Displaying publications 61 - 80 of 123 in total

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  1. High Diversity of Bacterial Communities in Developmental Stages of Bactrocera carambolae (Insecta: Tephritidae) Revealed by Illumina MiSeq Sequencing of 16S rRNA Gene
    Yong HS, Song SL, Chua KO, Lim PE
    Curr Microbiol, 2017 Sep;74(9):1076-1082.
    PMID: 28642971 DOI: 10.1007/s00284-017-1287-x
    Bactrocera carambolae is a highly polyphagous fruit pest of agricultural importance. This study reports the bacterial communities associated with the developmental stages of B. carambolae. The microbiota of the developmental stages were investigated by targeted 16S rRNA gene (V3-V4 region) sequencing using the Illumina MiSeq. At 97% similarity, there were 19 bacterial phyla and unassigned bacteria, comprising 39 classes, 86 orders, 159 families and 311 genera. The bacterial composition varied among the specimens of developmental stage and across developmental stages as well as exuviae. Four phyla of bacteria (with relative abundance of ≥1% in at least one specimen)-Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria-were recovered from the larva, pupa, adult stages and exuviae. Proteobacteria was the predominant phylum in all the developmental stages as well as the exuviae. Enterobacteriaceae (Proteobacteria) was the predominant family in the adult flies while the family [Weeksellaceae] (Bacteroidetes) was predominant in the larval and pupal stages. Among the genera occurring in more than one developmental stage of B. carambolae, Erwinia was more abundant in the larval stage, Halomonas more abundant in adult female, Stenotrophomonas more abundant in adult male, and Chryseobacterium more abundant in the larval and pupal stages. The results indicate transmission of bacteria OTUs from immatures to the newly emerged adults, and from exuviae to the environment.
    Matched MeSH terms: DNA, Ribosomal/genetics
  2. Fulltext Diversity, enumeration, and isolation of Arcobacter spp. in the giant abalone, Haliotis gigantea
    Mizutani Y, Iehata S, Mori T, Oh R, Fukuzaki S, Tanaka R
    Microbiologyopen, 2019 10;8(10):e890.
    PMID: 31168933 DOI: 10.1002/mbo3.890
    Arcobacter have been frequently detected in and isolated from bivalves, but there is very little information on the genus Arcobacter in the abalone, an important fishery resource. This study aimed to investigate the genetic diversity and abundance of bacteria from the genus Arcobacter in the Japanese giant abalone, Haliotis gigantea, using molecular methods such as Arcobacter-specific clone libraries and fluorescence in situ hybridization (FISH). Furthermore, we attempted to isolate the Arcobacter species detected. Twelve genotypes of clones were obtained from Arcobacter-specific clone libraries. These sequences are not classified with any other known Arcobacter species including pathogenic Arcobacter spp., A. butzleri, A. skirrowii, and A. cryaerophilus, commonly isolated or detected from bivalves. From the FISH analysis, we observed that ARC94F-positive cells, presumed to be Arcobacter, accounted for 6.96 ± 0.72% of all EUB338-positive cells. In the culture method, three genotypes of Arcobacter were isolated from abalones. One genotype had a similarity of 99.2%-100.0% to the 16S rRNA gene of Arcobacter marinus, while the others showed only 93.3%-94.3% similarity to other Arcobacter species. These data indicate that abalones carry Arcobacter as a common bacterial genus which includes uncultured species.
    Matched MeSH terms: DNA, Ribosomal/genetics
  3. Amycolatopsis thermophila sp. nov. and Amycolatopsis viridis sp. nov., thermophilic actinomycetes isolated from arid soil
    Zucchi TD, Tan GYA, Goodfellow M
    Int J Syst Evol Microbiol, 2012 Jan;62(Pt 1):168-172.
    PMID: 21378137 DOI: 10.1099/ijs.0.029256-0
    The taxonomic positions of two thermophilic actinomycetes isolated from an arid Australian soil sample were established based on an investigation using a polyphasic taxonomic approach. The organisms had chemical and morphological properties typical of members of the genus Amycolatopsis and formed distinct phyletic lines in the Amycolatopsis methanolica 16S rRNA subclade. The two organisms were distinguished from one another and from the type strains of related species of the genus Amycolatopsis using a range of phenotypic properties. Based on the combined genotypic and phenotypic data, it is proposed that the two isolates be classified in the genus Amycolatopsis as Amycolatopsis thermophila sp. nov. (type strain GY088(T)=NCIMB 14699(T)=NRRL B-24836(T)) and Amycolatopsis viridis sp. nov. (type strain GY115(T)=NCIMB 14700(T)=NRRL B-24837(T)).
    Matched MeSH terms: DNA, Ribosomal/genetics
  4. Fulltext Psychrotolerant Mesorhizobium sp. Isolated from Temperate and Cold Desert Regions Solubilizes Potassium and Produces Multiple Plant Growth Promoting Metabolites
    Baba ZA, Hamid B, Sheikh TA, Alotaibi SH, El Enshasy HA, Ansari MJ, et al.
    Molecules, 2021 Sep 23;26(19).
    PMID: 34641302 DOI: 10.3390/molecules26195758
    Soil potassium (K) supplement depends intensively on the application of chemical fertilizers, which have substantial harmful environmental effects. However, some bacteria can act as inoculants by converting unavailable and insoluble K forms into plant-accessible forms. Such bacteria are an eco-friendly approach for enhancing plant K absorption and consequently reducing utilization of chemical fertilization. Therefore, the present research was undertaken to isolate, screen, and characterize the K solubilizing bacteria (KSB) from the rhizosphere soils of northern India. Overall, 110 strains were isolated, but only 13 isolates showed significant K solubilizing ability by forming a halo zone on solid media. They were further screened for K solubilizing activity at 0 °C, 1 °C, 3 °C, 5 °C, 7 °C, 15 °C, and 20 °C for 5, 10, and 20 days. All the bacterial isolates showed mineral K solubilization activity at these different temperatures. However, the content of K solubilization increased with the upsurge in temperature and period of incubation. The isolate KSB (Grz) showed the highest K solubilization index of 462.28% after 48 h of incubation at 20 °C. The maximum of 23.38 µg K/mL broth was solubilized by the isolate KSB (Grz) at 20 °C after 20 days of incubation. Based on morphological, biochemical, and molecular characterization (through the 16S rDNA approach), the isolate KSB (Grz) was identified as Mesorhizobium sp. The majority of the strains produced HCN and ammonia. The maximum indole acetic acid (IAA) (31.54 µM/mL) and cellulase (390 µM/mL) were produced by the isolate KSB (Grz). In contrast, the highest protease (525.12 µM/mL) and chitinase (5.20 µM/mL) activities were shown by standard strain Bacillus mucilaginosus and KSB (Gmr) isolate, respectively.
    Matched MeSH terms: DNA, Ribosomal/genetics
  5. Molecular evidence of Sarcocystis nesbitti in water samples of Tioman Island, Malaysia
    Shahari S, Tengku-Idris TI, Fong MY, Lau YL
    Parasit Vectors, 2016 11 23;9(1):598.
    PMID: 27881179
    BACKGROUND: Sarcocystis are intracellular protozoan parasites that are characterised by their ability to invade muscle tissue and form intramuscular sarcocysts. A muscular sarcocystosis outbreak was reported by travellers returning from Tioman Island in 2011 and 2012 where Sarcocystis nesbitti was identified as the main cause. The source of the S. nesbitti that was involved has remained elusive, although water is hypothesised to be the main cause of transmission. A surveillance study was therefore undertaken in the northern regions of Tioman Island to identify the source of S. nesbitti by screening rivers, water tanks, wells and seawater.

    METHODS: Water samples were collected from rivers, water tanks, wells and seawater on Tioman Island over the course of April to October 2015. Water samples were indirectly screened for Sarcocystis species by obtaining sediment from respective water sources. PCR amplification of the 18S rRNA gene region was conducted to identify positive samples. Microscopy was used in an attempt to reappraise PCR results, but no sporocysts were detected in any of the samples.

    RESULTS: A total of 157 water samples were obtained and 19 were positive for various Sarcocystis species. Through BLASTn and phylogenetic analysis, these species were found to be S. singaporensis, S. nesbitti, Sarcocystis sp. YLL-2013 and one unidentified Sarcocystis species.

    CONCLUSIONS: This is the first positive finding of S. nesbitti in water samples on Tioman Island, which was found in a water tank and in river water samples. This finding supports the hypothesis that water was a potential medium for the transmission of S. nesbitti during the outbreak. This will potentially identify areas in which preventive measures can be taken to prevent future outbreaks.

    Matched MeSH terms: DNA, Ribosomal/genetics
  6. The life cycle of Thelohanellus kitauei (Myxozoa: Myxosporea) infecting common carp (Cyprinus carpio) involves aurantiactinomyxon in Branchiura sowerbyi
    Zhao D, Borkhanuddin MH, Wang W, Liu Y, Cech G, Zhai Y, et al.
    Parasitol Res, 2016 Nov;115(11):4317-4325.
    PMID: 27492197
    Thelohanellus kitauei is a freshwater myxosporean parasite causing intestinal giant cystic disease of common carp. To clarify the life cycle of T. kitauei, we investigated the oligochaete populations in China and Hungary. This study confirms two distinct aurantiactinomyxon morphotypes (Aurantiactinomyxon type 1 and Aurantiactinomyxon type 2) from Branchiura sowerbyi as developmental stages of the life cycle of T. kitauei. The morphological characteristics and DNA sequences of these two types are described here. Based on 18S rDNA sequence analysis, Aurantiactinomyxon type 1 (2048 bp) and Aurantiactinomyxon type 2 (2031 bp) share 99.2-99.4 %, 99.8-100 % similarity to the published sequences of T. kitauei, respectively. The 18S rDNA sequences of these two aurantiactinomyxon morphotypes share 99.4 % similarity, suggesting intraspecific variation within the taxon, possibly due to geographic origin. Phylogenetic analyses demonstrate the two aurantiactinomyxon types clustered with T. kitauei. Regardless, based on 18S rDNA synonymy, it is likely that Aurantiactinomyxon type 1 and 2 are conspecific with T. kitauei. This is the fourth elucidated two-host life cycle of Thelohanellus species and the first record of T. kitauei in Europe.
    Matched MeSH terms: DNA, Ribosomal/genetics
  7. Vibrio coralliirubri sp. nov., a new species isolated from mucus of red coral (Corallium rubrum) collected at Procida island, Italy
    Poli A, Romano I, Mastascusa V, Buono L, Orlando P, Nicolaus B, et al.
    Antonie Van Leeuwenhoek, 2018 Jul;111(7):1105-1115.
    PMID: 29299771 DOI: 10.1007/s10482-017-1013-5
    Strain Corallo1T was isolated from mucus of red coral (Corallium rubrum) at Punta Pizzaco (Procida island, Naples, Italy). It was characterised as a Gram-stain negative, motile, rod-shaped bacterium. Strain Corallo1T was found to show positive responses for cytochrome-c oxidase, catalase, reduction of nitrate and nitrite, β-galactosidase activity and hydrolysis of starch, xylan, peptone, Tween 40, Tween 80 and casein. Strain Corallo1T was found to be mesophilic, neutrophilic to alkalophilic and slightly halophilic. According to analysis of the almost-complete 16S rRNA gene, strain Corallo1T is closely related to Vibrio celticus (100% sequence similarity), Vibrio gigantis (100%), Vibrio crassostreae (99.7%), Vibrio artabrorum (99.7%) and Vibrio pomeroyi (99.6%). MLSA of five housekeeping genes (atpA, pyrH, recA, rpoA and rpoD) was performed to refine the phylogenetic relationships of strain Corallo1T. A draft genome sequence of strain Corallo1T was obtained. The DNA G+C content of this strain was determined to be 44.5 mol %. The major cellular fatty acids of strain Corallo1T are C16:1, n-C16:0 and C18:1, and the major isoprenoid ubiquinone is Q8. ANI indexes, in silico estimations of DDH values and wet lab DDH values demonstrated that strain Corallo1T represents an independent genomospecies. Based on a polyphasic taxonomic characterisation, strain Corallo1T is concluded to represent a novel species of the genus Vibrio, for which the name Vibrio coralliirubri sp. nov. is proposed. The type strain is Corallo1T (= DSM 27495T = CIP 110630T).
    Matched MeSH terms: DNA, Ribosomal/genetics
  8. Fulltext Satellite DNA in Paphiopedilum subgenus Parvisepalum as revealed by high-throughput sequencing and fluorescent in situ hybridization
    Lee YI, Yap JW, Izan S, Leitch IJ, Fay MF, Lee YC, et al.
    BMC Genomics, 2018 Aug 02;19(1):578.
    PMID: 30068293 DOI: 10.1186/s12864-018-4956-7
    BACKGROUND: Satellite DNA is a rapidly diverging, largely repetitive DNA component of many eukaryotic genomes. Here we analyse the evolutionary dynamics of a satellite DNA repeat in the genomes of a group of Asian subtropical lady slipper orchids (Paphiopedilum subgenus Parvisepalum and representative species in the other subgenera/sections across the genus). A new satellite repeat in Paphiopedilum subgenus Parvisepalum, SatA, was identified and characterized using the RepeatExplorer pipeline in HiSeq Illumina reads from P. armeniacum (2n = 26). Reconstructed monomers were used to design a satellite-specific fluorescent in situ hybridization (FISH) probe. The data were also analysed within a phylogenetic framework built using the internal transcribed spacer (ITS) sequences of 45S nuclear ribosomal DNA.

    RESULTS: SatA comprises c. 14.5% of the P. armeniacum genome and is specific to subgenus Parvisepalum. It is composed of four primary monomers that range from 230 to 359 bp and contains multiple inverted repeat regions with hairpin-loop motifs. A new karyotype of P. vietnamense (2n = 28) is presented and shows that the chromosome number in subgenus Parvisepalum is not conserved at 2n = 26, as previously reported. The physical locations of SatA sequences were visualised on the chromosomes of all seven Paphiopedilum species of subgenus Parvisepalum (2n = 26-28), together with the 5S and 45S rDNA loci using FISH. The SatA repeats were predominantly localisedin the centromeric, peri-centromeric and sub-telocentric chromosome regions, but the exact distribution pattern was species-specific.

    CONCLUSIONS: We conclude that the newly discovered, highly abundant and rapidly evolving satellite sequence SatA is specific to Paphiopedilum subgenus Parvisepalum. SatA and rDNA chromosomal distributions are characteristic of species, and comparisons between species reveal that the distribution patterns generate a strong phylogenetic signal. We also conclude that the ancestral chromosome number of subgenus Parvisepalum and indeed of all Paphiopedilum could be either 2n = 26 or 28, if P. vietnamense is sister to all species in the subgenus as suggested by the ITS data.

    Matched MeSH terms: DNA, Ribosomal/genetics
  9. Fulltext Using metabarcoding to compare the suitability of two blood-feeding leech species for sampling mammalian diversity in North Borneo
    Drinkwater R, Schnell IB, Bohmann K, Bernard H, Veron G, Clare E, et al.
    Mol Ecol Resour, 2019 Jan;19(1):105-117.
    PMID: 30225935 DOI: 10.1111/1755-0998.12943
    The application of high-throughput sequencing (HTS) for metabarcoding of mixed samples offers new opportunities in conservation biology. Recently, the successful detection of prey DNA from the guts of leeches has raised the possibility that these, and other blood-feeding invertebrates, might serve as useful samplers of mammals. Yet little is known about whether sympatric leech species differ in their feeding preferences, and whether this has a bearing on their relative suitability for monitoring local mammalian diversity. To address these questions, we collected spatially matched samples of two congeneric leech species Haemadipsa picta and Haemadipsa sumatrana from lowland rainforest in Borneo. For each species, we pooled ~500 leeches into batches of 10 individuals, performed PCR to target a section of the mammalian 16S rRNA locus and undertook sequencing of amplicon libraries using an Illumina MiSeq. In total, we identified sequences from 14 mammalian genera, spanning nine families and five orders. We found greater numbers of detections, and higher diversity of OTUs, in H. picta compared with H. sumatrana, with rodents only present in the former leech species. However, comparison of samples from across the landscape revealed no significant difference in mammal community composition between the leech species. We therefore suggest that H. picta is the more suitable iDNA sampler in this degraded Bornean forest. We conclude that the choice of invertebrate sampler can influence the detectability of different mammal groups and that this should be accounted for when designing iDNA studies.
    Matched MeSH terms: DNA, Ribosomal/genetics
  10. Fulltext Impact of logging and forest conversion to oil palm plantations on soil bacterial communities in Borneo
    Lee-Cruz L, Edwards DP, Tripathi BM, Adams JM
    Appl Environ Microbiol, 2013 Dec;79(23):7290-7.
    PMID: 24056463 DOI: 10.1128/AEM.02541-13
    Tropical forests are being rapidly altered by logging and cleared for agriculture. Understanding the effects of these land use changes on soil bacteria, which constitute a large proportion of total biodiversity and perform important ecosystem functions, is a major conservation frontier. Here we studied the effects of logging history and forest conversion to oil palm plantations in Sabah, Borneo, on the soil bacterial community. We used paired-end Illumina sequencing of the 16S rRNA gene, V3 region, to compare the bacterial communities in primary, once-logged, and twice-logged forest and land converted to oil palm plantations. Bacteria were grouped into operational taxonomic units (OTUs) at the 97% similarity level, and OTU richness and local-scale α-diversity showed no difference between the various forest types and oil palm plantations. Focusing on the turnover of bacteria across space, true β-diversity was higher in oil palm plantation soil than in forest soil, whereas community dissimilarity-based metrics of β-diversity were only marginally different between habitats, suggesting that at large scales, oil palm plantation soil could have higher overall γ-diversity than forest soil, driven by a slightly more heterogeneous community across space. Clearance of primary and logged forest for oil palm plantations did, however, significantly impact the composition of soil bacterial communities, reflecting in part the loss of some forest bacteria, whereas primary and logged forests did not differ in composition. Overall, our results suggest that the soil bacteria of tropical forest are to some extent resilient or resistant to logging but that the impacts of forest conversion to oil palm plantations are more severe.
    Matched MeSH terms: DNA, Ribosomal/genetics
  11. Fulltext Dimorphic male scutal patterns and upper-eye facets of Simulium mirum n. sp. (Diptera: Simuliidae) from Malaysia
    Takaoka H, Low VL, Sofian-Azirun M, Otsuka Y, Ya'cob Z, Chen CD, et al.
    Parasit Vectors, 2016;9:136.
    PMID: 26961508 DOI: 10.1186/s13071-016-1393-9
    A species of Simulium in the Simulium melanopus species-group of the subgenus Simulium (formerly misidentified as S. laterale Edwards from Sabah and Sarawak, Malaysia) is suspected to have dimorphic male scutal color patterns linked with different numbers of upper-eye facets. This study aimed to confirm whether or not these two forms of adult males represent a single species.
    Matched MeSH terms: DNA, Ribosomal/genetics
  12. Fulltext Isolation and Characterization of an Atypical Metschnikowia sp. Strain from the Skin Scraping of a Dermatitis Patient
    Kuan CS, Ismail R, Kwan Z, Yew SM, Yeo SK, Chan CL, et al.
    PLoS One, 2016;11(6):e0156119.
    PMID: 27280438 DOI: 10.1371/journal.pone.0156119
    A yeast-like organism was isolated from the skin scraping sample of a stasis dermatitis patient in the Mycology Unit Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. The isolate produced no pigment and was not identifiable using chromogenic agar and API 20C AUX. The fungus was identified as Metschnikowia sp. strain UM 1034, which is close to that of Metschnikowia drosophilae based on ITS- and D1/D2 domain-based phylogenetic analysis. However, the physiology of the strain was not associated to M. drosophilae. This pathogen exhibited low sensitivity to all tested azoles, echinocandins, 5-flucytosine and amphotericin B. This study provided insight into Metschnikowia sp. strain UM 1034 phenotype profiles using a Biolog phenotypic microarray (PM). The isolate utilized 373 nutrients of 760 nutrient sources and could adapt to a broad range of osmotic and pH environments. To our knowledge, this is the first report of the isolation of Metschnikowia non-pulcherrima sp. from skin scraping, revealing this rare yeast species as a potential human pathogen that may be misidentified as Candida sp. using conventional methods. Metschnikowia sp. strain UM 1034 can survive in flexible and diverse environments with a generalist lifestyle.
    Matched MeSH terms: DNA, Ribosomal/genetics
  13. Microbacterium gilvum sp. nov., isolated from civet faeces
    Chen X, Li QY, Li GD, Xu FJ, Jiang Y, Han L, et al.
    Antonie Van Leeuwenhoek, 2016 Sep;109(9):1177-83.
    PMID: 27260265 DOI: 10.1007/s10482-016-0718-1
    A novel aerobic, non-motile, Gram-positive, rod-shaped actinobacterium, designated YIM 100951(T), was isolated from the faeces of civets (Viverra zibetha) living in the National Nature Protect Region in Selangor, Malaysia. Strain YIM 100951(T) shows high similarities with Microbacterium barkeri DSM 20145(T) (97.6 %), Microbacterium oryzae MB10(T) (97.3 %), Microbacterium lemovicicum ViU22(T) (97.1 %) and Microbacterium indicum BBH6(T) (97.0 %) based on their 16S rRNA genes. However, phylogenetic analysis showed that strain YIM 100951(T) formed a clade with Microbacterium halotolerans YIM 70130(T) (96.7 %), Microbacterium populi 10-107-8(T) (96.7 %) and Microbacterium sediminis YLB-01(T) (96.9 %). DNA-DNA hybridization was carried out between strains YIM 100951(T) and M. barkeri DSM 20145(T), the result showed a value of 23.2 ± 4.5 %. In addition, some of the physiological, biochemical and chemotaxonomic characteristics of strain YIM 100951(T) are different from the closely related strains. Thus, we suggest that strain YIM 100951(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium gilvum sp. nov. is proposed. The type strain is YIM 100951(T) (=DSM 26235(T) = CCTCC AB 2012971(T)).
    Matched MeSH terms: DNA, Ribosomal/genetics
  14. Molecular diversity of the ammonia-oxidizing bacteria community in disused tin-mining ponds located within Kampar, Perak, Malaysia
    Sow SL, Khoo G, Chong LK, Smith TJ, Harrison PL, Ong HK
    World J Microbiol Biotechnol, 2014 Feb;30(2):757-66.
    PMID: 24078113
    Disused tin-mining ponds make up a significant amount of water bodies in Malaysia particularly at the Kinta Valley in the state of Perak where tin-mining activities were the most extensive, and these abundantly available water sources are widely used in the field of aquaculture and agriculture. However, the natural ecology and physicochemical conditions of these ponds, many of which have been altered due to secondary post-mining activities, remains to be explored. As ammonia-oxidizing bacteria (AOB) are directly related to the nutrient cycles of aquatic environments and are useful bioindicators of environmental variations, the focus of this study was to identify AOBs associated with disused tin-mining ponds that have a history of different secondary activities in comparison to ponds which were left untouched and remained as part of the landscape. The 16S rDNA gene was used to detect AOBs in the sediment and water sampled from the three types of disused mining ponds, namely ponds without secondary activity, ponds that were used for lotus cultivation and post-aquaculture ponds. When the varying pond types were compared with the sequence and phylogenetic analysis of the AOB clone libraries, both Nitrosomonas and Nitrosospira-like AOB were detected though Nitrosospira spp. was seen to be the most ubiquitous AOB as it was present in all ponds types. However, AOBs were not detected in the sediments of idle ponds. Based on rarefaction analysis and diversity indices, the disused mining pond with lotus culture indicated the highest richness of AOBs. Canonical correspondence analysis indicated that among the physicochemical properties of the pond sites, TAN and nitrite were shown to be the main factors that influenced the community structure of AOBs in these disused tin-mining ponds.
    Matched MeSH terms: DNA, Ribosomal/genetics
  15. Fulltext Unusual long-chain N-acyl homoserine lactone production by and presence of quorum quenching activity in bacterial isolates from diseased tilapia fish
    Chang CY, Koh CL, Sam CK, Chan XY, Yin WF, Chan KG
    PLoS One, 2012;7(8):e44034.
    PMID: 22952864 DOI: 10.1371/journal.pone.0044034
    Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.
    Matched MeSH terms: DNA, Ribosomal/genetics
  16. Fulltext Molecular characterization of clinical isolates of Aeromonas species from Malaysia
    Puthucheary SD, Puah SM, Chua KH
    PLoS One, 2012;7(2):e30205.
    PMID: 22383958 DOI: 10.1371/journal.pone.0030205
    BACKGROUND: Aeromonas species are common inhabitants of aquatic environments giving rise to infections in both fish and humans. Identification of aeromonads to the species level is problematic and complex due to their phenotypic and genotypic heterogeneity.

    METHODOLOGY/PRINCIPAL FINDINGS: Aeromonas hydrophila or Aeromonas sp were genetically re-identified using a combination of previously published methods targeting GCAT, 16S rDNA and rpoD genes. Characterization based on the genus specific GCAT-PCR showed that 94 (96%) of the 98 strains belonged to the genus Aeromonas. Considering the patterns obtained for the 94 isolates with the 16S rDNA-RFLP identification method, 3 clusters were recognised, i.e. A. caviae (61%), A. hydrophila (17%) and an unknown group (22%) with atypical RFLP restriction patterns. However, the phylogenetic tree constructed with the obtained rpoD sequences showed that 47 strains (50%) clustered with the sequence of the type strain of A. aquariorum, 18 (19%) with A. caviae, 16 (17%) with A. hydrophila, 12 (13%) with A. veronii and one strain (1%) with the type strain of A. trota. PCR investigation revealed the presence of 10 virulence genes in the 94 isolates as: lip (91%), exu (87%), ela (86%), alt (79%), ser (77%), fla (74%), aer (72%), act (43%), aexT (24%) and ast (23%).

    CONCLUSIONS/SIGNIFICANCE: This study emphasizes the importance of using more than one method for the correct identification of Aeromonas strains. The sequences of the rpoD gene enabled the unambiguous identication of the 94 Aeromonas isolates in accordance with results of other recent studies. Aeromonas aquariorum showed to be the most prevalent species (50%) containing an important subset of virulence genes lip/alt/ser/fla/aer. Different combinations of the virulence genes present in the isolates indicate their probable role in the pathogenesis of Aeromonas infections.

    Matched MeSH terms: DNA, Ribosomal/genetics*
  17. 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: DNA, Ribosomal/genetics
  18. Myxozoan infection of the Malaysian mahseer, Tor tambroides, of Tasik Kenyir Reservoir, Malaysia: description of a new species Myxobolus tambroides sp.n
    Székely C, Shaharom F, Cech G, Mohamed K, Zin NA, Borkhanuddin MH, et al.
    Parasitol Res, 2012 Oct;111(4):1749-56.
    PMID: 22782473
    Tor tambroides, a common and appreciated cyprinid fish of the Tasik Kenyir water reservoir in Malaysia, is one of the species selected for propagation. This fish was first successfully propagated in Malaysia by the Department of Agriculture, Sarawak, Malaysia, and the breeding program continued throughout the country. The gills were frequently infected by a Myxobolus species to be described as Myxobolus tambroides sp. n. The small, 50 to 70 μm, round plasmodia of this species is located intralamellarly. Plasmodia were filled with pyriform myxospores, 9.9 and 7.4 μm wide. In sutural view, the caudal end of the myxospores had a distinctive valvular groove, parallel with the suture. Plasmodia caused deformations on the affected and the neighbouring gill lamellae. The 18S rDNA sequence of M. tambroides sp.n. did not show a close relationship with any other Myxobolus spp., represented in the GenBank. This might be an emerging parasite likely to impact the propagation of this fish.
    Matched MeSH terms: DNA, Ribosomal/genetics
  19. Fulltext Polyhydroxyalkanoate production by antarctic soil bacteria isolated from Casey Station and Signy Island
    Goh YS, Tan IK
    Microbiol Res, 2012 Apr 20;167(4):211-9.
    PMID: 21945102 DOI: 10.1016/j.micres.2011.08.002
    Polyhydroxyalkanoate (PHA) is a family of biopolymers produced by some bacteria and is accumulated intracellularly as carbon and energy storage material. Fifteen PHA-producing bacterial strains were identified from bacteria isolated from Antarctic soils collected around Casey Station (66°17'S, 110°32'E) and Signy Island (60°45'S, 45°36'W). Screening for PHA production was carried out by incubating the isolates in PHA production medium supplemented with 0.5% (w/v) sodium octanoate or glucose. 16S rRNA gene sequence analysis revealed that the isolated PHA-producing strains were mainly Pseudomonas spp. and a few were Janthinobacterium spp. All the isolated Pseudomonas strains were able to produce medium-chain-length (mcl) PHA using fatty acids as carbon source, while some could also produce mcl-PHA by using glucose. The Janthinobacterium strains could only utilize glucose to produce polyhydroxybutyrate (PHB). A Pseudomonas isolate, UMAB-40, accumulated PHA up to 48% cell dry mass when utilizing fatty acids as carbon source. This high accumulation occurred at between 5°C and 20°C, then decreased with increasing temperatures. Highly unsaturated mcl-PHA was produced by UMAB-40 from glucose. Such characteristics may be associated with the ability of UMAB-40 to survive in the cold.
    Matched MeSH terms: DNA, Ribosomal/genetics
  20. Enhancement of thermostable lipase production by a genotypically identified extremophilic Bacillus subtilis NS 8 in a continuous bioreactor
    Olusesan AT, Azura LK, Abubakar F, Mohamed AK, Radu S, Manap MY, et al.
    J. Mol. Microbiol. Biotechnol., 2011 Apr;20(2):105-15.
    PMID: 21422764 DOI: 10.1159/000324535
    Bacillus strain NS 8, a lipase-producing bacterium isolated from a Malaysian hot spring, is able to tolerate a broad range of temperature and pH, which makes it beneficial for this study. It generated PCR products with molecular weight of 1,532 bp, and the 16S rRNA sequence analysis identified it as Bacillus subtilis with accession number AB110598. It showed a 71% similarity index with B. subtilis using Biolog Microstation System. Its lipase production was optimized using a shake flask system by changing the physical (agitation speed, pH and temperature) and nutritional (nitrogen, carbon and minerals) factors. The most suitable combination of the basal medium for lipase production was 2.5% olive oil (carbon), 1.5% peptone (nitrogen), 0.1% MgSO(4) (mineral) at an optimum temperature of 50°C, pH 7.5 and 150 rpm agitation, giving an enzyme yield of 4.23 U/ml. Statistical optimization using response surface methodology was carried out. An optimum lipase production of 5.67 U/ml was achieved when olive oil concentration of 3%, peptone 2%, MgSO(4)·7H(2)O 0.2% and an agitation rate of 200 rpm were combined. Lipase production was further carried out inside a 2-liter bioreactor, which yielded an enzyme activity of 14.5 U/ml after 15 h of incubation.
    Matched MeSH terms: DNA, Ribosomal/genetics
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