintained.

Promising cellulolytic fungi isolates for rice straw degradation: Diana Catalina Pedraza-Zapata , Andrea Melissa Sánchez-Garibello , Balkys Quevedo-Hidalgo , Nubia Moreno-Sarmiento , Ivonne Gutiérrez-Rojas; J. Microbiol. 2017;55(9):711-719. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-6282-1

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Abstract: The objective of this study was to evaluate the potential of eight fungal isolates obtained from soils in rice crops for straw degradation in situ. From the initial eight isolates, Pleurotus ostreatus T1.1 and Penicillium sp. HC1 were selected for further characterization based on qualitative cellulolytic enzyme production and capacity to use rice straw as a sole carbon source. Subsequently, cellulolytic, xylanolytic, and lignolytic (Pleurotus ostreatus) activity on carboxymethyl cellulose, oat xylan, and rice straw with different nitrogen sources was evaluated. From the results obtained it was concluded both isolates are capable to produce enzymes necessary for rice straw degradation. However, their production is dependent upon carbon and nitrogen source. Last, it was established that Pleurotus ostreatus T1.1 and Penicillium sp. HC1 capability to colonize and mineralize rice straw, in mono-and co-culture, without affecting nitrogen soil content.

ZntR positively regulates T6SS4 expression in Yersinia pseudotuberculosis: Tietao Wang , Keqi Chen , Fen Gao , Yiwen Kang , Muhammad Tausif Chaudhry , Zhuo Wang , Yao Wang , Xihui Shen; J. Microbiol. 2017;55(6):448-456. Published online March 10, 2017; DOI: https://doi.org/10.1007/s12275-017-6540-2

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22 Citations

Abstract: The type VI secretion system (T6SS) is a widespread and versatile protein secretion system found in most Gram- negative bacteria. Studies of T6SS have mainly focused on its role in virulence toward host cells and inter-bacterial inter-actions, but studies have also shown that T6SS4 in Yersinia pseudotuberculosis participates in the acquisition of zinc ions to alleviate the accumulation of hydroxyl radicals induced by multiple stressors. Here, by comparing the gene expression patterns of wild-type and zntR mutant Y. pseudotubercu-losis cells using RNA-seq analysis, T6SS4 and 17 other bio-logical processes were found to be regulated by ZntR. T6SS4 was positively regulated by ZntR in Y. pseudotuberculosis, and further investigation demonstrated that ZntR regulates T6SS4 by directly binding to its promoter region. T6SS4 ex-pression is regulated by zinc via ZntR, which maintains in-tracellular zinc homeostasis and controls the concentration of reactive oxygen species to prevent bacterial death under oxidative stress. This study provides new insights into the regulation of T6SS4 by a zinc-dependent transcriptional regu-lator, and it provides a foundation for further investigation of the mechanism of zinc transport by T6SS.

Research Support, Non-U.S. Gov'ts

Species identity of Phellinus linteus (sanghuang) extensively used as a medicinal mushroom in Korea: Jae-Gu Han , Min-Woo Hyun , Chang Sun Kim , Jong Won Jo , Jae-Han Cho , Kang-Hyo Lee , Won-Sik Kong , Sang-Kuk Han , Junsang Oh , Gi-Ho Sung; J. Microbiol. 2016;54(4):290-295. Published online April 1, 2016; DOI: https://doi.org/10.1007/s12275-016-5520-2

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28 Citations

Abstract: Sanghuang is a medicinal mushroom that has gained particular attention in Korea. It has been extensively studied for the past few decades as a natural immune booster and cancer suppressor. Although the scientific name, Phellinus linteus, has been commonly used to refer to the sanghuang mushroom, the species identity of sanghuang has been called into question due to the ambiguity of its circumscription and the inadequacy of morphological distinctions within allied species. Because the species concept of sanghuang has been elucidated by recent molecular phylogenetic studies, it has become necessary to clarify the taxonomic positions of sanghuang strains extensively utilized in Korea. We conducted a phylogenetic analysis of 74 strains belonging to the P. linteus-baumii complex based on ITS nrDNA sequences. Parental stains of sanghuang varieties formally registered in the Korea Seed & Variety Service, including ASI 26046 (Corea sanghuang), 26114 (Boolro), and 26115 (HK 1-ho) were grouped with Sanghuangporus sanghuang instead of P. linteus in the inferred phylogeny.

Roles of RpoS in Yersinia pseudotuberculosis stress survival, motility, biofilm formation and type VI secretion system expression: Jingyuan Guan , Xiao Xiao , Shengjuan Xu , Fen Gao , Jianbo Wang , Tietao Wang , Yunhong Song , Junfeng Pan , Xihui Shen , Yao Wang; J. Microbiol. 2015;53(9):633-642. Published online August 27, 2015; DOI: https://doi.org/10.1007/s12275-015-0099-6

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47 Citations

Abstract: RpoS (σS), the stationary phase/stress σ factor, controls the expression of a large number of genes involved in cellular responses to a variety of stresses. However, the role of RpoS appears to differ in different bacteria. While RpoS is an important regulator of flagellum biosynthesis, it is associated with biofilm development in Edwardsiella tarda. Biofilms are dense communities formed by bacteria and are important for microbe survival under unfavorable conditions. The type VI secretion system (T6SS) discovered recently is reportedly associated with several phenotypes, ranging from biofilm formation to stress sensing. For example, Vibrio anguillarum T6SS was proposed to serve as a sensor for extracytoplasmic signals and modulates RpoS expression and stress response. In this study, we investigated the physiological roles of RpoS in Yersinia pseudotuberculosis, including bacterial survival under stress conditions, flagella formation, biofilm development and T6SS expression. We found that RpoS is important in resistance to multiple stressors–including H2O2, acid, osmotic and heat shock–in Y. pseudotuberculosis. In addition, our study showed that RpoS not only modulates the expression of T6SS but also regulates flagellum formation by positively controlling the flagellar master regulatory gene flhDC, and affects the formation of biofilm on Caenorhabditis elegans by regulating the synthesis of exopolysaccharides. Taken together, these results show that RpoS plays a central role in cell fitness under several adverse conditions in Y. pseudotuberculosis.

Distinct Patterns of Marine Bacterial Communities in the South and North Pacific Oceans: Sung-Suk Suh , Mirye Park , Jinik Hwang , Sukchan Lee , Youngjae Chung , Taek-Kyun Lee; J. Microbiol. 2014;52(10):834-841. Published online October 1, 2014; DOI: https://doi.org/10.1007/s12275-014-4287-6

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Abstract: The study of oceanic microbial communities is crucial for our understanding of the role of microbes in terms of biomass, diversity and ecosystem function. In this study, 16S rRNA gene tag pyrosequencing was used to investigate change in bacterial community structure between summer and winter water masses from Gosung Bay in the South Sea of Korea and Chuuk in Micronesia, located in the North and South Pacific Oceans, respectively. Summer and winter sampling from each water mass revealed highly diverse bacterial communities, containing ~900 Operational Taxonomic Units (OTUs). The microbial distribution and highly heterogeneous composition observed at both sampling sites were different from those of most macroorganisms. The bacterial communities in the seawater at both sites were most abundant in Proteobacteria during the summer in Gosung and in Bacterioidetes during the winter. The proportion of Cyanobacteria was higher in summer than in winter in Chuuk and similar in Gosung. Additionally, the microbial community during summer in Gosung was significantly different from other communities observed based on the unweighted UniFrac distance. These data suggest that in both oceanic areas sampled, the bacterial communities had distinct distribution patterns with spatially- and temporally-heterogeneous distributions.

Review

REVIEW] Perturbation of Pulmonary Immune Functions by Carbon Nanotubes and Susceptibility to Microbial Infection: Brent E. Walling , Gee W. Lau; J. Microbiol. 2014;52(3):227-234. Published online March 1, 2014; DOI: https://doi.org/10.1007/s12275-014-3695-y

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Abstract: Occupational and environmental pulmonary exposure to carbon nanotubes (CNT) is considered to be a health risk with a very low threshold of tolerance as determined by the United States Center for Disease Control. Immortalized airway epithelial cells exposed to CNTs show a diverse range of effects including reduced viability, impaired proliferation, and elevated reactive oxygen species generation. Additionally, CNTs inhibit internalization of targets in multiple macrophage cell lines. Mice and rats exposed to CNTs often develop pulmonary granulomas and fibrosis. Furthermore, CNTs have immunomodulatory properties in these animal models. CNTs themselves are proinflammatory and can exacerbate the allergic response. However, CNTs may also be immunosuppressive, both locally and systemically. Studies that examined the relationship of CNT exposure prior to pulmonary infection have reached different conclusions. In some cases, pre-exposure either had no effect or enhanced clearance of infections while other studies showed CNTs inhibited clearance. Interestingly, most studies exploring this relationship use pathogens which are not considered primary pulmonary pathogens. Moreover, harmony across studies is difficult as different types of CNTs have dissimilar biological effects. We used Pseudomonas aeruginosa as model pathogen to study how helical multi-walled carbon nanotubes (HCNTs) affected internalization and clearance of the pulmonary pathogen. The results showed that, although HCNTs can inhibit internalization through multiple processes, bacterial clearance was not altered, which was attributed to an enhanced inflammatory response caused by pre-exposure to HCNTs. We compare and contrast our findings in relation to other studies to gauge the modulation of pulmonary immune response by CNTs.

Research Support, Non-U.S. Gov'ts

TBC: A Clustering Algorithm Based on Prokaryotic Taxonomy: Jae-Hak Lee , Hana Yi , Yoon-Seong Jeon , Sungho Won , Jongsik Chun; J. Microbiol. 2012;50(2):181-185. Published online April 27, 2012; DOI: https://doi.org/10.1007/s12275-012-1214-6

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19 Citations

Abstract: High-throughput DNA sequencing technologies have revolutionized the study of microbial ecology. Massive sequencing of PCR amplicons of the 16S rRNA gene has been widely used to understand the microbial community structure of a variety of environmental samples. The resulting sequencing reads are clustered into operational taxonomic units that are then used to calculate various statistical indices that represent the degree of species diversity in a given sample. Several algorithms have been developed to perform this task, but they tend to produce different outcomes. Herein, we propose a novel sequence clustering algorithm, namely Taxonomy-Based Clustering (TBC). This algorithm incorporates the basic concept of prokaryotic taxonomy in which only comparisons to the type strain are made and used to form species while omitting full-scale multiple sequence alignment. The clustering quality of the proposed method was compared with those of MOTHUR, BLASTClust, ESPRITTree, CD-HIT, and UCLUST. A comprehensive comparison using three different experimental datasets produced by pyrosequencing demonstrated that the clustering obtained using TBC is comparable to those obtained using MOTHUR and ESPRIT-Tree and is computationally efficient. The program was written in JAVA and is available from http://sw. ezbiocloud.net/tbc.

Effect of Light and Reductones on Differentiation of Pleurotus ostreatus: Seung-Rock Lee , Woo-Jeong Joo , Yong-Un Baek , Inyoung Kim , Kee-Oh Chay , Seung-Hyun Cho , Seung-Jae Lee , Sa-Ouk Kang; J. Microbiol. 2011;49(1):71-77. Published online March 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0507-5

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Abstract: Vegetative mycelia of Pleurotus ostreatus were differentiated into primordia and subsequently into fruit bodies in synthetic sucrose-asparagine medium when exposed to light at low temperature. During photomorphogenesis, L-ascorbic acid-like substances called reductones were produced. L-Ascorbic acid, D-erythroascorbic acid, 5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid and 5-methyl-5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid were accumulated initially in the illuminated mycelia before the initiation of fruiting. The content of glycosides of erythroascorbic acid and their methylated compounds increased again in the primordia and the fruit bodies. Exogenous L-ascorbic acid induced the formation of primordia from the mycelia in the dark in a dose-dependent manner. Thus, this suggests that these reductones might play a role in mediating the light stimulus in photomorphogenesis.

Intracellular Substrates of a Heme-Containing Ascorbate Oxidase in Pleurotus ostreatus: Seung-Rock Lee , Woo-Jeong Joo , Yong-Un Baek , Youn-Kyong Lee , Seong-Woon Yu , Yeon-Ran Kim , Kee-Oh Chay , Seung-Hyun Cho , Sa-Ouk Kang; J. Microbiol. 2009;47(2):178-186. Published online May 2, 2009; DOI: https://doi.org/10.1007/s12275-008-0307-8

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Abstract: A novel heme-containing ascorbate oxidase isolated from oyster mushroom, Pleurotus ostreatus, catalyzes oxidation of ascorbic acid (Kim et al., 1996). In this report, we describe the identification of intracellular substrates of the enzyme in the mushroom. Six compounds, which can serve as substrate of the heme-containing ascorbate oxidase, were identified as L-ascorbic acid, D-erythroascorbic acid, 5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, and 5-methyl-5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid. All of the compounds were oxidized at a significant rate by the heme-containing ascorbate oxidase. Oxidation of the compounds produced equimolar amounts of hydrogen peroxide per mole of substrate.

A Bacterium Belonging to the Burkholderia cepacia Complex Associated with Pleurotus ostreatus: Ricardo Yara , Walter Maccheroni Junior , Jorge Horii , Joao Lucio Azevedo; J. Microbiol. 2006;44(3):263-268.; DOI: https://doi.org/2387 [pii]

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Abstract: Pleurotus ostreatus is a widely cultivated white-rot fungus. Owing to its considerable enzymatic versatility P. ostreatus has become the focus of increasing attention for its possible utility in biobleaching and bioremediation applications. Interactions between microorganisms can be an important factor in those processes. In this study, we describe the presence of a bacterial species associated with P. ostreatus strain G2. This bacterial species grew slowly (approximately 30 days) in theliquid and semi-solid media tested. When P. ostreatus was inoculated in solid media containing Tween 80 or Tween 20, bacterial microcolonies were detected proximal to the fungal colonies, and the relevant bacterium was identified via the analysis of a partial 16S rDNA sequence; it was determined to belong to the Burkholderia cepacia complex, but was not closely related to other fungus-isolated Burkholderiaceae. New specific primers were designed, and confirmed the presence of in vitro P. ostreatus cultures. This is the first time that a bacterial species belonging to the B. cepacia complex has been found associated with P. ostreatus.

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