Plant debris are hotbeds for pathogenic bacteria on recreational sandy beaches.

On recreational sandy beaches, there are guidelines for the management of bacterial pollution in coastal waters regarding untreated sewage, urban wastewater, and industrial wastewater. However, terrestrial plant debris on coastal beaches can be abundant especially after floods and whilst it has rarely been considered a concern, the bacterial population associated with this type of pollution from the viewpoint of public health has not been adequately assessed. In this study, microbes associated with plant debris drifting onto Kizaki Beach in Japan were monitored for 8 months throughout the rainy season, summer, typhoon season, and winter. Here we show that faecal-indicator bacteria in the plant debris and sand under the debris were significantly higher than the number of faecal bacteria in the sand after a 2015 typhoon. When we focused on specific pathogenic bacteria, Brevundimonas vesicularis and Pseudomonas alcaligenes were commonly detected only in the plant debris and sand under the debris during the survey period. The prompt removal of plant debris would therefore help create safer beaches.

The involvement of α-proteobacteria Phenylobacterium in maintaining the dominance of toxic Microcystis blooms in Lake Taihu, China.

Lake Taihu in China has suffered serious harmful cyanobacterial blooms for decades. The algal blooms threaten the ecological sustainability, drinking water safety, and human health. Although the roles of abiotic factors (such as water temperature and nutrient loading) in promoting Microcystis blooms have been well studied, the importance of biotic factors (e.g. bacterial community) in promoting and meditating Microcystis blooms remains unclear. In this study, we investigated the ecological dynamics of bacterial community, the ratio of toxic Microcystis, as well as microcystin in Lake Taihu. High-throughput 16S rRNA sequencing and principal component analysis (PCA) revealed that the bacteria community compositions (BCCs) clustered into three groups, the partitioning of which corresponded to that of groups according to the toxic profiles (the ratio of toxic Microcystis to total Microcystis, and the microcystin concentrations) of the samples. Further Spearman's correlation network showed that the α-proteobacteria Phenylobacterium strongly positively correlated with the toxic profiles. Subsequent laboratory chemostats experiments demonstrated that three Phenylobacterium strains promoted the dominance of the toxic Microcystis aeruginosa PCC7806 when co-culturing with the non-toxic PCC7806 mcyB- mutant. Taken together, our data suggested that the α-proteobacteria Phenylobacterium may play a vital role in the maintenance of toxic Microcystis dominance in Lake Taihu.

Discrimination of heavy metal acclimated environmental strains by chemometric analysis of FTIR spectra.

Heavy metal acclimated bacteria are profoundly the preferred choice for bioremediation studies. Bacteria get acclimated to toxic concentrations of heavy metals by induction of specific enzymes and genetic selection favoring new metabolic abilities leading to activation of one or several of resistance mechanisms creating bacterial populations with differences in resistance profile and/or level. Therefore, to use in bioremediation processes, it is important to discriminate acclimated bacterial populations and choose a more resistant strain. In this study, we discriminated heavy metal acclimated bacteria by using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and multivariate analysis methods namely Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA) and Soft Independent Modeling of Class Analogy (SIMCA). Two acclimation methods, acute and gradual, were used which cause differences in molecular changes resulting in bacterial populations with different molecular and resistance profiles. Brevundimonas sp., Gordonia sp., and Microbacterium oxydans were exposed to the toxic concentrations of Cd (30 µg/ml) or Pb (90 µg/ml) by using broth medium as a growth media. Our results revealed that PCA and HCA clearly discriminated the acute-acclimated, gradual-acclimated, and control bacteria from each other in protein, carbohydrate, and whole spectral regions. Furthermore, we classified acclimated (acute and gradual) and control bacteria more accurately by using SIMCA with 99.9% confidence. This study demonstrated that heavy metal acclimated and control group bacteria can be discriminated by using chemometric analysis of FTIR spectra in a powerful, cost-effective, and handy way. In addition to the determination of the most appropriate acclimation procedure, this approach can be used in the detection of the most resistant bacterial strains to be used in bioremediation studies.

First report of diazotrophic Brevundimonas spp. as growth enhancer and root colonizer of potato.

Rhizobacteria contain various plant-beneficial traits and their inoculation can sustainably increase crop yield and productivity. The present study describes the growth-promoting potential of Brevundimonas spp. isolated from rhizospheric soil of potato from Sahiwal, Pakistan. Four different putative strains TN37, TN39, TN40, and TN44 were isolated by enrichment on nitrogen-free malate medium and identified as Brevundimonas spp. based on their morphology, 16S rRNA gene sequence, and phylogenetic analyses. All strains contained nifH gene except TN39 and exhibited nitrogen fixation potential through acetylene reduction assay (ARA) except TN40. Among all, the Brevundimonas sp. TN37 showed maximum ARA and phosphate solubilization potential but none of them exhibited the ability to produce indole acetic acid. Root colonization studies using transmission electron microscopy and confocal laser scanning microscopy showed that Brevundimonas sp. TN37 was resident over the root surface of potato; forming sheets in the grooves in the rhizoplane. TN37, being the best among all was further evaluated in pot experiment using potato cultivar Kuroda in sterilized sand. Results showed that Brevundimonas sp. TN37 increased growth parameters and nitrogen uptake as compared to non-inoculated controls. Based on the results obtained in this study, it can be suggested that Brevundimonas spp. (especially TN37) possess the potential to improve potato growth and stimulate nitrogen uptake. This study is the first report of Brevundimonas spp. as an effective PGPR in potato.

Brevundimonas diminuta bacteremia in a man with myelodysplastic syndromes.

Brevundimonas diminuta are ubiquitous in the environment, but are infrequently isolated from clinical samples. Here we report a case of B. diminuta bacteremia in a man with myelodysplastic syndromes (MDS) at a teaching hospital in China and review the previously reported cases. The organism was confirmed by culture and 16s rRNA sequence analysis with highly sensitivity to broad-spectrum antibiotics. Our report and other cases demonstrated that the optimal therapeutic duration for B. diminuta infections in various situations remains to be established.

Contamination of Phenylobacterium in several human and murine cell cultures.

OBJECTIVE: To identify and characterize an unknown microorganism causing contamination in several mammalian cell cultures. METHODS: This bacterium was identified by 16S rRNA sequencing and studied by DAPI and DiOC6 (3) staining, Gram staining, acid-fast staining, and electron microscopy. The isolated bacterium was also used to infect host cells to observe antibiotic effectiveness and its relationship with host cells. RESULTS: The 16S rRNA sequence analysis shows that this rod-shaped microorganism belongs to the family Caulobacteraceae, class Alphaproteobacteria, and was most closely related to Phenylobacterium zucineum HLK1T strain. The bacterium collected in the "swimming" stage was Gram staining negative, but Gram staining positive in the "sessile" stage. Under the electron microscope both flagellated and non-flagellated types were found. So far, no antibiotics were effective to inhibit this microorganism. The contamination with this bacterium frequently led to failed resuscitation of thawed cells. We found that the cells resuscitated with the used culture supernatants were increased in number by 3-4 folds as compared to those resuscitated with freshly prepared media. CONCLUSION: Phenylobacterium may have a dimorphic life cycle including a swimming stage and a sessile stalked stage.

Identification of anthraquinone-degrading bacteria in soil contaminated with polycyclic aromatic hydrocarbons.

Quinones and other oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are toxic and/or genotoxic compounds observed to be cocontaminants at PAH-contaminated sites, but their formation and fate in contaminated environmental systems have not been well studied. Anthracene-9,10-dione (anthraquinone) has been found in most PAH-contaminated soils and sediments that have been analyzed for oxy-PAHs. However, little is known about the biodegradation of oxy-PAHs, and no bacterial isolates have been described that are capable of growing on or degrading anthraquinone. PAH-degrading Mycobacterium spp. are the only organisms that have been investigated to date for metabolism of a PAH quinone, 4,5-pyrenequinone. We utilized DNA-based stable-isotope probing (SIP) with [U-(13)C]anthraquinone to identify bacteria associated with anthraquinone degradation in PAH-contaminated soil from a former manufactured-gas plant site both before and after treatment in a laboratory-scale bioreactor. SIP with [U-(13)C]anthracene was also performed to assess whether bacteria capable of growing on anthracene are the same as those identified to grow on anthraquinone. Organisms closely related to Sphingomonas were the most predominant among the organisms associated with anthraquinone degradation in bioreactor-treated soil, while organisms in the genus Phenylobacterium comprised the majority of anthraquinone degraders in the untreated soil. Bacteria associated with anthracene degradation differed from those responsible for anthraquinone degradation. These results suggest that Sphingomonas and Phenylobacterium species are associated with anthraquinone degradation and that anthracene-degrading organisms may not possess mechanisms to grow on anthraquinone.

Evidence for grow-through penetration of 0.2-µm-pore-size filters by Serratia marcescens and Brevundimonas diminuta.

We find that both Brevundimonas diminuta and Serratia marcescens can grow through sterilizing grade filter membranes of different membrane polymer compositions. Although this passage does not occur on a consistent basis, generation of "grow-through positive" results indicate that grow-through can occur stochastically at basal levels. This observation argues that the following risk mitigation strategies during pharmaceutical aseptic processing are warranted: minimization of processing times, and monitoring, minimizing and characterizing pre-filter bioburden.

Optimization of L-DOPA production by Brevundimonas sp. SGJ using response surface methodology.

L-DOPA (3,4-dihydroxyphenyl-L-alanine) is an extensively used drug for the treatment of Parkinson's disease. In the present study, optimization of nutritional parameters influencing L-DOPA production was attempted using the response surface methodology (RSM) from Brevundimonas sp. SGJ. A Plackett-Burman design was used for screening of critical components, while further optimization was carried out using the Box-Behnken design. The optimized levels of factors predicted by the model were pH 5.02, 1.549 g l(-1) tryptone, 4.207 g l(-1) L-tyrosine and 0.0369 g l(-1) CuSO(4) , which resulted in highest L-DOPA yield of 3.359 g l(-1). The optimization of medium using RSM resulted in a 8.355-fold increase in the yield of L-DOPA. The anova showed a significant R(2) value (0.9667), model F-value (29.068) and probability (0.001), with insignificant lack of fit. The highest tyrosinase activity observed was 2471 U mg(-1) at the 18th hour of the incubation period with dry cell weight of 0.711 g l(-1). L-DOPA production was confirmed by HPTLC, HPLC and GC-MS analysis. Thus, Brevundimonas sp. SGJ has the potential to be a new source for the production of L-DOPA.

Filters reduce the risk of bacterial transmission from contaminated heated humidifiers used with CPAP for obstructive sleep apnea.

RATIONALE: The treatment of choice for obstructive sleep apnea (OSA) is nasal continuous positive airway pressure (nCPAP) during sleep, but dryness of the upper airway compromises compliance. Heated humidifiers may mitigate such noncompliance; however, recent observations suggest that their use, particularly if not cleaned, increases the risk of respiratory infections. Humidifier water may be contaminated, but the long-held view that passive humidifiers cannot aerosolize water may obscure the perception of risk of infection. OBJECTIVES: This study challenges the long-held view that "passover" humidifiers do not aerosolize water. With such evidence, this study characterizes the performance of filters to reduce the potential risk of contamination. METHODS: Heated humidifier water contaminated with bacteria was studied under conditions simulating week-long use of nCPAP for OSA. RESULTS: Bacteria were recovered in 9 of 11 tests from the breathing tubes of CPAP devices fitted with heated humidifiers with water contaminated with Brevundimonas diminuta or Serratia marcescens. Recoverable bacteria ranged from tens to thousands of colony forming units when tested at air flow rates of 60 liters per minute for 90 minutes. Neither organism was recovered from the circuit tubing when a hydrophobic breathing-circuit filter was positioned between the humidifier and face-mask tubing with a commercially available nCPAP machine tested under simulated-use conditions. CONCLUSION: Data suggest that patients with OSA being treated with nCPAP fitted with humidifiers may be aerosolizing bacteria, putting them at risk for developing respiratory infections and that the use of a hydrophobic filter may attenuate the passage of microbes from contaminated humidifier water.

Ecological significance of microdiversity: identical 16S rRNA gene sequences can be found in bacteria with highly divergent genomes and ecophysiologies.

A combination of cultivation-based methods with a molecular biological approach was used to investigate whether planktonic bacteria with identical 16S rRNA gene sequences can represent distinct eco- and genotypes. A set of 11 strains of Brevundimonas alba were isolated from a bacterial freshwater community by conventional plating or by using a liquid most-probable-number (MPN) dilution series. These strains had identical 16S rRNA gene sequences and represented the dominant phylotype in the plateable fraction, as well as in the highest positive dilutions of the MPN series. However, internally transcribed spacer and enterobacterial repetitive intergenic consensus PCR fingerprinting analyses, as well as DNA-DNA hybridization analyses, revealed great genetic diversity among the 11 strains. Each strain utilized a specific combination of 59 carbon substrates, and the niche overlap indices were low, suggesting that each strain occupied a different ecological niche. In dialysis cultures incubated in situ, each strain had a different growth rate and cell yield. We thus demonstrated that the B. alba strains represent distinct populations with genetically determined adaptations and probably occupy different ecological niches. Our results have implications for assessment of the diversity and biogeography of bacteria and increase the perception of natural diversity beyond the level of 16S rRNA gene sequences.