Journal of Microbiology

Volume 57(9); September 2019

Review

MINIREVIEW] Fungi in salterns: Dawoon Chung† , Haryun Kim† , Hyun Seok Choi; J. Microbiol. 2019;57(9):717-724. Published online August 27, 2019; DOI: https://doi.org/10.1007/s12275-019-9195-3

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53 Citations

Abstract: Salterns are hypersaline extreme environments with unique physicochemical properties such as a salinity gradient. Although the investigation of microbiota in salterns has focused on archaea and bacteria, diverse fungi also thrive in the brine and soil of salterns. Fungi isolated from salterns are represented by black yeasts (Hortaea werneckii, Phaeotheca triangularis, Aureobasidium pullulans, and Trimmatostroma salinum), Cladosporium, Aspergillus, and Penicillium species. Most studies on saltern-derived fungi gave attention to black yeasts and their physiological characteristics, including growth under various culture conditions. Since then, biochemical and molecular tools have been employed to explore adaptation of these fungi to salt stress. Genome databases of several fungi in salterns are now publicly available and being used to elucidate salt tolerance mechanisms and discover the target genes for agricultural and industrial applications. Notably, the number of enzymes and novel metabolites known to be produced by diverse saltern-derived fungi has increased significantly. Therefore, fungi in salterns are not only interesting and important subjects to study fungal biodiversity and adaptive mechanisms in extreme environments, but also valuable bioresources with potential for biotechnological applications.

Journal Articles

Aeromicrobium endophyticum sp. nov., an endophytic actinobacterium isolated from reed (Phragmites australis): Fei-Na Li , Shui-Lin Liao , Shao-Wei Liu , Tao Jin , Cheng-Hang Sun; J. Microbiol. 2019;57(9):725-731. Published online May 23, 2019; DOI: https://doi.org/10.1007/s12275-019-8705-7

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26 Citations

Abstract: A Gram-staining-positive, motile and short-rod-shaped actinobacterium designated 9W16Y-2T was isolated from surface- sterilized leaves of reed (Phragmites australis) collected from Taklamakan Desert in Xinjiang Uygur Autonomous Region, China. Colonies were pale greenish yellow, circular, smooth, and convex. The 16S rRNA gene sequence of strain 9W16Y-2T exhibited highest sequence similarities with Aeromicrobium camelliae CGMCC 1.12942T (99.0%) and Aeromicrobium erythreum NRRL B-3381T (97.2%). Phylogenetic analyses based on 16S rRNA gene sequences and single-copy phylogenetic marker genes (pMGs) showed that strain 9W16Y- 2T belonged to the genus Aeromicrobium and formed a monophyletic clade with Aeromicrobium camelliae CGMCC 1.12942T. Furthermore, average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) clearly separated strain 9W16Y-2T from the other species of the genus Aeromicrobium with values below the thresholds for species delineation. The G+C content of the genomic DNA is 68.9 mol%. The diagnostic diamino acid of the cell-wall peptidoglycan was LLdiaminopimelic acid. The predominant menaquinone was MK-9(H4). The major fatty acids (> 10% of the total fatty acids) were C18:0 10-methyl (TBSA) (28.2%), C16:0 (21.0%), C16:0 2-OH (20.8%) and C18:1 ω9c (12.8%). The polar lipid profile comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, an unidentified aminophospholipid and an unidentified lipid. Based on the phylogenic, phenotypic and chemotaxonomic features, strain 9W16Y-2T represents a novel species of the genus Aeromicrobium, for which the name Aeromicrobium endophyticum sp. nov. is proposed. The type strain is 9W16Y-2T (= CGMCC 1.13876T = JCM 33141T).

Arthrobacter dokdonellae sp. nov., isolated from a plant of the genus Campanula: Hyeon-Woo Koh , Myung-Suk Kang , Ki-Eun Lee , Eun-Young Lee , Hongik Kim , Soo-Je Park; J. Microbiol. 2019;57(9):732-737. Published online May 11, 2019; DOI: https://doi.org/10.1007/s12275-019-8540-x

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Abstract: A Gram-stain-positive, oxidase- and catalase-positive, motile, aerobic, and rod-shaped bacterial strain, designated as DCT-5T, was isolated from a native plant belonging to the genus Campanula at Dokdo island, Republic of Korea. Growth of the strain DCT-5T was observed at 15–37°C (optimum 30°C) on R2A broth, pH 6.0–8.0 (optimum 7.0), and 0–5% (w/v) NaCl concentration (optimum 0%). The 16S rRNA gene sequence analysis revealed that strain DCT-5T was most closely related to Arthrobacter silviterrae KIS14-16T, Arthrobacter livingstonensis LI2T, Arthrobacter stackebrandtii CCM 2783T, Arthrobacter cryoconiti Cr6-08T, Arthrobacter ramosus CCM 1646T, and Arthrobacter psychrochitiniphilus GP3T with pairwise sequence similarities of 98.76%, 97.47%, 97.25%, 97.11%, 97.11%, and 97.00%, respectively. The DNA G+C content of strain DCT-5T was 64.7 mol%, and its DNA–DNA relatedness values with A. silviterrae KIS14-16T, A. livingstonensis LI2T, A. stackebrandtii CCM 2783T, A. psychrochitiniphilus GP3T, A. ramosus CCM 1646T, and A. cryoconiti Cr6-08T were 32.57 ± 2.02%, 28.75 ± 0.88%, 31.93 ± 1.15%, 34.73 ± 1.86%, 29.12 ± 1.56%, and 27.23 ± 0.88%, respectively. The major quinone was MK-9(H2) and major fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C15:0, and iso-C16:0. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylinositol (PI), unidentified glycolipid (GL), two unidentified aminophospholipids (APLs), and three unidentified lipids (Ls). The peptidoglycan type was A3α. On the basis of phenotypic, phylogenetic, genotypic, and chemotaxonomic characteristics, strain DCT-5T represents a novel species of the genus Arthrobacter, for which the name Arthrobacter dokdonellae sp. nov. is proposed. The type strain is DCT-5T (= KCTC 49189T = LMG 31284T).

Reduction of selenite to elemental Se(0) with simultaneous degradation of phenol by co-cultures of Phanerochaete chrysosporium and Delftia lacustris: Samayita Chakraborty , Eldon R. Rene , Piet N. L. Lens; J. Microbiol. 2019;57(9):738-747. Published online August 3, 2019; DOI: https://doi.org/10.1007/s12275-019-9042-6

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Abstract: The simultaneous removal of phenol and selenite from synthetic wastewater was investigated by adopting two different co-culturing techniques using the fungus Phanerochaete chrysosporium and the bacterium Delftia lacustris. Separately grown biomass of the fungus and the bacterium (suspended co-culture) was incubated with different concentrations of phenol (0–1,200 mg/L) and selenite (10 mg/L). The selenite ions were biologically reduced to extracellular Se(0) nanoparticles (3.58 nm diameter) with the simultaneous degradation of up to 800 mg/L of phenol. Upon growing the fungus and the bacterium together using an attached growth co-culture, the bacterium grew as a biofilm onto the fungus. The extracellularly produced Se(0) in the attached growth co-culture had a minimum diameter of 58.5 nm. This co-culture was able to degrade completely 50 mg/L phenol, but was completely inhibited at a phenol concentration of 200 mg/L.

Characteristics of the gut microbiota colonization, inflammatory profile, and plasma metabolome in intrauterine growth restricted piglets during the first 12 hours after birth: Shimeng Huang , Na Li , Cong Liu , Tiantian Li , Wei Wang , Lili Jiang , Zhen Li , Dandan Han , Shiyu Tao , Junjun Wang; J. Microbiol. 2019;57(9):748-758. Published online June 11, 2019; DOI: https://doi.org/10.1007/s12275-019-8690-x

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49 Citations

Abstract: Intrauterine growth restriction (IUGR) predisposes newborns to inflammatory and metabolic disturbance. Disequilibrium of gut microbiota in early life has been implicated in the incidence of inflammation and metabolic diseases in adulthood. This study aimed to investigate the difference in gut microbiota colonization, cytokines and plasma metabolome between IUGR and normal birth weight (NBW) piglets in early life. At birth, reduced (P < 0.05) body, jejunum, and ileum weights, as well as decreased (P < 0.05) small intestinal villi and increased (P < 0.05) ileal crypt depth were observed in IUGR piglets compared with their NBW counterparts. Imbalanced inflammatory and plasma metabolome profile was observed in IUGR piglets. Furthermore, altered metabolites were mainly involved in fatty acid metabolism and inflammatory response. At 12 h after birth and after suckling colostrum, reduced (P < 0.05) postnatal growth and the small intestinal maturation retardation (P < 0.05) continued in IUGR piglets in comparison with those in NBW littermates. Besides, the gut microbiota structure was significantly altered by IUGR. Importantly, the disruption of the inflammatory profile and metabolic status mainly involved the pro-inflammatory cytokines (IL-1β and IFN-γ) and amino acid metabolism. Moreover, spearman correlation analysis showed that the increased abundance of Escherichia-Shigella and decreased abundance of Clostridium_sensu_stricto_1 in IUGR piglets was closely associated with the alterations of slaughter weight, intestinal morphology, inflammatory cytokines, and plasma metabolites. Collectively, IUGR significantly impairs small intestine structure, modifies gut microbiota colonization, and disturbs inflammatory and metabolic profiles during the first 12 h after birth. The unbalanced gut microbiota mediated by IUGR contributes to the development of inflammation and metabolic diseases.

Diluted conventional media improve the microbial cultivability from aquarium seawater: Jing Sun , Jiazhen Guo , Qian Yang , Jie Huang; J. Microbiol. 2019;57(9):759-768. Published online August 3, 2019; DOI: https://doi.org/10.1007/s12275-019-9175-7

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9 Citations

Abstract: The cultivation of microbial species remains a primary challenge in microbiology and obtaining pure cultures is essential for the study of microbial physiology and function. When isolating microorganisms from aquaculture environments, Vibrio are the most dominate isolates on the media that are commonly used. In order to expand our ability to study microbial species, an easy-operation and low-cost medium that can reduce the interference of Vibrio strains and increase the cultivability of other bacteria is urgently needed. We compared viable cell counts on conventional media (CM; including Marine Agar 2216 and LB media) and diluted media (DM; including 1/10-Marine Agar 2216, 1/10-LB). We also assessed the diversity of cultivable microorganisms under high and low nutrient conditions by a plate-wash strategy coupled with high-throughput sequencing of the V4 hypervariable region of the 16S rRNA gene. The results show that microbial communities from DM, especially 1/10-Marine Agar 2216, are more diverse than those obtained from CM. Vibrio isolates were reduced on DM. PICRUSt analysis revealed that nutrient composition is a significant contributor to the diversity and function of the cultivable microbial communities. Bacteria grown on CM possess more pathogenic characteristics, whereas DM favors the growth of bacteria that have multiple metabolic functions. Collectively, our data provide strong evidence that dilution of CM influences the cultivability of bacteria from aquaculture seawater. It also supports that DM can expand the range of microbial species that can be cultivated. This study also provides insights for media design in microbial cultivation from aquaculture systems.

Transcriptomic and proteomic profiling revealed global changes in Streptococcus thermophilus during pH-controlled batch fermentations: Yali Qiao , Cong Leng , Gefei Liu , Yanjiao Zhang , Xuepeng Lv , Hongyu Chen , Jiahui Sun , Zhen Feng; J. Microbiol. 2019;57(9):769-780. Published online June 14, 2019; DOI: https://doi.org/10.1007/s12275-019-8604-y

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Abstract: Understanding global changes of physiological processes at the molecular level during the growth of Streptococcus thermophilus is essential for the rational design of cultivation media and the optimization of bioprocesses. Transcriptomics and proteomics were combined to investigate the global changes at the transcript and protein level during the growth of S. thermophilus. The expression of 1396 genes (FDR ≤ 0.001) and 876 proteins (P < 0.05) changed significantly over time. The most remarkable growth phase dependent changes occurred in the late-lag phase and were related to heterofermentation, glycolysis, peptidoglycan biosynthesis, conversion between amino acids and stress response. The present
results
could provide theoretical guidance for high-cell-density culture, help design cultivation media, and help attain a high biomass of S. thermophilus.

Transcriptome analysis to understand the effects of the toxoflavin and tropolone produced by phytopathogenic Burkholderia on Escherichia coli: Jungwook Park , Hyun-Hee Lee , Hyejung Jung , Young-Su Seo; J. Microbiol. 2019;57(9):781-794. Published online August 27, 2019; DOI: https://doi.org/10.1007/s12275-019-9330-1

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Abstract: The phytopathogenic Burkholderia species B. glumae and B. plantarii are the causal agents of bacterial wilt, grain rot, and seedling blight, which threaten the rice industry globally. Toxoflavin and tropolone are produced by these phytopathogens and are considered the most hostile biohazards with a broad spectrum of target organisms. However, despite their nonspecific toxicity, the effects of toxoflavin and tropolone on bacteria remain unknown. RNA-seq based transcriptome analysis was employed to determine the genome-wide expression patterns under phytotoxin treatment. Expression of 2327 and 830 genes was differentially changed by toxoflavin and tropolone, respectively. Enriched biological pathways reflected the down-regulation of oxidative phosphorylation and ribosome function, beginning with the inhibition of membrane biosynthesis and nitrogen metabolism under oxidative stress or iron starvation. Conversely, several systems such as bacterial chemotaxis, flagellar assembly, biofilm formation, and sulfur/taurine transporters were highly expressed as countermeasures against the phytotoxins. In addition, our findings revealed that three hub genes commonly induced by both phytotoxins function as the siderophore enterobactin, an ironchelator. Our study provides new insights into the effects of phytotoxins on bacteria for better understanding of the interactions between phytopathogens and other microorganisms. These data will also be applied as a valuable source in subsequent applications against phytotoxins, the major virulence factor.

Mutants defective in the production of encapsulin show a tan-phaselocked phenotype in Myxococcus xanthus: Dohee Kim , Juo Choi , Sunjin Lee , Hyesook Hyun , Kyoung Lee , Kyungyun Cho; J. Microbiol. 2019;57(9):795-802. Published online June 11, 2019; DOI: https://doi.org/10.1007/s12275-019-8683-9

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Abstract: Myxococcus xanthus, a myxobacterium, displays phase variation between yellow phase and tan phase. We found that deletion of the encA gene encoding encapsulin and the encF gene encoding a metalloprotease causes formation of tan colonies that never transform into yellow colonies. The encA and encF mutants were defective in the production of DKxanthene and myxovirescin. They did not produce extracellular polysaccharides; hence, the cells did not aggregate in liquid and showed reduced swarming on agar plates. The mutants had defective sporulation, but were rescued extracellularly by wild type cells. All these traits indicate that the encA and encF mutants are likely to be tan-phase-locked, and encapsulin has a close relationship with phase variation in M. xanthus. The encA and encF genes are localized in the same gene cluster, encBAEFG (MXAN_3557~MXAN_3553). Unlike the encA and encF genes, deletion of other genes in the cluster did not show tan-phase-locked phenotype.

Middle East respiratory syndrome coronavirus-encoded ORF8b strongly antagonizes IFN-β promoter activation: its implication for vaccine design: Jeong Yoon Lee , Sojung Bae , Jinjong Myoung; J. Microbiol. 2019;57(9):803-811. Published online August 27, 2019; DOI: https://doi.org/10.1007/s12275-019-9272-7

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38 Citations

Abstract: Middle East respiratory syndrome coronavirus (MERS-CoV) is a causative agent of severe-to-fatal pneumonia especially in patients with pre-existing conditions, such as smoking and chronic obstructive pulmonary disease (COPD). MERS-CoV transmission continues to be reported in the Saudi Arabian Peninsula since its discovery in 2012. However, it has rarely been epidemic outside the area except one large outbreak in South Korea in May 2015. The genome of the epidemic MERS-CoV isolated from a Korean patient revealed its homology to previously reported strains. MERS-CoV encodes 5 accessory proteins and generally, they do not participate in the genome transcription and replication but rather are involved in viral evasion of the host innate immune responses. Here we report that ORF8b, an accessory protein of MERSCoV, strongly inhibits both MDA5- and RIG-I-mediated activation of interferon beta promoter activity while downstream signaling molecules were left largely unaffected. Of note, MDA5 protein levels were significantly down-regulated by ORF8b and co-expression of ORF4a and ORF4b. These novel findings will facilitate elucidation of mechanisms of virus-encoded evasion strategies, thus helping design rationale antiviral countermeasures against deadly MERS-CoV infection.

A newly characterized exopolysaccharide from Sanghuangporus sanghuang: Xiao-kui Ma , Xu She , Eric Charles Peterson , Yu Zhen Wang , Peng Zheng , Hongyan Ma , Kexin Zhang , Jian Liang; J. Microbiol. 2019;57(9):812-820. Published online June 14, 2019; DOI: https://doi.org/10.1007/s12275-019-9036-4

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26 Citations

Abstract: Sanghuangporus sanghuang is a well-known pharmacodynamic and economically important edible fungus associated with mulberry (Morus spp.). A distinctly new exopolysaccharide (EPS), designated SHP-2 was obtained from S. sanghuang P0988 broth, and its structure and anti-aging prosperity were characterized. SHP-2 was found to be composed of a backbone of 􎵔4)-β-Manp-(1􎵔4)-α-Araf-(1􎵔3,4)-α-Glcp(1􎵔􀁇 3,4)-α-Glcp-(1􎵔3,4)-α-Glcp-(1􎵔3,4)-α-Glcp-(1􎵔3,4)-α- Glcp-(1􎵔6)-α-Galp-(1􎵔4)-β-Manp-(1􎵔􀁇and five branches, including four α-D-Glcp-(1􎵔􀁇and one α-D-Manp-(1􎵔􀁇 SHP-2 was shown to increase antioxidant enzyme activities including catalase (CAT) and superoxide dismutase (SOD) activities, as well as trolox equivalent antioxidant (TEAC) capacity in serum of mice pre-treated with D-Gal, while reducing lipofuscin levels. SHP-2 exerted a favorable influence on immune organ coefficients and ameliorated the histopathological hepatic lesions and apoptosis in hepatocytes of Dgalactose- aged mice almost in a dose-dependent manner. Using the same analytical methods, on comparison with previously studied EPS compounds (i.e. SHP-1), SHP-2 was found to have more complex structure, larger molecule weight, and different anti-aging properties. The results presented here suggest that not only does EPS bioactivity vary with respect to molecular structures and molecule weight, but that multiple structures with different activity can be expressed by a single fungal strain. These results may help understanding the antiaging prosperity of these polysaccharides for use in health foods or dietary supplements.

IgG and IgM responses to human papillomavirus L1 virus-like particle as a function of dosing schedule and vaccine formulation: Min-Hye Park , Ji Won You , Hyoung Jin Kim , Hong-Jin Kim; J. Microbiol. 2019;57(9):821-827. Published online August 27, 2019; DOI: https://doi.org/10.1007/s12275-019-9308-z

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Abstract: Most commercialized virus-like particle (VLP) vaccines use aluminum salt as adjuvant, even though VLPs provoke adequate antibody responses without adjuvant. We do not have detailed knowledge of how adjuvant affects the profile of anti- VLP antibodies. Meanwhile, there is evidence that differences between vaccination protocols influence the glycosylation of antibodies, which may alter their effector functions. In the present study a murine model was used to investigate the effects of dosing schedule and adjuvant on the antibody profiles and glycosylation levels of antigen-specific antibody responses to human papillomavirus type 16 L1 (HPV16 L1) VLPs. Mice received subcutaneously 2,000 ng of antigen divided into 4 or 7 doses. The HPV16 L1 VLPs elicited > 4 log10 anti-HPV16 L1 IgG titers without adjuvant, and aluminum hydroxide as adjuvant increased IgG titers 1.3- to 4-fold and reduced the anti-HPV16 L1 IgG2a / anti-HPV16 L1 IgG1 ratio value (use of aluminum hydroxide reduced the ratio of the IgG2a). Immunization with HPV16 L1 VLPs in combination with Freund’s adjuvant enhanced IgG titers 5- to 12- fold. Seven-dose immunization markedly increased anti- HPV16 L1 IgM titers compared to four-dose immunization, as well as increasing the proportion of glycosylated antibodies. Our results suggest that antibody glycosylation can be controlled immunologically, and IgG and IgM profiles and glycosylation profiles of the vaccine-induced antibodies can be used as indicators reflecting the vaccine characteristics. These
results
indicate that the HPV16 L1 VLP dosing schedule can affect the quality of antigen-specific antibody responses. We suggest that dosing schedules should be noted in vaccination protocols for VLP-based vaccines.

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