Displaying publications 81 - 100 of 209 in total

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  1. Molecular characterization of Antarctic actinobacteria and screening for antimicrobial metabolite production
    Lee LH, Cheah YK, Mohd Sidik S, Ab Mutalib NS, Tang YL, Lin HP, et al.
    World J Microbiol Biotechnol, 2012 May;28(5):2125-37.
    PMID: 22806035 DOI: 10.1007/s11274-012-1018-1
    The present study aimed to isolate actinobacteria from soil samples and characterized them using molecular tools and screened their secondary metabolites for antimicrobial activities. Thirty-nine strains from four different location of Barrientos Island, Antarctica using 12 types of isolation media was isolated. The isolates were preceded to screening of secondary metabolites for antimicrobial and antifungal activities. Using high-throughput screening methods, 38% (15/39) of isolates produced bioactive metabolites. Approximately 18% (7/39), 18% (7/39), 10% (4/39) and 2.5% (1/39) of isolates inhibited growth of Candida albicans ATCC 10231(T), Staphylococcus aurues ATCC 51650(T), methicillin-resistant Staphylococcus aurues (MRSA) ATCC BAA-44(T) and Pseudomonas aeruginosa ATCC 10145(T), respectively. Molecular characterization techniques like 16S rRNA analysis, Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR), Random amplified polymorphic DNA (RAPD) and composite analyses were used to characterize the actinobacteria strains. Analysis of 16S rRNA sequences is still one of the most powerful methods to determine higher taxonomic relationships of Actinobacteria. Both RAPD and ERIC-PCR fingerprinting have shown good discriminatory capability but RAPD proved to be better in discriminatory power than ERIC-PCR. Our results demonstrated that composite analysis of both fingerprinting generally increased the discrimination ability and generated best clustering for actinobacteria strains in this study.
    Matched MeSH terms: Soil Microbiology
  2. Mitigation of petroleum-hydrocarbon-contaminated hazardous soils using organic amendments: A review
    Hoang SA, Sarkar B, Seshadri B, Lamb D, Wijesekara H, Vithanage M, et al.
    J Hazard Mater, 2021 08 15;416:125702.
    PMID: 33866291 DOI: 10.1016/j.jhazmat.2021.125702
    The term "Total petroleum hydrocarbons" (TPH) is used to describe a complex mixture of petroleum-based hydrocarbons primarily derived from crude oil. Those compounds are considered as persistent organic pollutants in the terrestrial environment. A wide array of organic amendments is increasingly used for the remediation of TPH-contaminated soils. Organic amendments not only supply a source of carbon and nutrients but also add exogenous beneficial microorganisms to enhance the TPH degradation rate, thereby improving the soil health. Two fundamental approaches can be contemplated within the context of remediation of TPH-contaminated soils using organic amendments: (i) enhanced TPH sorption to the exogenous organic matter (immobilization) as it reduces the bioavailability of the contaminants, and (ii) increasing the solubility of the contaminants by supplying desorbing agents (mobilization) for enhancing the subsequent biodegradation. Net immobilization and mobilization of TPH have both been observed following the application of organic amendments to contaminated soils. This review examines the mechanisms for the enhanced remediation of TPH-contaminated soils by organic amendments and discusses the influencing factors in relation to sequestration, bioavailability, and subsequent biodegradation of TPH in soils. The uncertainty of mechanisms for various organic amendments in TPH remediation processes remains a critical area of future research.
    Matched MeSH terms: Soil Microbiology
  3. Microtetraspora malaysiensis sp. nov., isolated from Malaysian primary dipterocarp forest soil
    Nakajima Y, Ho CC, Kudo T
    J Gen Appl Microbiol, 2003 Jun;49(3):181-9.
    PMID: 12949699
    The taxonomic position of three actinomycete strains isolated from Malaysian soil was established by using a polyphasic approach. The isolates formed chains composed of four spores on the tip of sporophores branching from the aerial mycelium, and their chemotaxonomic properties were common to those of members of the family Streptosporangiaceae. These phenotypic properties as well as a phylogenetic analysis based on 16S rRNA gene sequences indicated that they should be classified in the genus Microtetraspora. The three isolates showed a unique pattern of cultural, physiological and biochemical properties that distinguished them from previously described species of the genus Microtetraspora. The isolates showed more than 72% DNA relatedness to each other, but only 58% or less relatedness to any previously described species. On the basis of the data presented, a new species of the genus Microtetraspora, Microtetraspora malaysiensis, is proposed. The type strain of the new species is strain H47-7(T) (=JCM 11278(T)=DSM 44579(T)).
    Matched MeSH terms: Soil Microbiology*
  4. Fulltext Microbial Contributions for Rice Production: From Conventional Crop Management to the Use of 'Omics' Technologies
    Doni F, Suhaimi NSM, Mispan MS, Fathurrahman F, Marzuki BM, Kusmoro J, et al.
    Int J Mol Sci, 2022 Jan 10;23(2).
    PMID: 35054923 DOI: 10.3390/ijms23020737
    Rice, the main staple food for about half of the world's population, has had the growth of its production stagnate in the last two decades. One of the ways to further improve rice production is to enhance the associations between rice plants and the microbiome that exists around, on, and inside the plant. This article reviews recent developments in understanding how microorganisms exert positive influences on plant growth, production, and health, focusing particularly on rice. A variety of microbial species and taxa reside in the rhizosphere and the phyllosphere of plants and also have multiple roles as symbiotic endophytes while living within plant tissues and even cells. They alter the morphology of host plants, enhance their growth, health, and yield, and reduce their vulnerability to biotic and abiotic stresses. The findings of both agronomic and molecular analysis show ways in which microorganisms regulate the growth, physiological traits, and molecular signaling within rice plants. However, many significant scientific questions remain to be resolved. Advancements in high-throughput multi-omics technologies can be used to elucidate mechanisms involved in microbial-rice plant associations. Prospectively, the use of microbial inoculants and associated approaches offers some new, cost-effective, and more eco-friendly practices for increasing rice production.
    Matched MeSH terms: Soil Microbiology
  5. Microbacterium mangrovi sp. nov., an amylolytic actinobacterium isolated from mangrove forest soil
    Lee LH, Azman AS, Zainal N, Eng SK, Mutalib NA, Yin WF, et al.
    Int J Syst Evol Microbiol, 2014 Oct;64(Pt 10):3513-3519.
    PMID: 25056298 DOI: 10.1099/ijs.0.062414-0
    Strain MUSC 115(T) was isolated from mangrove soil of the Tanjung Lumpur river in the state of Pahang, Peninsular Malaysia. Cells of this strain stained Gram-positive and were non-spore-forming, short rods that formed yellowish-white colonies on different agar media. The taxonomy of strain MUSC 115(T) was studied by a polyphasic approach, and the organism showed a range of phylogenetic and chemotaxonomic properties consistent with those of the genus Microbacterium. The cell-wall peptidoglycan was of type B2β, containing the amino acids ornithine, alanine, glycine, glutamic acid and homoserine. The muramic acid was of the N-glycolyl form. The predominant menaquinones detected were MK-12, MK-13 and MK-11. The polar lipids consisted of phosphatidylglycerol, phosphoglycolipid, diphosphatidylglycerol, two unidentified lipids, three unidentified phospholipids and four unidentified glycolipids. The major fatty acids of the cell membrane were anteiso-C15:0 and anteiso-C17:0. The whole-cell sugars detected were ribose, glucose, mannose and galactose. Based on the 16S rRNA gene sequence, strain MUSC 115(T) showed the highest sequence similarity to Microbacterium immunditiarum SK 18(T) (98.1%), M. ulmi XIL02(T) (97.8%) and M. arborescens DSM 20754(T) (97.5%) and lower sequence similarity to strains of other species of the genus Microbacterium. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 24%) between strain MUSC 115(T) and the type strains of closely related species. Furthermore, BOX-PCR fingerprint comparison also indicated that strain MUSC 115(T) represented a unique DNA profile. The DNA G+C content determined was 70.9 ± 0.7 mol%, which is lower than that of M. immunditiarum SK 18(T). Based on the combination of genotypic and phenotypic data, it is proposed that strain MUSC 115(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium mangrovi sp. nov. is proposed. The type strain is MUSC 115(T) ( = MCCC 1K00251(T) = DSM 28240(T) = NBRC 110089(T)).
    Matched MeSH terms: Soil Microbiology*
  6. Metagenomics profiling for assessing microbial diversity in both active and closed landfills
    Zainun MY, Simarani K
    Sci Total Environ, 2018 Mar;616-617:269-278.
    PMID: 29117585 DOI: 10.1016/j.scitotenv.2017.10.266
    The municipal landfill is an example of human-made environment that harbours some complex diversity of microorganism communities. To evaluate this complexity, the structures of bacterial communities in active (operational) and closed (non-operational) landfills in Malaysia were analysed with culture independent metagenomics approaches. Several points of soil samples were collected from 0 to 20cm depth and were subjected to physicochemical test, such as temperature, pH, and moisture content. In addition, the heavy metal contamination was determined by using ICPMS. The bacterial enumeration was examined on nutrient agar (NA) plates aerobically at 30°C. The soil DNA was extracted, purified and amplified prior to sequence the 16S rRNA gene for statistical and bioinformatics analyses. As a result, the average of bacteria for the closed landfill was higher compared to that for the active landfill at 9.16×107 and 1.50×107, respectively. The higher bacterial OTUs sequenced was also recorded in closed landfills compared to active landfill i.e. 6625 and 4552 OTUs respectively. The data from both landfills showed that the predominant phyla belonged to Proteobacteria (55.7%). On average, Bacteroidetes was the second highest phylum followed by Firmicutes for the active landfill. While the phyla for communities in closed landfill were dominated by phyla from Acidobacteria and Actinobacteria. There was also Euryarchaeota (Archaea) which became a minor phylum that was detected in active landfill, but almost completely absent in closed landfill. As such, the composition of bacterial communities suggests some variances between the bacterial communities found in active and closed landfills. Thus, this study offers new clues pertaining to bacterial diversity pattern between the varied types of landfills studied.
    Matched MeSH terms: Soil Microbiology*
  7. Fulltext Melioidosis: Clinical impact and public health threat in the tropics
    Perumal Samy R, Stiles BG, Sethi G, Lim LHK
    PLoS Negl Trop Dis, 2017 May;11(5):e0004738.
    PMID: 28493905 DOI: 10.1371/journal.pntd.0004738
    This review briefly summarizes the geographical distribution and clinical impact of melioidosis, especially in the tropics. Burkholderia pseudomallei (a gram-negative bacterium) is the major causative agent for melioidosis, which is prevalent in Singapore, Malaysia, Thailand, Vietnam, and Northern Australia. Melioidosis patients are increasingly being recognized in other parts of the world. The bacteria are intrinsically resistant to many antimicrobial agents, but prolonged treatment, especially with combinations of antibiotics, may be effective. Despite therapy, the overall case fatality rate of septicemia in melioidosis remains significantly high. Intracellular survival of the bacteria within macrophages may progress to chronic infections, and about 10% of patients suffer relapses. In the coming decades, melioidosis will increasingly afflict travelers throughout many global regions. Clinicians managing travelers returning from the subtropics or tropics with severe pneumonia or septicemia should consider acute melioidosis as a differential diagnosis. Patients with open skin wounds, diabetes, or chronic renal disease are at higher risk for melioidosis and should avoid direct contact with soil and standing water in endemic regions. Furthermore, there are fears that B. pseudomallei may be used as a biological weapon. Technological advancements in molecular diagnostics and antibiotic therapy are improving the disease outcomes in endemic areas throughout Asia. Research and development efforts on vaccine candidates against melioidosis are ongoing.
    Matched MeSH terms: Soil Microbiology
  8. Melioidosis in Malaysia. IV. Intensive ecological study of Carey Island, Selangor, for Pseudomonas pseudomallei
    Strauss JM, Ellison DW, Gan E, Jason S, Marcarelli JL, Rapmund G
    Med J Malaya, 1969 Dec;24(2):94-100.
    PMID: 4244150
    Matched MeSH terms: Soil Microbiology
  9. Melioidosis in Malaysia. II. Distribution of Pseudomonas pseudomallei in soil and surface water
    Strauss JM, Groves MG, Mariappan M, Ellison DW
    Am J Trop Med Hyg, 1969 Sep;18(5):698-702.
    PMID: 5810797
    Matched MeSH terms: Soil Microbiology*
  10. Melioidosis in Malaysia. I. A method for isolation of Pseudomonas pseudomallei from soil and surface water
    Ellison DW, Baker HJ, Mariappan M
    Am J Trop Med Hyg, 1969 Sep;18(5):694-7.
    PMID: 5810796
    Matched MeSH terms: Soil Microbiology*
  11. Melioidosis antibodies in Commonwealth soldiers
    Thin RN
    Lancet, 1976 Jan 3;1(7949):31-3.
    PMID: 54528 DOI: 10.1016/s0140-6736(76)92922-6
    Titres of melioidosis haemagglutinating antibodies of 1/40 or more were found in 18 of 905 British, Australian, and New Zealand soldiers serving in West Malaysia. Previous mild unsuspected melioidosis seemed to be responsible for these positive titres, which were more common in men exposed to surface water at work and during recreation. This accords with the current view that soil and surface water is the normal habitat of Pseudomonas pseudomallei, the causal organism. Pyrexia of unknown origin after arriving in Malaysia was significantly more common in men with titres of 1/40 or more than in the remainder. It is suggested that mild melioidosis may present as pyrexia of unknown origin. Pyrexias of unknown origin should be investigated vigorously in patients who are in or who have visited endemic areas.
    Matched MeSH terms: Soil Microbiology
  12. Fulltext Mangrove derived Streptomyces sp. MUM265 as a potential source of antioxidant and anticolon-cancer agents
    Tan LT, Chan KG, Pusparajah P, Yin WF, Khan TM, Lee LH, et al.
    BMC Microbiol, 2019 02 13;19(1):38.
    PMID: 30760201 DOI: 10.1186/s12866-019-1409-7
    BACKGROUND: Colon cancer is the third most commonly diagnosed cancer worldwide, with a commensurately high mortality rate. The search for novel antioxidants and specific anticancer agents which may inhibit, delay or reverse the development of colon cancer is thus an area of great interest; Streptomyces bacteria have been demonstrated to be a source of such agents.

    RESULTS: The extract from Streptomyces sp. MUM265- a strain which was isolated and identified from Kuala Selangor mangrove forest, Selangor, Malaysia- was analyzed and found to exhibit antioxidant properties as demonstrated via metal-chelating ability as well as superoxide anion, DPPH and ABTS radical scavenging activities. This study also showed that MUM265 extract demonstrated cytotoxicity against colon cancer cells as evidenced by the reduced cell viability of Caco-2 cell line. Treatment with MUM265 extract induced depolarization of mitochondrial membrane potential and accumulation of subG1 cells in cell cycle analysis, suggesting that MUM265 exerted apoptosis-inducing effects on Caco-2 cells.

    CONCLUSION: These findings indicate that mangrove derived Streptomyces sp. MUM265 represents a valuable bioresource of bioactive compounds for the future development of chemopreventive agents, with particular promise suggested for treatment of colon cancer.

    Matched MeSH terms: Soil Microbiology
  13. Malaysian mosquitocidal soil bacterium (Bacillus thuringiensis) strains with selective hemolytic and lectin activity against human and rat erythrocytes
    Nadarajah VD, Chai SH, Mohammed SM, Chan KK, Kanakeswary K
    Southeast Asian J. Trop. Med. Public Health, 2006 Jan;37(1):67-78.
    PMID: 16771215
    The objective of this study is to determine the role of carbohydrates on the toxic effect of parasporal inclusion proteins isolated from Malaysian mosquitocidal Bacillus thuringiensis (Bt) strains on erythrocytes (human and rat). Dose response analyses on the effect of these parasporal inclusions on human and rat erythrocytes suggest that toxin action is selective depending on bacterial strains and source of erythrocytes. Results from this study suggest Bt toxin is a lectin which recognizes specific plasma membrane glycoconjugate receptor(s) with a terminal residue of either D-mannose (Man), N-acetyl-D-galactosamine (GalNAc), N-acetyl-D-glucosamine (GlcNAc) or even a combination of these monosaccharides.
    Matched MeSH terms: Soil Microbiology*
  14. Luteipulveratus halotolerans sp. nov., an actinobacterium (Dermacoccaceae) from forest soil
    Juboi H, Basik AA, Shamsul SSG, Arnold P, Schmitt EK, Sanglier JJ, et al.
    Int J Syst Evol Microbiol, 2015 Nov;65(11):4113-4120.
    PMID: 26303235 DOI: 10.1099/ijsem.0.000548
    The taxonomic position of an actinobacterium strain, C296001T, isolated from a soil sample collected in Sarawak, Malaysia, was established using a polyphasic approach. Phylogenetically, strain C296001T was closely associated with the genus Luteipulveratus and formed a distinct monophyletic clade with the only described species, Luteipulveratus mongoliensis NBRC 105296T. The 16S rRNA gene sequence similarity between strain C296001T and L. mongoliensis was 98.7 %. DNA-DNA hybridization results showed that the relatedness of strain C296001T to L. mongoliensis was only 21.5 %. The DNA G+C content of strain C296001T was 71.7 mol%. Using a PacBio RS II system, whole genome sequences for strains C296001T and NBRC 105296T were obtained. The genome sizes of 4.5 Mbp and 5.4 Mbp determined were similar to those of other members of the family Dermacoccaceae. The cell-wall peptidoglycan contained lysine, alanine, aspartic acid, glutamic acid and serine, representing the peptidoglycan type A4α l-Lys-l-Ser-d-Asp. The major menaquinones were MK-8(H4), MK-8 and MK-8(H2). Phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol and phosphoglycolipid were the polar lipids, while the whole-cell sugars were glucose, fucose and lesser amounts of ribose and galactose. The major fatty acids were iso-C16 : 0, anteiso-C17 : 0, iso-C16 : 1 H, anteiso-C17 : 1ω9c, iso-C18 : 0 and 10-methyl C17 : 0. Chemotaxonomic analyses showed that C296001T had typical characteristics of members of the genus Luteipulveratus, with the main differences occurring in phenotypic characteristics. On the basis of the phenotypic and chemotaxonomic evidence, it is proposed that strain C296001T be classified as a representative of a novel species in the genus Luteipulveratus, for which the name Luteipulveratus halotolerans sp. nov. is recommended. The type strain is C296001T ( = ATCC TSD-4T = JCM 30660T).
    Matched MeSH terms: Soil Microbiology*
  15. Locally isolated yeasts from Malaysia: identification, phylogenetic study and characterization
    Oslan SN, Salleh AB, Rahman RN, Basri M, Chor AL
    Acta Biochim. Pol., 2012;59(2):225-9.
    PMID: 22577620
    Yeasts are a convenient platform for many applications. They have been widely used as the expression hosts. There is a need to have a new yeast expression system to contribute the molecular cloning demands. Eight yeast isolates were screened from various environment sources and identified through ribosomal DNA (rDNA) Internal Transcribed Spacer (ITS). Full sequence of the rDNA ITS region for each isolate was BLASTed and phylogenetic study was constructed by using MEGA4. Among the isolates, isolate WB from 'ragi' (used to ferment carbohydrates) could be identified as a new species in order Saccharomycetales according to rDNA ITS region, morphology and biochemical tests. Isolate SO (from spoiled orange), RT (rotten tomato) and RG (different type of 'ragi') were identified as Pichia sp. Isolates R1 and R2, S4 and S5 (from the surrounding of a guava tree) were identified as Issatchenkia sp. and Hanseniaspora sp., respectively. Geneticin, 50 µg/mL, was determined to be the antibiotic marker for all isolates excepted for isolates RT and SO which used 500 µg/mL and 100 µg/mL Zeocin, respectively. Intra-extracellular proteins were screened for lipolytic activity at 30°C and 70°C. Thermostable lipase activity was detected in isolates RT and R1 with 0.6 U/mg and 0.1 U/mg, respectively. In conclusion, a new yeast-vector system for isolate WB can be developed by using phleomycin or geneticin as the drugs resistance marker. Moreover, strains RT and R1 can be investigated as a novel source of a thermostable lipase.
    Matched MeSH terms: Soil Microbiology
  16. Lithological constraints on resource economies shape the mycorrhizal composition of a Bornean rain forest
    Weemstra M, Peay KG, Davies SJ, Mohamad M, Itoh A, Tan S, et al.
    New Phytol, 2020 10;228(1):253-268.
    PMID: 32436227 DOI: 10.1111/nph.16672
    Arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) produce contrasting plant-soil feedbacks, but how these feedbacks are constrained by lithology is poorly understood. We investigated the hypothesis that lithological drivers of soil fertility filter plant resource economic strategies in ways that influence the relative fitness of trees with AMF or EMF symbioses in a Bornean rain forest containing species with both mycorrhizal strategies. Using forest inventory data on 1245 tree species, we found that although AMF-hosting trees had greater relative dominance on all soil types, with declining lithological soil fertility EMF-hosting trees became more dominant. Data on 13 leaf traits and wood density for a total of 150 species showed that variation was almost always associated with soil type, whereas for six leaf traits (structural properties; carbon, nitrogen, phosphorus ratios, nitrogen isotopes), variation was also associated with mycorrhizal strategy. EMF-hosting species had slower leaf economics than AMF-hosts, demonstrating the central role of mycorrhizal symbiosis in plant resource economies. At the global scale, climate has been shown to shape forest mycorrhizal composition, but here we show that in communities it depends on soil lithology, suggesting scale-dependent abiotic factors influence feedbacks underlying the relative fitness of different mycorrhizal strategies.
    Matched MeSH terms: Soil Microbiology
  17. Fulltext Linking prokaryotic community composition to carbon biogeochemical cycling across a tropical peat dome in Sarawak, Malaysia
    Dom SP, Ikenaga M, Lau SYL, Radu S, Midot F, Yap ML, et al.
    Sci Rep, 2021 Mar 19;11(1):6416.
    PMID: 33742002 DOI: 10.1038/s41598-021-81865-6
    Tropical peat swamp forest is a global store of carbon in a water-saturated, anoxic and acidic environment. This ecosystem holds diverse prokaryotic communities that play a major role in nutrient cycling. A study was conducted in which a total of 24 peat soil samples were collected in three forest types in a tropical peat dome in Sarawak, Malaysia namely, Mixed Peat Swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests to profile the soil prokaryotic communities through meta 16S amplicon analysis using Illumina Miseq. Results showed these ecosystems were dominated by anaerobes and fermenters such as Acidobacteria, Proteobacteria, Actinobacteria and Firmicutes that cover 80-90% of the total prokaryotic abundance. Overall, the microbial community composition was different amongst forest types and depths. Additionally, this study highlighted the prokaryotic communities' composition in MPS was driven by higher humification level and lower pH whereas in ABt and ABg, the less acidic condition and higher organic matter content were the main factors. It was also observed that prokaryotic diversity and abundance were higher in the more oligotrophic ABt and ABg forest despite the constantly waterlogged condition. In MPS, the methanotroph Methylovirgula ligni was found to be the major species in this forest type that utilize methane (CH4), which could potentially be the contributing factor to the low CH4 gas emissions. Aquitalea magnusonii and Paraburkholderia oxyphila, which can degrade aromatic compounds, were the major species in ABt and ABg forests respectively. This information can be advantageous for future study in understanding the underlying mechanisms of environmental-driven alterations in soil microbial communities and its potential implications on biogeochemical processes in relation to peatland management.
    Matched MeSH terms: Soil Microbiology*
  18. Light-activated cytotoxic compounds from Malaysian microorganisms for photodynamic therapy of cancer
    Kamal N, Sabaratnam V, Abdullah N, Ho AS, Teo SH, Lee HB
    Antonie Van Leeuwenhoek, 2009 Feb;95(2):179-88.
    PMID: 19125347 DOI: 10.1007/s10482-008-9301-8
    Photodynamic therapy (PDT) is a promising cancer treatment which involves activation of a photosensitizing drug with light to produce reactive oxygen species that kill tumors without causing damage to unirradiated normal tissues. To date, only Photofrin, Foscan and Levulan have been approved for clinical treatment of cancer. Tropical habitats such as those found in Malaysia are attractive sources of new therapeutic compounds as tremendous chemical diversity is found in a large number of plants, animals, marine- and micro-organisms. In our screening program for novel photosensitizers from nature, colorful strains of fungi (from Aspergillus and Penicillium genus) and bacteria (including actinomycetes and photosynthetic bacteria) were collected from various habitats in Peninsular Malaysia, such as coastal soil, peat soil, marine sponges and wastewater ponds. Methanolic extracts from a total of 85 different species were evaluated with a short-term cell viability assay for photo-cytotoxicity, where a promyelocytic leukemia cell-line, HL60 incubated with 20 microg/ml of extracts was irradiated with 9.6 J/cm(2) of a broad spectrum light. Two of these extracts, one from Rhodobacter sphaeroides (PBUM003) and one from Rhodopseudomonas palustris (PBUM001) showed moderate to strong photo-cytotoxicity. Subsequent bioassay guided isolation of the PBUM001 extract yielded known photosensitisers that are based on bacteriochlorophyll-a by comparing their molecular weight data, HPLC profiles and UV-vis absorption spectra with literature values, thereby demonstrating the validity of our screening approach.
    Matched MeSH terms: Soil Microbiology*
  19. Leptospira kmetyi sp. nov., isolated from an environmental source in Malaysia
    Slack AT, Khairani-Bejo S, Symonds ML, Dohnt MF, Galloway RL, Steigerwalt AG, et al.
    Int J Syst Evol Microbiol, 2009 Apr;59(Pt 4):705-8.
    PMID: 19329592 DOI: 10.1099/ijs.0.002766-0
    A single Leptospira strain (designated Bejo-Iso9(T)) was isolated from a soil sample taken in Johor, Malaysia. The isolate showed motility and morphology typical of the genus Leptospira under dark-field microscopy. Cells were found to be 10-13 microm in length and 0.2 microm in diameter, with a wavelength of 0.5 microm and an amplitude of approximately 0.2 microm. Phenotypically, strain Bejo-Iso9(T) grew in Ellinghausen-McCullough-Johnson-Harris medium at 13, 30 and 37 degrees C, and also in the presence of 8-azaguanine. Serologically, strain Bejo-Iso9(T) produced titres towards several members of the Tarassovi serogroup, but was found to be serologically unique by cross-agglutinin absorption test and thus represented a novel serovar. The proposed name for this serovar is Malaysia. Phylogenetic analysis of 16S rRNA gene sequences placed this novel strain within the radiation of the genus Leptospira, with sequence similarities within the range 90.4-99.5% with respect to recognized Leptospira species. DNA-DNA hybridization against the three most closely related Leptospira species was used to confirm the results of the 16S rRNA gene sequence analysis. The G+C content of the genome of strain Bejo-Iso9(T) was 36.2 mol%. On the basis of phenotypic, serological and phylogenetic data, strain Bejo-Iso9(T) represents a novel species of the genus Leptospira, for which the name Leptospira kmetyi sp. nov. is proposed. The type strain is Bejo-Iso9(T) (=WHO LT1101(T)=KIT Bejo-Iso9(T)).
    Matched MeSH terms: Soil Microbiology*
  20. Langkocyclines: novel angucycline antibiotics from Streptomyces sp. Acta 3034(*)
    Kalyon B, Tan GY, Pinto JM, Foo CY, Wiese J, Imhoff JF, et al.
    J Antibiot (Tokyo), 2013 Oct;66(10):609-16.
    PMID: 23820614 DOI: 10.1038/ja.2013.53
    Langkocyclines A1-A3 and B1 and B2, five new angucycline antibiotics produced by Streptomyces sp. Acta 3034, were detected in the course of our HPLC-diode array screening. The producing strain was isolated from the rhizospheric soil of a Clitorea sp. collected from Burau Bay, Langkawi, Malaysia, and was characterized by morphological, physiological and chemotaxonomic features in addition to 16S ribosomal RNA gene sequence information. Strain Acta 3034 is closely related to Streptomyces psammoticus NBRC 13971(T) and Streptomyces lanatus NBRC 12787(T). Langkocyclines consist of an angular tetracyclic benz[a]anthracene skeleton and hydrolyzable O-glycosidic sugar moieties. The yellow-colored A-type langkocyclines differ in their aglycon from the blue-lilac-colored B-type langkocyclines. The A-type langkocycline aglycon is identical to that of aquayamycin and urdamycin A. The chemical structures of the langkocyclines were elucidated by HR-MS, 1D and 2D NMR experiments. They are biologically active against Gram-positive bacteria and exhibit a moderate antiproliferative activity against various human tumor cell lines.
    Matched MeSH terms: Soil Microbiology
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