Journal of Microbiology

Review

MINIREVIEW] Toxin-producing Cyanobacteria in Freshwater: A Review of the Problems, Impact on Drinking Water Safety, and Efforts for Protecting Public Health: Melissa Y. Cheung , Song Liang , Jiyoung Lee; J. Microbiol. 2013;51(1):1-10. Published online March 2, 2013; DOI: https://doi.org/10.1007/s12275-013-2549-3

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Abstract: Cyanobacteria have adapted to survive in a variety of environments and have been found globally. Toxin-producing cyanobacterial harmful algal blooms (CHABs) have been increasing in frequency worldwide and pose a threat to drinking and recreational water. In this study, the prevalence, impact of CHABs and mitigation efforts were reviewed, focusing on the Lake Erie region and Ohio’s inland lakes that have been impacted heavily as an example so that the findings can be transferrable to other parts of the world that face the similar problems due to the CHABs in their freshwater environments. This paper provides a basic introduction to CHABs and their toxins as well as an overview of public health implications including exposure routes, health effects, and drinking water issues, algal bloom advisory practices in Ohio, toxin measurements results in Ohio public water supplies, and mitigation efforts.

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

Effects of Phosphate Addition on Biofilm Bacterial Communities and Water Quality in Annular Reactors Equipped with Stainless Steel and Ductile Cast Iron Pipes: Hyun-Jung Jang , Young-June Choi , Hee-Myong Ro , Jong-Ok Ka; J. Microbiol. 2012;50(1):17-28. Published online February 27, 2012; DOI: https://doi.org/10.1007/s12275-012-1040-x

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Abstract: The impact of orthophosphate addition on biofilm formation and water quality was studied in corrosion-resistant stainless steel (STS) pipe and corrosion-susceptible ductile cast iron (DCI) pipe using cultivation and culture-independent approaches. Sample coupons of DCI pipe and STS pipe were installed in annular reactors, which were operated for 9 months under hydraulic conditions similar to a domestic plumbing system. Addition of 5 mg/L of phosphate to the plumbing systems, under low residual chlorine conditions, promoted a more significant growth of biofilm and led to a greater rate reduction of disinfection by-products in DCI pipe than in STS pipe. While the level of THMs (trihalomethanes) increased under conditions of low biofilm concentration, the levels of HAAs (halo acetic acids) and CH (chloral hydrate) decreased in all cases in proportion to the amount of biofilm. It was also observed that chloroform, the main species of THM, was not readily decomposed biologically and decomposition was not proportional to the biofilm concentration; however, it was easily biodegraded after the addition of phosphate. Analysis of the 16S rDNA sequences of 102 biofilm isolates revealed that Proteobacteria (50%) was the most frequently detected phylum, followed by Firmicutes (10%) and Actinobacteria (2%), with 37% of the bacteria unclassified. Bradyrhizobium was the dominant genus on corroded DCI pipe, while Sphingomonas was predominant on non-corroded STS pipe. Methylobacterium and Afipia were detected only in the reactor without added phosphate. PCR-DGGE analysis showed that the diversity of species in biofilm tended to increase when phosphate was added regardless of the pipe material, indicating that phosphate addition upset the biological stability in the plumbing systems.

Methylobacterium dankookense sp. nov., Isolated from Drinking Water: Si-Won Lee , Hyun-Woo Oh , Kang-Hyun Lee , Tae-Young Ahn; J. Microbiol. 2009;47(6):716-720. Published online February 4, 2010; DOI: https://doi.org/10.1007/s12275-009-0126-6

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Abstract: A pink-pigmented bacterium, designated SW08-7T was isolated from the drinking water of a water purifier. Cells were Gram-negative, rod-shaped, strictly aerobic, and non-spore-forming. It grew optimally at 25°C, pH 6~7. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain SW08-7T belongs to the genus Methylobacterium. The highest 16S rRNA gene sequence similarities were found to Methylobacterium mesophilicum JCM 2829T (96.9%), Methylobacterium brachiatum B0021T (96.9%), Methylobacterium phyllosphaerae CBMB27T (96.6%), Methylobacterium radiotolerans JCM 2831T (96.6%), and Methylobacterium hispanicum GP34T (96.5%). DNA-DNA hybridization experiment revealed low-level (28.5%) of DNA- DNA relatedness between strain SW08-7T and Methylobacterium hispanicum. The genomic DNA G+C content was 68.9 mol% and the major isoprenoid quinone was Q-10. The major cellular fatty acid of strain SW08-7T was C18:1 ω7c (79.8±2.1%). Results of phylogenetic, phenotypic, and biochemical analyses revealed that strain SW08-7T could be classified as representing a novel species of genus Methylobacterium, for which the name Methylobacterium dankookense sp. nov. is proposed. The type strain is SW08-7T (=KCTC 22512T =DSM 22415T).

Molecular Characterization of Antibiotic Resistant Escherichia coli Strains Isolated from Tap and Spring Waters in a Coastal Region in Turkey: Osman Birol Ozgumus , Elif Celik-Sevim , Sengul Alpay-Karaoglu , Cemal Sandalli , Ali Sevim; J. Microbiol. 2007;45(5):379-387.; DOI: https://doi.org/2600 [pii]

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Abstract: A hundred and seventeen antibiotic-resistant Escherichia coli strains were isolated from public tap and spring waters which were polluted by fecal coliforms. There were no significant differences between two water sources as to the coliform pollution level (p> 0.05). All E. coli isolates were detected to be resistant to one or more antibiotics tested. Nearly 42% of the isolates showed multiresistant phenotype. Three (2.5%) of these isolates contained class 1 integron. Sequencing analysis of variable regions of the class 1 integrons showed two gene cassette arrays, dfr1-aadA1 and dhfrA17-aadA5. Resistance to ampicillin, tetracycline or trimethoprim-sulfamethoxazole was transferable according to the results of conjugation experiments. The rate of tetracycline resistance was 15%. tet(A)-mediated tetracycline resistance was widespread among tetracycline-resistant E. coli isolates. Genotyping by BOX-polymerase chain reaction (BOX-PCR) showed that some of the strains were epidemiologically related. This is the first report on the prevalence and characterization of class 1 integron-containing E. coli isolates of environmental origin in Turkey.

Development of a Virus Concentration Method and its Application for the Detection of Noroviruses in Drinking Water in China: Junyi Liu , Qingping Wu , Xiaoxia Kou; J. Microbiol. 2007;45(1):48-52.; DOI: https://doi.org/2492 [pii]

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Abstract: A new procedure for the concentration of nonoviruses from water samples has been developed. This procedure (calcium flocculation-citrate dissolution method) uses the following steps: virus flocculation formed by treatment with 1 M CaCl2 and 1 M Na2HPO4, virus release by sodium citrate dissolution (0.3 M Na citrate, pH 3.5), and virus re-concentration by ultrafiltration. When reverse transcription (RT)-PCR was performed after the procedure, the overall detection sensitivity for seeded noroviruses in a one liter drinking water sample was as low as 1 RT-PCR unit, which is equal to a 10-6 dilution of the virus sample. This approach showed at least a 5-fold-higher sensitivity than the current method with its three steps of adsorption-elution-concentration. The newly developed procedure was used to test different brands of bottled drinking water from China for putative contamination with noroviruses. A total of 144 samples were analyzed; all of the samples were negative for norovirus specific nucleic acids.

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