Displaying publications 81 - 100 of 370 in total

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  1. Fulltext Exosomes drive ferroptosis by stimulating iron accumulation to inhibit bacterial infection in crustaceans
    Sun Q, Yang J, Zhang M, Zhang Y, Ma H, Tran NT, et al.
    J Biol Chem, 2023 Dec;299(12):105463.
    PMID: 37977221 DOI: 10.1016/j.jbc.2023.105463
    Ferroptosis, characterized by iron-dependent cell death, has recently emerged as a critical defense mechanism against microbial infections. The present study aims to investigate the involvement of exosomes in the induction of ferroptosis and the inhibition of bacterial infection in crustaceans. Our findings provide compelling evidence for the pivotal role of exosomes in the immune response of crustaceans, wherein they facilitate intracellular iron accumulation and activate the ferroptotic pathways. Using RNA-seq and bioinformatic analysis, we demonstrate that cytochrome P450 (CYP) can effectively trigger ferroptosis. Moreover, by conducting an analysis of exosome cargo proteins, we have identified the participation of six-transmembrane epithelial antigen of prostate 4 in the regulation of hemocyte ferroptotic sensitivity. Subsequent functional investigations unveil that six-transmembrane epithelial antigen of prostate 4 enhances cellular Fe2+ levels, thereby triggering Fenton reactions and accelerating CYP-mediated lipid peroxidation, ultimately culminating in ferroptotic cell death. Additionally, the Fe2+-dependent CYP catalyzes the conversion of arachidonic acid into 20-hydroxyeicosatetraenoic acid, which activates the peroxisome proliferator-activated receptor. Consequently, the downstream target of peroxisome proliferator-activated receptor, cluster of differentiation 36, promotes intracellular fatty acid accumulation, lipid peroxidation, and ferroptosis. These significant findings shed light on the immune defense mechanisms employed by crustaceans and provide potential strategies for combating bacterial infections in this species.
  2. Fulltext Microbial succession and the functional potential during the fermentation of Chinese soy sauce brine
    Sulaiman J, Gan HM, Yin WF, Chan KG
    Front Microbiol, 2014;5:556.
    PMID: 25400624 DOI: 10.3389/fmicb.2014.00556
    The quality of traditional Chinese soy sauce is determined by microbial communities and their inter-related metabolic roles in the fermentation tank. In this study, traditional Chinese soy sauce brine samples were obtained periodically to monitor the transitions of the microbial population and functional properties during the 6 months of fermentation process. Whole genome shotgun method revealed that the fermentation brine was dominated by the bacterial genus Weissella and later dominated by the fungal genus Candida. Metabolic reconstruction of the metagenome sequences demonstrated a characteristic profile of heterotrophic fermentation of proteins and carbohydrates. This was supported by the detection of ethanol with stable decrease of pH values. To the best of our knowledge, this is the first study that explores the temporal changes in microbial successions over a period of 6 months, through metagenome shotgun sequencing in traditional Chinese soy sauce fermentation and the biological processes therein.
  3. Diversity of microbiota associated with symptomatic and non-symptomatic bacterial wilt-diseased banana plants determined using 16S rRNA metagenome sequencing
    Suhaimi NSM, Goh SY, Ajam N, Othman RY, Chan KG, Thong KL
    World J Microbiol Biotechnol, 2017 Aug 21;33(9):168.
    PMID: 28828756 DOI: 10.1007/s11274-017-2336-0
    Banana is one of the most important fruits cultivated in Malaysia, and it provides many health benefits. However, bacterial wilt disease, which attacks bananas, inflicts major losses on the banana industry in Malaysia. To understand the complex interactions of the microbiota of bacterial wilt-diseased banana plants, we first determined the bacterial communities residing in the pseudostems of infected (symptomatic) and diseased-free (non-symptomatic) banana plants. We characterized the associated microorganisms using the targeted 16S rRNA metagenomics sequencing on the Illumina MiSeq platform. Taxonomic classifications revealed 17 and nine known bacterial phyla in the tissues of non-symptomatic and symptomatic plants, respectively. Cyanobacteria and Proteobacteria (accounted for more than 99% of the 16S rRNA gene fragments) were the two most abundant phyla in both plants. The five major genera found in both plant samples were Ralstonia, Sphingomonas, Methylobacterium, Flavobacterium, and Pseudomonas. Ralstonia was more abundant in symptomatic plant (59% out of the entire genera) as compared to those in the non-symptomatic plant (only 36%). Our data revealed that 102 bacterial genera were only assigned to the non-symptomatic plant. Overall, this study indicated that more diverse and abundant microbiota were associated with the non-symptomatic bacterial wilt-diseased banana plant as compared to the symptomatic plant. The higher diversity of endophytic microbiota in the non-symptomatic banana plant could be an indication of pathogen suppression which delayed or prevented the disease expression. This comparative study of the microbiota in the two plant conditions might provide caveats for potential biological control strategies.
  4. Fulltext High-quality Schistosoma haematobium genome achieved by single-molecule and long-range sequencing
    Stroehlein AJ, Korhonen PK, Chong TM, Lim YL, Chan KG, Webster B, et al.
    Gigascience, 2019 Sep 01;8(9).
    PMID: 31494670 DOI: 10.1093/gigascience/giz108
    BACKGROUND: Schistosoma haematobium causes urogenital schistosomiasis, a neglected tropical disease affecting >100 million people worldwide. Chronic infection with this parasitic trematode can lead to urogenital conditions including female genital schistosomiasis and bladder cancer. At the molecular level, little is known about this blood fluke and the pathogenesis of the disease that it causes. To support molecular studies of this carcinogenic worm, we reported a draft genome for S. haematobium in 2012. Although a useful resource, its utility has been somewhat limited by its fragmentation.

    FINDINGS: Here, we systematically enhanced the draft genome of S. haematobium using a single-molecule and long-range DNA-sequencing approach. We achieved a major improvement in the accuracy and contiguity of the genome assembly, making it superior or comparable to assemblies for other schistosome species. We transferred curated gene models to this assembly and, using enhanced gene annotation pipelines, inferred a gene set with as many or more complete gene models as those of other well-studied schistosomes. Using conserved, single-copy orthologs, we assessed the phylogenetic position of S. haematobium in relation to other parasitic flatworms for which draft genomes were available.

    CONCLUSIONS: We report a substantially enhanced genomic resource that represents a solid foundation for molecular research on S. haematobium and is poised to better underpin population and functional genomic investigations and to accelerate the search for new disease interventions.

  5. Core members and differential abundance of chrysomelid microbiota in the life stages of Podontiaaffinis (Galerucinae) and adult Silanafarinosa(Cassidinae, Coleoptera)
    Song SL, Yong HS, Chua KO, Eamsobhana P, Lim PE, Chan KG
    Biodivers Data J, 2022;10:e87459.
    PMID: 36761655 DOI: 10.3897/BDJ.10.e87459
    The chrysomelid beetlesPodontiaaffinis and Silanafarinosa are members of the subfamilies Galerucinae and Cassidinae, respectively. This study, based on 16S rRNA gene-targeted metagenomics sequencing, reports the core members and differential abundance of bacterial communities in the larvae and adult beetles of P.affinis and the adult S.farinosa. Cyanobacteria/Melainabacteria group was the predominant phylum in the larvae of P.affinis, while Proteobacteria was the predominant phylum in adult P.affinis and S.farinosa. The number of Order, Family, Genus and Species OTUs in the adult stage of P.affinis was higher than that in the larval stage. The bacterial species richness of adult P.affinis was significantly higher than that of adult S.farinosa. Betaproteobacteria was the predominant class in adult P.affinis, Cyanobacteria in the larvae of P.affinis and Gammaproteobacteria in S.farinosa. The larvae and adult beetles of P.affinis and adult S.farinosahad a low number of unique and shared bacterial OTUs (> 5% relative abundance). The differences in the microbiota indicate possible differences in nutrient assimilation, host taxonomy and other stochastic processes. These findings provide new information to our understanding of the bacteria associated with specialist phytophagous chrysomelid beetles and beetles in general.
  6. Biotic inactivation of the Pseudomonas aeruginosa quinolone signal molecule
    Soh EY, Chhabra SR, Halliday N, Heeb S, Müller C, Birmes FS, et al.
    Environ Microbiol, 2015 Nov;17(11):4352-65.
    PMID: 25809238 DOI: 10.1111/1462-2920.12857
    In Pseudomonas aeruginosa, quorum sensing (QS) regulates the production of secondary metabolites, many of which are antimicrobials that impact on polymicrobial community composition. Consequently, quenching QS modulates the environmental impact of P. aeruginosa. To identify bacteria capable of inactivating the QS signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), a minimal medium containing PQS as the sole carbon source was used to enrich a Malaysian rainforest soil sample. This yielded an Achromobacter xylosoxidans strain (Q19) that inactivated PQS, yielding a new fluorescent compound (I-PQS) confirmed as PQS-derived using deuterated PQS. The I-PQS structure was elucidated using mass spectrometry and nuclear magnetic resonance spectroscopy as 2-heptyl-2-hydroxy-1,2-dihydroquinoline-3,4-dione (HHQD). Achromobacter xylosoxidans Q19 oxidized PQS congeners with alkyl chains ranging from C1 to C5 and also N-methyl PQS, yielding the corresponding 2-hydroxy-1,2-dihydroquinoline-3,4-diones, but was unable to inactivate the PQS precursor HHQ. This indicates that the hydroxyl group at position 3 in PQS is essential and that A. xylosoxidans inactivates PQS via a pathway involving the incorporation of oxygen at C2 of the heterocyclic ring. The conversion of PQS to HHQD also occurred on incubation with 12/17 A. xylosoxidans strains recovered from cystic fibrosis patients, with P. aeruginosa and with Arthrobacter, suggesting that formation of hydroxylated PQS may be a common mechanism of inactivation.
  7. Fulltext Quorum Sensing Inhibitory Activity of Giganteone A from Myristica cinnamomea King against Escherichia coli Biosensors
    Sivasothy Y, Krishnan T, Chan KG, Abdul Wahab SM, Othman MA, Litaudon M, et al.
    Molecules, 2016 Mar 21;21(3):391.
    PMID: 27102164 DOI: 10.3390/molecules21030391
    Malabaricones A-C (1-3) and giganteone A (4) were isolated from the bark of Myristica cinnamomea King. Their structures were elucidated and characterized by means of NMR and MS spectral analyses. These isolates were evaluated for their anti-quorum sensing activity using quorum sensing biosensors, namely Escherichia coli [pSB401] and Escherichia coli [pSB1075], whereby the potential of giganteone A (4) as a suitable anti-quorum sensing agent was demonstrated.
  8. Fulltext Evaluation of Antioxidative and Cytotoxic Activities of Streptomyces pluripotens MUSC 137 Isolated from Mangrove Soil in Malaysia
    Ser HL, Ab Mutalib NS, Yin WF, Chan KG, Goh BH, Lee LH
    Front Microbiol, 2015;6:1398.
    PMID: 26733951 DOI: 10.3389/fmicb.2015.01398
    Streptomyces pluripotens MUSC 137 was isolated from mangrove soil obtained from Tanjung Lumpur, Pahang, Malaysia. We investigated the phylogenetic, genomic, biochemical, and phenotypic characteristics of this strain. Uniquely adapted microorganisms from mangrove habitats have previously yielded compounds of biopharmaceutical interest. In order to examine the bioactivities possessed by the strain, fermentation extract was prepared through solvent extraction method prior to bioactivities screenings. Antioxidant activity was examined via DPPH assay while the cytotoxic effect was assessed by means of examining the activity of the extract against selected human cancer cell lines, namely colon cancer cells (HCT-116, Caco-2, SW480, and HT-29), breast cancer cell (MCF-7), lung cancer cell (A549), prostate cancer cell (DU145), and cervical cancer cell (Ca Ski). The results revealed MUSC 137 possesses significant antioxidant activity and demonstrates cytotoxic effect against several cancer cell lines tested. The results indicated MCF-7 cells were most susceptible to the extract with the lowest IC50 (61.33 ± 17.10 μg/mL), followed by HCT-116 and A549. Additionally, selective index (SI) showed that MUSC 137 extract was less toxic against normal cell lines when compared to MCF-7 and HCT-116 cells. The extract was further subjected to chemical analysis using GC-MS and revealed the presence of deferoxamine and pyrrolizidines related compounds which may account for the antioxidant and cytotoxic properties observed.
  9. Genome sequence of Streptomyces pluripotens MUSC 135(T) exhibiting antibacterial and antioxidant activity
    Ser HL, Tan WS, Ab Mutalib NS, Cheng HJ, Yin WF, Chan KG, et al.
    Mar Genomics, 2015 Dec;24 Pt 3:281-3.
    PMID: 26452302 DOI: 10.1016/j.margen.2015.09.010
    Isolated from intertidal soil, Streptomyces pluripotens MUSC 135(T) produces a broad-spectrum bacteriocin against the pathogens methicillin-resistant Staphylococcus aureus (MRSA) ATCC BAA-44(T), Salmonella typhi ATCC 19430(T) and Aeromonas hydrophila ATCC 7966(T). Along with antibacterial activity, fermentation studies on strain MUSC 135(T) revealed production of antioxidant(s). The high quality draft genome of MUSC 135(T) comprises 7,480,269 bp with G+C content of 70.00%. Through bioinformatics analysis, 72 gene clusters identified in the genome were associated with the production of secondary metabolites, which may shed light on the identity of these bioactive compounds.
  10. Fulltext Streptomyces malaysiense sp. nov.: A novel Malaysian mangrove soil actinobacterium with antioxidative activity and cytotoxic potential against human cancer cell lines
    Ser HL, Palanisamy UD, Yin WF, Chan KG, Goh BH, Lee LH
    Sci Rep, 2016 Apr 13;6:24247.
    PMID: 27072394 DOI: 10.1038/srep24247
    Actinobacteria from the unique intertidal ecosystem of the mangroves are known to produce novel, bioactive secondary metabolites. A novel strain known as MUSC 136(T) (=DSM 100712(T) = MCCC 1K01246(T)) which was isolated from Malaysian mangrove forest soil has proven to be no exception. Assessed by a polyphasic approach, its taxonomy showed a range of phylogenetic and chemotaxonomic properties consistent with the genus of Streptomyces. Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities). The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%. Overall, polyphasic approach studies indicated this strain represents a novel species, for which the name Streptomyces malaysiense sp. nov. is proposed. The potential bioactivities of this strain were explored by means of antioxidant and cytotoxic assays. Intriguingly, MUSC 136(T) exhibited strong antioxidative activities as evaluated by a panel of antioxidant assays. It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels. Chemical analysis of the extract using GC-MS further affirms that the strain produces chemopreventive related metabolites.
  11. Draft genome of amylolytic actinobacterium, Sinomonas humi MUSC 117(T) isolated from intertidal soil
    Ser HL, Tan WS, Cheng HJ, Yin WF, Chan KG, Lee LH
    Mar Genomics, 2015 Dec;24 Pt 3:209-10.
    PMID: 26024612 DOI: 10.1016/j.margen.2015.05.012
    The amylolytic actinobacterium, Sinomonas humi MUSC 117(T) was isolated from intertidal soil from Kuantan, Malaysia. MUSC 117(T) exhibited significant starch hydrolysis activity and was chosen for further analysis. Here we report approximately 4.4 Mbp high quality genome sequence of MUSC 117(T). Availability of the genome sequence will contribute to better understanding for the strain and allow further exploitation of its biotechnological potential.
  12. Streptomyces gilvigriseus sp. nov., a novel actinobacterium isolated from mangrove forest soil
    Ser HL, Zainal N, Palanisamy UD, Goh BH, Yin WF, Chan KG, et al.
    Antonie Van Leeuwenhoek, 2015 Jun;107(6):1369-78.
    PMID: 25863667 DOI: 10.1007/s10482-015-0431-5
    A novel Streptomyces, strain MUSC 26(T), was isolated from mangrove soil at Tanjung Lumpur, Malaysia. The bacterium was observed to be Gram-positive and to form grayish yellow aerial and substrate mycelium on ISP 7 agar. A polyphasic approach was used to study the taxonomy of strain MUSC 26(T), which shows a range of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The cell wall peptidoglycan was determined to contain LL-diaminopimelic acid. The predominant menaquinones were identified as MK-9 (H8) and MK-9(H6). The polar lipids detected were identified as diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylmethylethanolamine and hydroxyphosphatidylmethylethanolamine. The predominant cellular fatty acids (>10.0 %) were identified as anteiso-C15:0 (31.4 %), iso-C16:0 (16.3 %), iso-C15:0 (13.9 %) and anteiso-C17:0 (12.6 %). The cell wall sugars were found to be galactose, glucose, mannose, ribose and rhamnose. These results suggest that MUSC 26(T) should be placed within the genus Streptomyces. Phylogenetic analysis indicated that closely related strains include Streptomyces qinglanensis 172205(T) (96.5 % sequence similarity), S. sodiiphilus YIM 80305(T) (96.5 %) and S. rimosus subsp. rimosus ATCC 10970(T) (96.4 %). DNA-DNA relatedness values between MUSC 26(T) and closely related type strains ranged from 17.0 ± 2.2 to 33.2 ± 5.3 %. Comparison of BOX-PCR fingerprints indicated MUSC 26(T) presents a unique DNA profile. The DNA G+C content was determined to be 74.6 mol%. Based on this polyphasic study of MUSC 26(T), it is concluded that this strain represents a novel species, for which the name Streptomyces gilvigriseus sp. nov. is proposed. The type strain is MUSC 26(T) (=DSMZ 42173(T) = MCCC 1K00504(T)).
  13. Fulltext Streptomyces antioxidans sp. nov., a Novel Mangrove Soil Actinobacterium with Antioxidative and Neuroprotective Potentials
    Ser HL, Tan LT, Palanisamy UD, Abd Malek SN, Yin WF, Chan KG, et al.
    Front Microbiol, 2016;7:899.
    PMID: 27379040 DOI: 10.3389/fmicb.2016.00899
    A novel strain, Streptomyces antioxidans MUSC 164(T) was recovered from mangrove forest soil located at Tanjung Lumpur, Malaysia. The Gram-positive bacterium forms yellowish-white aerial and brilliant greenish yellow substrate mycelium on ISP 2 agar. A polyphasic approach was used to determine the taxonomy status of strain MUSC 164(T). The strain showed a spectrum of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The cell wall peptidoglycan was determined to contain LL-diaminopimelic acid. The predominant menaquinones were identified as MK-9(H6) and MK-9(H8), while the identified polar lipids consisted of aminolipid, diphosphatidylglycerol, glycolipid, hydroxyphosphatidylethanolamine, phospholipid, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol and lipid. The cell wall sugars consist of galactose, glucose and ribose. The predominant cellular fatty acids (>10.0%) were identified as iso-C15: 0 (34.8%) and anteiso-C15: 0(14.0%). Phylogenetic analysis identified that closely related strains for MUSC 164(T) as Streptomyces javensis NBRC 100777(T) (99.6% sequence similarity), Streptomyces yogyakartensis NBRC 100779(T) (99.6%) and Streptomyces violaceusniger NBRC 13459(T) (99.6%). The DNA-DNA relatedness values between MUSC 164(T) and closely related type strains ranged from 23.8 ± 0.3% to 53.1 ± 4.3%. BOX-PCR fingerprints comparison showed that MUSC 164(T) exhibits a unique DNA profile, with DNA G + C content determined to be 71.6 mol%. Based on the polyphasic study of MUSC 164(T), it is concluded that this strain represents a novel species, for which the name Streptomyces antioxidans sp. nov. is proposed. The type strain is MUSC 164(T) (=DSM 101523(T) = MCCC 1K01590(T)). The extract of MUSC 164(T) showed potent antioxidative and neuroprotective activities against hydrogen peroxide. The chemical analysis of the extract revealed that the strain produces pyrazines and phenolic-related compounds that could explain for the observed bioactivities.
  14. Draft Genome Sequence of Mangrove-Derived Streptomyces sp. MUSC 125 with Antioxidant Potential
    Ser HL, Tan WS, Ab Mutalib NS, Yin WF, Chan KG, Goh BH, et al.
    Front Microbiol, 2016;7:1470.
    PMID: 27695452
  15. Fulltext Genome sequence of Streptomyces mangrovisoli MUSC 149T isolated from intertidal sediments
    Ser HL, Tan WS, Ab Mutalib NS, Yin WF, Chan KG, Goh BH, et al.
    Braz J Microbiol, 2017 09 06;49(1):13-15.
    PMID: 28927873 DOI: 10.1016/j.bjm.2017.01.013
    As the largest genus in Actinobacteria family, Streptomyces species have the ability to synthesize numerous compounds of diverse structures with bioactivities. Streptomyces mangrovisoli MUSC 149T was previously isolated as a novel streptomycete from mangrove forest in east coast of Peninsular Malaysia. The high quality draft genome of MUSC 149T comprises 9,165,825bp with G+C content of 72.5%. Through bioinformatics analysis, 21 gene clusters identified in the genome were associated with the production of bioactive secondary metabolites. The presence of these biosynthetic gene clusters in MUSC 149T suggests the potential exploitation of the strain for production of medically important compounds.
  16. Fulltext Genome sequence of Streptomyces gilvigriseus MUSC 26T isolated from mangrove forest
    Ser HL, Tan WS, Mutalib NA, Yin WF, Chan KG, Goh BH, et al.
    Braz J Microbiol, 2018 02 02;49(2):207-209.
    PMID: 29428207 DOI: 10.1016/j.bjm.2017.04.012
    Streptomycetes remain as one of the important sources for bioactive products. Isolated from the mangrove forest, Streptomyces gilvigriseus MUSC 26T was previously characterised as a novel streptomycete. The high quality draft genome of MUSC 26T contained 5,213,277bp with G+C content of 73.0%. Through genome mining, several gene clusters associated with secondary metabolites production were revealed in the genome of MUSC 26T. These findings call for further investigations into the potential exploitation of the strain for production of pharmaceutically important compounds.
  17. Fulltext Focused Review: Cytotoxic and Antioxidant Potentials of Mangrove-Derived Streptomyces
    Ser HL, Tan LT, Law JW, Chan KG, Duangjai A, Saokaew S, et al.
    Front Microbiol, 2017;8:2065.
    PMID: 29163380 DOI: 10.3389/fmicb.2017.02065
    Human life expectancy is rapidly increasing with an associated increasing burden of chronic diseases, such as neurodegenerative diseases and cancer. However, there is limited progress in finding effective treatment for these conditions. For this reason, members of the genus Streptomyces have been explored extensively over the past decades as these filamentous bacteria are highly efficient in producing bioactive compounds with human health benefits. Being ubiquitous in nature, streptomycetes can be found in both terrestrial and marine environments. Previously, two Streptomyces strains (MUSC 137T and MUM 256) isolated from mangrove sediments in Peninsular Malaysia demonstrated potent antioxidant and cytotoxic activities against several human cancer cell lines on bioactivity screening. These results illustrate the importance of streptomycetes from underexplored regions aside from the terrestrial ecosystem. Here we provide the insights and significance of Streptomyces species in the search of anticancer and/or chemopreventive agents and highlight the impact of next generation sequencing on drug discovery from the Streptomyces arsenal.
  18. Fulltext Fermentation Conditions that Affect Clavulanic Acid Production in Streptomyces clavuligerus: A Systematic Review
    Ser HL, Law JW, Chaiyakunapruk N, Jacob SA, Palanisamy UD, Chan KG, et al.
    Front Microbiol, 2016;7:522.
    PMID: 27148211 DOI: 10.3389/fmicb.2016.00522
    The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO), from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g., olive oil, corn oil) could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.). Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus.
  19. Fulltext Presence of antioxidative agent, Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro- in newly isolated Streptomyces mangrovisoli sp. nov
    Ser HL, Palanisamy UD, Yin WF, Abd Malek SN, Chan KG, Goh BH, et al.
    Front Microbiol, 2015;6:854.
    PMID: 26347733 DOI: 10.3389/fmicb.2015.00854
    A novel Streptomyces, strain MUSC 149(T) was isolated from mangrove soil. A polyphasic approach was used to study the taxonomy of MUSC 149(T), which shows a range of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The diamino acid of the cell wall peptidoglycan was LL-diaminopimelic acid. The predominant menaquinones were identified as MK9(H8) and MK9(H6). Phylogenetic analysis indicated that closely related strains include Streptomyces rhizophilus NBRC 108885(T) (99.2% sequence similarity), S. gramineus NBRC 107863(T) (98.7%) and S. graminisoli NBRC 108883(T) (98.5%). The DNA-DNA relatedness values between MUSC 149(T) and closely related type strains ranged from 12.4 ± 3.3% to 27.3 ± 1.9%. The DNA G + C content was determined to be 72.7 mol%. The extract of MUSC 149(T) exhibited strong antioxidant activity and chemical analysis reported identification of an antioxidant agent, Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-. These data showed that metabolites of MUSC 149(T) shall be useful as preventive agent against free-radical associated diseases. Based on the polyphasic study of MUSC 149(T), the strain merits assignment to a novel species, for which the name S. mangrovisoli sp. nov. is proposed. The type strain is MUSC 149(T) (=MCCC 1K00699(T)=DSM 100438(T)).
  20. Genome sequence of Roseivirga sp. strain D-25 and its potential applications from the genomic aspect
    Selvaratnam C, Thevarajoo S, Ee R, Chan KG, Bennett JP, Goh KM, et al.
    Mar Genomics, 2016 Apr 20.
    PMID: 27107724 DOI: 10.1016/j.margen.2016.04.004
    Roseivirga sp. strain D-25 is an aerobic marine bacterium isolated from seawater collected from Desaru beach, Malaysia. To date, the genus Roseivirga consists of only four species with no genome sequence reported. Here, we present the genome sequence of Roseivirga sp. strain D-25 (=KCTC 42709=DSM 101709), with a genome size of approximately 4.08Mbp and G+C content of 39.18%. Genome sequence analysis of strain D-25 revealed the presence of genes related to petroleum hydrocarbon degradation, 2,4,6-trinitrotoluene detoxification, heavy metals bioremediation and production of carotenoids, which shed light on the potential application of this strain.
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