Journal of Microbiology

Volume 53(12); December 2015

Review

MINIREVIEW] Histone deacetylase-mediated morphological transition in Candida albicans: Jueun Kim , Ji-Eun Lee , Jung-Shin Lee; J. Microbiol. 2015;53(12):805-811. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5488-3

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Abstract: Candida albicans is the most common opportunistic fungal pathogen, which switches its morphology from single-cell yeast to filament through the various signaling pathways responding to diverse environmental cues. Various transcriptional factors such as Nrg1, Efg1, Brg1, Ssn6, and Tup1 are the key components of these signaling pathways. Since C. albicans can regulate its transcriptional gene expressions using common eukaryotic regulatory systems, its morphological transition by these signaling pathways could be linked to the epigenetic regulation by chromatin structure modifiers. Histone proteins, which are critical components of eukaryotic chromatin structure, can regulate the eukaryotic chromatin structure through their own modifications such as acetylation, methylation, phosphorylation and ubiquitylation. Recent studies revealed that various histone modifications, especially histone acetylation and deacetylation, participate in morphological transition of C. albicans collaborating with well-known transcription factors in the signaling pathways. Here, we review recent studies about chromatin-mediated morphological transition of C. albicans focusing on the interaction between transcription factors in the signaling pathways and histone deacetylases.

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

Pyrosequencing reveals bacterial diversity in Korean traditional wheat-based nuruk: Jyotiranjan Bal , Suk-Hyun Yun , Myoung-Suk Choi , Soo-Hwan Yeo , Jung-Mi Kim , Dae-Hyuk Kim; J. Microbiol. 2015;53(12):812-819. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5516-3

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16 Citations

Abstract: The emerging global importance of Korea’s alcoholic beverages emphasizes the need for quality enhancement of nuruk, a traditional Korean cereal starter that is used extensively in traditional brewing. Apart from fungi and yeasts, bacteria known to be ubiquitously present are also a part of the nuruk ecosystem and are known to influence fermentation activity by influencing fermentation favorable factors. In the current study, bacterial diversity and temporal variations in the traditional wheat-based nuruk, fermented at two representative temperature conditions for 30 days, along with two commercial wheat-based nuruk samples for comparison analysis were evaluated using libraries of PCR amplicons and 454 pyrosequencing targeting of the hypervariable regions V1 to V3 of the 16S rRNA gene. A total of 90,836 16S reads were analyzed and assigned to a total of 314, 321, and 141 Operational Taxonomic Units (OTUs) for nuruk A, B, and C, respectively. Diversity parameters clearly indicated nuruk B to be more diverse in terms of bacterial composition than nuruk A. Taxonomic assignments indicated that nuruk A was dominated by phylum Cyanobacteria, whereas nuruk B was dominated by phylum Actinobacteria. For both nuruk A and B, members of the phylum Firmicutes mostly converged into the family Bacillaceae; these microorganisms might be present in negligible numbers at the beginning but became significant as the fermentation progressed. The commercial samples were predominated by phylum Firmicutes, which is composed of Lactobacillaceae and Leoconostocaceae. The findings of this study provide new insights into understanding the changes in bacterial community structure during traditional nuruk starter production.

Characterization of cell death in Escherichia coli mediated by XseA, a large subunit of exonuclease VII: Hyeim Jung , Junwei Liang , Yuna Jung , Dongbin Lim; J. Microbiol. 2015;53(12):820-828. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5304-0

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Abstract: Exonuclease VII (ExoVII) of Escherichia coli is a single strandspecific DNA nuclease composed of two different subunits: the large subunit, XseA, and the small subunit, XseB. In this study, we found that multicopy single-stranded DNAs (msDNAs), Ec83 and Ec78, are the in vivo substrates of ExoVII; the enzyme cuts the phosphodiester bond between the fourth and fifth nucleotides from the 5′ end. We used this msDNA cleavage to assess ExoVII activity in vivo. Both subunits were required for enzyme activity. Expression of XseA without XseB caused cell death, even though no ExoVII activity was detected. The lethality caused by XseA was rescued by surplus XseB. In XseA-induced death, cells were elongated and multinucleated, and their chromosomes were fragmented and condensed; these are the morphological hallmarks of apoptotic cell death in bacteria. A putative caspase recognition sequence (FVAD) was found in XseA, and its hypothetical caspase product with 257 amino acids was as active as the intact protein in inducing cell death. We propose that under ordinary conditions, XseA protects chromosome as a component of the ExoVII enzyme, but in some conditions, the protein causes cell death; the destruction of cell is probably carried out by the amino terminal fragment derived from the cleavage of XseA by caspase-like enzyme.

Inhibition of quorum sensing, biofilm, and spoilage potential in Shewanella baltica by green tea polyphenols: Junli Zhu , Xuzheng Huang , Fang Zhang , Lifang Feng , Jianrong Li; J. Microbiol. 2015;53(12):829-836. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5123-3

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73 Citations

Abstract: We investigated the quorum sensing (QS) system of Shewanella baltica and the anti-QS related activities of green tea polyphenols (TP) against spoilage bacteria in refrigerated large yellow croaker. Autoinducer-2 (AI-2) and the diketopiperazines (DKPs) cyclo-(L-Pro-L-Leu) and cyclo-(L-Pro-L-Phe) were detected in the culture extract of S. baltica XH2, however, no N-acylhomoserine lactones (AHLs) activity was observed. Green TP at sub-inhibitory concentrations interfered with AI-2 and DKPs activities of S. baltica without inhibiting cell growth and promoted degradation of AI-2. The green TP treatment inhibited biofilm development, exopolysaccharide production and swimming motility of S. baltica in a concentration- dependent manner. In addition, green TP decreased extracellular protease activities and trimethylamine production in S. baltica. A transcriptional analysis showed that green TP repressed the luxS and torA genes in S. baltica, which agreed with the observed reductions in QS activity and the spoilage phenotype. Epigallocatechin gallate (EGCG)-enriched in green TP significantly inhibited AI-2 activity of S.baltica. These findings strongly suggest that green TP could be developed as a new QS inhibitor for seafood preservation to enhance shelf life.

In silico analysis and experimental validation of lipoprotein and novel Tat signal peptides processing in Anabaena sp. PCC7120: Sonika Kumari , Akhilesh Kumar Chaurasia; J. Microbiol. 2015;53(12):837-846. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5281-3

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Abstract: Signal peptide (SP) plays a pivotal role in protein translocation. Lipoprotein- and twin arginine translocase (Tat) dependent signal peptides were studied in All3087, a homolog of competence protein of Synechocystis PCC6803 and in two putative alkaline phosphatases (ALPs, Alr2234 and Alr4976), respectively. In silico analysis of All3087 is shown to possess the characteristics feature of competence proteins such as helix-hairpin-helix, N and C-terminal HKD endonuclease domain, calcium binding domain and N-terminal lipoprotein signal peptide. The SP recognition-cleavage site in All3087 was predicted (AIA-AC) using SignalP while further in-depth analysis using Pred-Lipo and WebLogo analysis for consensus sequence showed it as IAA-C. Activities of putative ALPs were confirmed by heterologous overexpression, activity assessment and zymogram analysis. ALP activity in Anabaena remains cell bound in log-phase, but during late log/stationary phase, an enhanced ALP activity was detected in extracellular milieu. The enhancement of ALP activity during stationary phase was not only due to inorganic phosphate limitation but also contributed by the presence of novel bipartite Tat-SP. The Tat signal transported the folded active ALPs to the membrane, followed by anchoring into the membrane and successive cleavage enabling transportation of the ALPs to the extracellular milieu, because of bipartite architecture and processing of transit Tat-SP.

In vivo antimalarial activity of the endophytic actinobacteria, Streptomyces SUK 10: Mohd Shukri Baba , Noraziah Mohamad Zin , Zainal Abidin Abu Hassan , Jalifah Latip , Florence Pethick , Iain S. Hunter , RuAngelie Edrada-Ebel , Paul R. Herron; J. Microbiol. 2015;53(12):847-855. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5076-6

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23 Citations

Abstract: Endophytic bacteria, such as Streptomyces, have the potential to act as a source for novel bioactive molecules with medicinal properties. The present study was aimed at assessing the antimalarial activity of crude extract isolated from various strains of actinobacteria living endophytically in some Malaysian medicinal plants. Using the four day suppression test method on male ICR strain mice, compounds produced from three strains of Streptomyces (SUK8, SUK10, and SUK27) were tested in vivo against Plasmodium berghei PZZ1/100 in an antimalarial screen using crude extracts at four different concentrations. One of these extracts, isolated from Streptomyces SUK10 obtained from the bark of Shorea ovalis tree, showed inhibition of the test organism and was further tested against P. berghei-infected mice for antimalarial activity at different concentrations. There was a positive relationship between the survival of the infected mouse group treated with 50 μg/kg body weight (bw) of ethyl acetate-SUK10 crude extract and the ability to inhibit the parasites growth. The parasite inhibition percentage for this group showed that 50% of the mice survived for more than 90 days after infection with the parasite. The nucleotide sequence and phylogenetic tree suggested that Streptomyces SUK10 may constitute a new species within the Streptomyces genus. As part of the drug discovery process, these promising finding may contribute to the medicinal and pharmaceutical field for malarial treatment.

Lactobacillus rhamnosus CCFM1107 treatment ameliorates alcohol-induced liver injury in a mouse model of chronic alcohol feeding: Fengwei Tian , Feifei Chi , Gang Wang , Xiaoming Liu , Qiuxiang Zhang , Yongquan Chen , Hao Zhang , Wei Chen; J. Microbiol. 2015;53(12):856-863. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5239-5

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54 Citations

Abstract: Lactobacillus rhamnosus CCFM1107 was screened for high antioxidative activity from 55 lactobacilli. The present study attempted to explore the protective properties of L. rhamnosus CCFM1107 in alcoholic liver injury. A mouse model was induced by orally feeding alcohol when simultaneously treated with L. rhamnosus CCFM1107, the drug Hu-Gan- Pian (HGP), L. rhamnosus GG (LGG), and L. plantarum CCFM1112 for 3 months. Biochemical analysis was performed for both serum and liver homogenate. Detailed intestinal flora and histological analyses were also carried out. Our results indicated that the administration of L. rhamnosus CCFM1107 significantly inhibited the increase in the levels of serum aminotransferase and endotoxin, as well as the levels of triglyceride (TG) and cholesterol (CHO) in the serum and in the liver. Glutathione (GSH), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were elevated while the levels of malondialdehyde (MDA) were decreased. The enteric dysbiosis caused by alcohol was restored by increasing the numbers of both lactobacilli and bifidobacteria and decreasing the numbers of both enterococci and enterobacter. Histological analysis confirmed the protective effect of L. rhamnosus CCFM1107. Compared with the other lactobacilli and to the drug Hu-Gan-Pian, there is a high chance that L. rhamnosus CCFM1107 provides protective effects on alcoholic liver injury by reducing oxidative stress and restoring the intestinal flora.

Innate signaling mechanisms controlling Mycobacterium chelonae-mediated CCL2 and CCL5 expression in macrophages: Yi Sak Kim , Ji Hye Kim , Minjeong Woo , Tae-sung Kim Kim , Kyung Mok Sohn , Young-Ha Lee , Eun-Kyeong Jo , Jae-Min Yuk; J. Microbiol. 2015;53(12):864-874. Published online December 2, 2015; DOI: https://doi.org/10.1007/s12275-015-5348-1

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Abstract: Mycobacterium chelonae (Mch) is an atypical rapidly growing mycobacterium (RGM) that belongs to the M. chelonae complex, which can cause a variety of human infections. During this type of mycobacterial infection, macrophagederived chemokines play an important role in the mediation of intracellular communication and immune surveillance by which they orchestrate cellular immunity. However, the intracellular signaling pathways involved in the macrophage- induced chemokine production during Mch infections remain unknown. Thus, the present study aimed to determine the molecular mechanisms by which Mch activates the gene expressions of chemokine (C-C motif) ligand 2 (CCL2) and CCL5 in murine bone marrow-derived macrophages (BMDMs) and in vivo mouse model. Toll-like receptor 2 (TLR2)-deficient mice showed increased bacterial burden in spleen and lung and decreased protein expression of CCL2 and CCL5 in serum. Additionally, Mch infection triggered the mRNA and protein expression of CCL2 and CCL5 in BMDMs via TLR2 and myeloid differentiation primary response gene 88 (MyD88) signaling and that it rapidly activated nuclear factor (NF)-κB signaling, which is required for the Mch-induced expressions of CCL2 and CCL5 in BMDMs. Moreover, while the innate receptor Dectin-1 was only partly involved in the Mch-induced expression of the CCL2 and CCL5 chemokines in BMDMs, the generation of intracellular reactive oxygen species (ROS) was an important contributor to these processes. Taken together, the present data indicate that the TLR2, MyD88, and NF-κB pathways, Dectin-1 signaling, and intracellular ROS generation contribute to the Mch-mediated expression of chemokine genes in BMDMs.

Published Erratum

Erratum] The Mycobacterium tuberculosis relBE toxin:antitoxin genes are stress-responsive modules that regulate growth through translation inhibition: Shaleen B. Korch , Vandana Malhotra , Heidi Contreras , Josephine E. Clark-Curtiss; J. Microbiol. 2015;53(12):875-875.; DOI: https://doi.org/10.1007/s12275-015-0741-3

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Abstract: In the article by Korch et al. published in Journal of Microbiology 2015; 53, 783-795. The authors’ affiliation of this paper should be changed as below

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