A Novel Jumbo Phage PhiMa05 Inhibits Harmful Microcystis sp.

Microcystis poses a concern because of its potential contribution to eutrophication and production of microcystins (MCs). Phage treatment has been proposed as a novel biocontrol method for Microcystis. Here, we isolated a lytic cyanophage named PhiMa05 with high efficiency against MCs-producing Microcystis strains. Its burst size was large, with approximately 127 phage particles/infected cell, a short latent period (1 day), and high stability to broad salinity, pH and temperature ranges. The PhiMa05 structure was composed of an icosahedral capsid (100 nm) and tail (120 nm), suggesting that the PhiMa05 belongs to the Myoviridae family. PhiMa05 inhibited both planktonic and aggregated forms of Microcystis in a concentration-dependent manner. The lysis of Microcystis resulted in a significant reduction of total MCs compared to the uninfected cells. A genome analysis revealed that PhiMa05 is a double-stranded DNA virus with a 273,876 bp genome, considered a jumbo phage. Out of 254 predicted open reading frames (ORFs), only 54 ORFs were assigned as putative functional proteins. These putative proteins are associated with DNA metabolisms, structural proteins, host lysis and auxiliary metabolic genes (AMGs), while no lysogenic, toxin and antibiotic resistance genes were observed in the genome. The AMGs harbored in the phage genome are known to be involved in energy metabolism [photosynthesis and tricarboxylic acid cycle (TCA)] and nucleotide biosynthesis genes. Their functions suggested boosting and redirecting host metabolism during viral infection. Comparative genome analysis with other phages in the database indicated that PhiMa05 is unique. Our study highlights the characteristics and genome analysis of a novel jumbo phage, PhiMa05. PhiMa05 is a potential phage for controlling Microcystis bloom and minimizing MC occurrence

Microcystis Sp. Co-Producing Microcystin and Saxitoxin from Songkhla Lake Basin, Thailand

The Songkhla Lake Basin (SLB) located in Southern Thailand, has been increasingly polluted by urban and industrial wastewater, while the lake water has been intensively used. Here, we aimed to investigate cyanobacteria and cyanotoxins in the SLB. Ten cyanobacteria isolates were identified as Microcystis genus based on16S rDNA analysis. All isolates harbored microcystin genes, while five of them carried saxitoxin genes. On day 15 of culturing, the specific growth rate and Chl-a content were 0.2–0.3 per day and 4 µg/mL. The total extracellular polymeric substances (EPS) content was 0.37–0.49 µg/mL. The concentration of soluble EPS (sEPS) was 2 times higher than that of bound EPS (bEPS). The protein proportion in both sEPS and bEPS was higher than the carbohydrate proportion. The average of intracellular microcystins (IMCs) was 0.47 pg/cell on day 15 of culturing, while extracellular microcystins (EMCs) were undetectable. The IMCs were dramatically produced at the exponential phase, followed by EMCs release at the late exponential phase. On day 30, the total microcystins (MCs) production reached 2.67 pg/cell. Based on liquid chromatograph-quadrupole time-of-flight mass spectrometry, three new MCs variants were proposed. This study is the first report of both decarbamoylsaxitoxin (dcSTX) and new MCs congeners synthesized by Microcystis

Application of terpene-induced cell for enhancing biodegradation of TCE contaminated soil

Trichloroethylene (TCE), a chlorinated solvent, is a major water pollutant originating from spillage and inappropriate disposal of dry cleaning agents, degreasing solvents, and paint strippers. Due to its widespread contamination and potential health threat, remediation technology to clean-up TCE is necessary. Aerobic biodegradation of TCE is reported to occur via cometabolism, by which TCE degrading bacteria utilize other compounds such as toluene, phenol, and methane as growth substrate and enzyme inducer. Although toluene is reported to be the most effective inducer, it is regulated as a hazardous material and should not be applied to the environment. The objectives of this study were to identify an alternative enzyme inducer as well as to apply the induced bacteria for degradation of TCE in contaminated soil. We investigated the effect of terpenes, the main components in volatile essential oils of plants, on induction of TCE degradation in Rhodococcus gordoniae P3, a local Gram (+) bacterium. Selected terpenes including cumene, limonene, carvone and pinene at various concentrations were used in the study. Results from liquid culture showed that 25 mg l-1 cumeneinduced R. gordoniae P3 cells resulted in 75% degradation of 10 ppm TCE within 24 hrs. Soil microcosms were later employed to investigate the ability of cumene to enhance TCE biodegradation in the environment. There were two bioremediation treatments studied, including bioaugmentation, the inoculation of cumeneinduced R. gordoniae P3, and biostimulation, the addition of cumene to induce soil indigenous microorganisms to degrade TCE. Bioaugmentation and biostimulation were shown to accelerate TCE reduction significantly more than control treatment at the beginning of study. The results suggest that cumene-induced R. gordoniae P3 and cumene can achieve rapid TCE biodegradation

Cometabolic Degradation of Trichloroethene by Rhodococcus sp. Strain L4 Immobilized on Plant Materials Rich in Essential Oils▿ †

The cometabolic degradation of trichloroethene (TCE) by Rhodococcus sp. L4 was limited by the loss of enzyme activity during TCE transformation. This problem was overcome by repeated addition of inducing substrates, such as cumene, limonene, or cumin aldehyde, to the cells. Alternatively, Rhodococcus sp. L4 was immobilized on plant materials which contain those inducers in their essential oils. Cumin seeds were the most suitable immobilizing material, and the immobilized cells tolerated up to 68 μM TCE and degraded TCE continuously. The activity of immobilized cells, which had been inactivated partially during TCE degradation, could be reactivated by incubation in mineral salts medium without TCE. These findings demonstrate that immobilization of Rhodococcus sp. L4 on plant materials rich in essential oils is a promising method for efficient cometabolic degradation of TCE

Application of terpene-induced cell for enhancing biodegradation of TCE contaminated soil Application of terpene-induced cell for enhancing biodegradation of TCE contaminated soil

Trichloroethylene (TCE), a chlorinated solvent, is a major water pollutant originating from spillage and inappropriate disposal of dry cleaning agents, degreasing solvents, and paint strippers. Due to its widespread contamination and potential health threat, remediation technology to clean-up TCE is necessary. Aerobic biodegradation of TCE is reported to occur via cometabolism, by which TCE degrading bacteria utilize other compounds such as toluene, phenol, and methane as growth substrate and enzyme inducer. Although toluene is reported to be the most effective inducer, it is regulated as a hazardous material and should not be applied to the environment. The objectives of this study were to identify an alternative enzyme inducer as well as to apply the induced bacteria for degradation of TCE in contaminated soil. We investigated the effect of terpenes, the main components in volatile essential oils of plants, on induction of TCE degradation in Rhodococcus gordoniae P3, a local Gram (+) bacterium. Selected terpenes including cumene, limonene, carvone and pinene at various concentrations were used in the study. Results from liquid culture showed that 25 mg l -1 cumeneinduced R. gordoniae P3 cells resulted in 75% degradation of 10 ppm TCE within 24 hrs. Soil microcosms were later employed to investigate the ability of cumene to enhance TCE biodegradation in the environment

Assessing human exposure to PM10-bound polycyclic aromatichydrocarbons during fireworks displays

The “Loy Krathong” festival is a major annual Thai event that includes firework displays. It takes place on the evening of the full moon in the 12th month of the traditional Thai lunar calendar. Since fireworks are widely considered a major source of PAHs, it is considered reasonable to expect a significant increase in PAH levels during this event. The overall PAH profile at the six air quality observatories operated by the Pollution Control Department (PCD), Ministry of Natural Resources and Environment (MNRE), showed that the Kingdom of Thailand's atmosphere was dominated by 5–6-ring PAHs during the firework display period. A significant increase in ΣPAHs (153%) was observed during firework displays. A statistical analysis coupled with the application of diagnostic binary PAH ratios was conducted to determine whether the detected increase in PAH congeners during the festival period was due to firework combustion or whether it was a coincidental effect caused by vehicular exhausts, long-range atmospheric transportation, photolysis and chemical degradation. The average incremental lifetime cancer risk (ILCR) values of adults and children living in Bangkok as estimated by three different TEQs for ingestion, dermal contact, and inhalation exposure pathways were greatly lesser than the US EPA baseline, further highlighting that the cancer risk of bonfire night falls into the ‘‘acceptable level’’ range

Impacts of PM2.5 sources on variations in particulate chemical compounds in ambient air of Bangkok, Thailand

In this study, PM2.5-bound carbonaceous compounds, including organic carbon (OC), elemental carbon (EC), water-soluble ionic species (WSIS), and polycyclic aromatic hydrocarbons (PAHs) in the ambient air of Bangkok were analysed. The mean PM2.5 concentration was 77.0 +/- 21.2 mu g m(-3), while the average concentrations of OC, and EC were 8.03 +/- 4.02, and 2.62 +/- 1.49 mu g m(-3), respectively. The relatively high OC/EC ratio (3.52 +/- 1.41) coupled with a strong positive correlation between K+ and carbonaceous compounds (K+ vs. OC (r = 0.86), K+ vs. EC (r = 0.87), K+ vs. Char-EC (r = 0.82)) suggest that biomass burning are one of the major contributors to PM2.5 in the sampling area. A comparatively high abundance of both B[g,h,i]P and Ind guides that vehicular exhausts, industrial combustion, and burning of waste might reflect the sources of these PAHs in Bangkok's atmosphere. Interestingly, hierarchical cluster analysis (HCA) indicated that the main source of PM2.5 was a mixture of various combustion activities (e.g. biomass burning, vehicular exhaust, fossil fuel, coal, and industrial emissions). Principal Component Analysis (PCA) successfully classified five principal sources of PM2.5, including vehicular exhaust, biomass burning, sea salt aerosol, power plant, and industrial emissions, which accounted for 43.7%, 24.0%, 10.5%, 6.48%, and 4.46%, respectively. These results indicated that the effects of vehicular exhausts and biomass burning played an important role in governing the PM2.5 level in ambient air of Bangkok. The findings of this study aid policymakers in launching effective air quality control strategies based on the source apportionment analysis

Long-range Transboundary Atmospheric Transport of Polycyclic Aromatic Hydrocarbons, Carbonaceous Compositions, and Water-soluble Ionic Species in Southern Thailand

This study investigated atmospheric particulate matter (PM) with an aerodynamic diameter of < 2.5 mu m (PM2.5) observed at the Prince of Songkla University (Phuket Campus) in southern Thailand. All samples (n = 75) were collected using MiniVolT portable air samplers from March 2017 to February 2018. Carbonaceous aerosol compositions, i.e., organic carbon (OC) and elemental carbon (EC), water-soluble ionic species (WSIS), and polycyclic aromatic hydrocarbons (PAHs) in the PM2.5 samples were identified and quantified. We found that the average PM2.5 concentration was 42.26 +/- 13.45 mu g m(-3), while the average concentrations of OC and EC were 3.05 +/- 1.70 and 0.63 +/- 0.58 mu g m(-3), respectively. The OC/EC ratio was in the range of 2.69-16.9 (mean: 6.05 +/- 2.70), and the average concentration of 10 selected ions was 6.91 +/- 3.54 mu g m(-3). The average concentration of SO42- was the highest throughout the entire study period (2.33 +/- 1.73 mu g m(-3)); the average contribution of SO42- to the major ionic components was 34%. Surprisingly, the average concentrations of NO3- and NH4+ were relatively low. The mean ratio of [NO3-]/[SO42-] was 0.33 +/- 0.24. Strong positive correlation was found between K+ and both OC and EC (r = 0.90 and r = 0.93, respectively). It is also precious to highlight that biomass burning (BB) is the major source of OC, EC and K+, which multiple studies have confirmed that the role of K+ as a biomass marker. Results showed that BB episodes might play a major role in producing the observed high levels of OC. The relatively high abundance of both B[g,h,i]P and Ind suggests that motor vehicles, petroleum/oil combustion, and industrial waste burning are the primary emission sources of PAHs in the ambient air of Phuket. Interestingly, principal component analysis (PCA) indicated that vehicular exhausts are the main source of carbonaceous aerosol compositions found in the ambient air of Phuket, whereas the contributions of biomass burning, diesel emissions, sea salt aerosols and industrial emissions were also important

Effects of Agricultural Waste Burning on PM2.5-Bound Polycyclic Aromatic Hydrocarbons, Carbonaceous Compositions, and Water-Soluble Ionic Species in the Ambient Air of Chiang-Mai, Thailand

PM2.5 is widely regarded as a major air pollutant due to its adverse health impacts and intimate relationship with the climate system. This study aims to characterize the chemical components (e.g., organic carbon (OC), elemental carbon (EC), water soluble ionic species (WSIS) and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 collected at Doi-Inthanon in Chiang-Mai, Thailand, the highest mountain in Thailand. All samples (n = 50) were collected by MiniVolTM portable air samplers from March 2017 to March 2018. In this study we found the average PM2.5 concentration was 100 +/- 48.6 mu g m(-3). The OC/EC ratio was 6.8 +/- 3.0, and the decreasing order of the WSIS concentrations was SO42->Na+>Ca2+>NH4+>NO3->K+>Cl->NO2->Mg2+> F-. The total concentrations of nineteen PAHs were defined as the sum of Ace, Fl, Phe, Ant, Fluo, Pyr, B[a]A, Chry, B[b]F, B[k]F, B[a]F, B[e]P, B[a]P, Per, Ind, B[g,h,i]P, D[a,h]A, Cor, and D[a,e]P. The concentration of total PAHs was 2.361 +/- 2.154 mu g m(-3). Principal component analysis (PCA) highlights the importance of vehicular exhaust, biomass burning, diesel emissions, sea-salt aerosols and volatilization from fertilizers as the five dominant potential sources that accounted for 51.6%, 16.2%, 10.6%, 5.20% and 3.70% of the total variance, respectively. The rest of the 12.7% variance probably is associated with unidentified local and regional sources such as incinerators, joss paper/incense burning, and domestic cooking. Interestingly, the results from the source estimations from the PCA underlined the importance of vehicular exhaust as the major contributor to the PM2.5 concentrations in the ambient air of Don-Inthanon, Chiang-Mai province. However, it is crucial to emphasize that the impacts of agricultural waste burning, fossil fuel combustion, coal combustion and forest fires on the variations of OC, EC and WSIS contents were not negligible