Dephenolization of palm oil mill effluent by oil palm fiber-immobilized Trametes hirsuta AK04 in temporary immersion bioreactor for the enhancement of biogas production.

The dephenolization of palm oil mill effluent (POME) with oil palm fiber-immobilized Trametes hirsuta AK 04 was conducted in a temporary immersion bioreactor to reduce the inhibitory effects of phenolics in anaerobic digestion. Longer immersion times provided greater removal of phenolics due to a higher release of manganese peroxidase. The most effective dephenolization was observed at 6 h immersed and 2 h non-immersed time (immersion ratio 6/8) with maximum removal of 85% from 1277 mg L-1 of phenolics in 4 days. The immobilized fungus maintained its high activity during multiple repeated batch treatments. The pretreated POME of 2 h showed higher methane yields compared with the untreated POME substrate. The methane yields increased with increasing pretreatment time and dephenolization levels. The results suggested that an increased abundance of methanogens was associated with the detoxification of phenolics. The fungal biomass contained crude protein, amino acids, and essential phenolics, which can be used as animal feed supplements.

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.

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.

Effects of crude oil and aromatic compounds on growth and bioluminescence of Vibrio campbellii FS5.

Fifteen native luminescent bacteria were isolated from the Gulf of Thailand, and their sensitivity for the detection of toxicity of crude oil and its aromatic components was investigated. Of these isolates, Vibrio campbellii strain FS5 was one of the two most highly inhibited bacteria at all crude oil concentrations. This bacterium showed a decrease in luminescence intensity of between 10.7 and 80.2% after a 15-min exposure to 0.0001-10 mg/L of crude oil. The degree of bioluminescence inhibition increased with increasing concentrations of crude oil. The presence of crude oil at all concentrations had negative effects on the log bioluminescence per log number of viable cells after 15- to 105-min exposure. About 10 to 100 times, lower half maximal effective concentration (EC50) values were observed for polycyclic aromatic hydrocarbons (PAHs) than those for benzene, toluene, ethylbenzene, and xylene (BTEX). In the presence of each individual BTEX and PAH, the bioluminescence inhibition increased with increasing exposure time (1-32 h). This indigenous bacterium can be used as a simple and general indicator of oil contamination and its impact on coastal waters as well as for assessing potential toxicity during oil bioremediation.

Non-target screening of dissolved organic matter in raw water, coagulated water, and chlorinated water by Orbitrap mass spectrometry.

This study aimed to classify the possible molecular formulas of precursors for disinfection by-products (DBPs) in raw, coagulated, and chlorinated water samples from the U-Tapao Canal, Songkhla, Thailand. The molecular formulas of DBPs in chlorinated water were investigated. Polyaluminum chloride (PACl) was employed as a coagulant. Orbitrap Fourier transform-mass spectrometry was able to estimate the composition of dissolved organic matter (DOM) with the carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S) elements contained and DBPs at the molecular level. The molecular formulas of the DOM in the raw water primarily consisted of CHO and CHON when extracted by lichrolut EN. The CHO and CHON species were rich in lignin-, tannin-, and condensed aromatic-like substances. The DOM with high-molecular-weight from 300 to 500 Da were preferentially removed by coagulation. The PACl coagulation decreased the abundances of lignin-, tannin-, and condensed aromatic-like substances in the CHO formulas, while lignin- and condensed aromatic-like substances in the CHON formulas remained. The remaining precursors corresponded to CHON molecules in the coagulated water, which may result in the formation of some chlorine (Cl)-containing molecules. Several DBPs among the CHOCl and CHONCl species were produced in the chlorinated water through the addition reaction of chlorine. New chlorinated N-DBPs of 21 formulas were detected.

Biodegradation of phenolic compounds present in palm oil mill effluent as single and mixed substrates by Trametes hirsuta AK04.

The ability of white-rot fungus, Trametes hirsuta AK04, to utilize phenolics as single and mixed substrates was determined in mineral medium and palm oil mill effluent (POME). The strain AK04 was able to rapidly metabolize all ten phenolics as single and mixed substrates at all test concentrations. With single substrates, between 78 and 98% removal was achieved within seven days. The biomass yield increased with increasing concentration from 100 to 500 mg L-1 but slightly decreased when the concentration was increased up to 1,000 mg L-1. When fitted to a Haldane model, the groups of benzoic and cinnamic acid derivatives gave significantly higher maximum specific growth rates than other phenolics. Phenol exhibited the lowest affinity and highest inhibitory effects on fungal metabolism. In mixed substrates, the total concentration ranges of phenolics mixtures between 1,000 and 6,000 mg L-1 did not affect the fungal growth rate and the strain AK04 showed a high degree of resistance to their toxic effects. The addition of glucose and yeast extract enhanced the degradation rates of individual phenolics in the substrate mixtures, demonstrating the advantage of this strain for treating complex media, such as industrial wastewater.

Bioaugmentation coupled with phytoremediation for the removal of phenolic compounds and color from treated palm oil mill effluent.

The potential for coupling bioaugmentation with phytoremediation to simultaneously treat and utilize treated palm oil mill effluent (TPOME) in animal feed production was determined from a reduction in phenolic compounds and color in soil leachates, as well as from an increased yield of pasture grass. Two phenol-degrading bacteria-Methylobacterium sp. NP3 and Acinetobacter sp. PK1-were inoculated into the Brachiaria humidicola rhizosphere before the application of TPOME. A pot study showed that the soil with both grass and inoculated bacteria had the highest dephenolization and decolorization efficiencies, with a maximum capability of removing 70% from 587 mg total phenolic compounds added and 73% from 4438 color units during ten TPOME application cycles. The results corresponded to increases in the number of phenol-degrading bacteria and the grass yield. In a field study, this treatment was able to remove 46% from 21,453 mg total phenolic compounds added, with a maximum color removal efficiency of 52% from 5105 color units, while the uninoculated plots removed about 24-39% and 29-46% of phenolic compounds and color, respectively. The lower treatment performance was probably due to the increased TPOME concentrations. Based on the amounts of phenolic compounds, protein, and crude fiber in the grass biomass, the inoculated TPOME-treated grass had a satisfactory nutritional quality and digestibility for use as animal feed.

Degradation of N-nitrosodimethylamine and its amine precursors by cumene-induced Rhodococcus sp. strain L4.

N-nitrosodimethylamine (NDMA) is a potential carcinogen that is produced as a disinfection by-product of chloramination or chlorination process in water and wastewater treatment systems. The ability of the dioxygenase-expressing bacteria, Rhodococcus sp. strain L4, to degrade NDMA after induction with cumene was examined in the presence and absence of its potential precursors. Dimethylamine (DMA), aniline (AN) and humic acid (HA) were selected as the precursors. The induced bacteria were able to degrade NDMA from initial concentrations ranging between 1 and 10 mg L-1 to an undetectable level (< 0.24 µg L-1) while there was no degradation of NDMA by the corresponding non-induced strain. The specific first-order degradation rate of NDMA ranged from 0.337 to 0.426 µg g-protein-1 h-1. Successful removal of all precursors was achieved by the induced bacteria. The presence of DMA had no negative effect on NDMA degradation. In contrast, a lag period was observed for the degradation of NDMA when AN or HA was present (except for the presence of 0.1 mg L-1 AN). In the presence of all precursors, NDMA degradation was negatively affected by the increased concentration (from 1 to 10 mg L-1) of all precursors.

The presence of aliphatic and aromatic amines in reservoir and canal water as precursors to disinfection by-products.

This research aimed at determining the dimethylamine (DMA), diethylamine (DEA), dibutylamine (DBA), and aromatic aniline (AN) in reservoir and canal water in the U-Tapao River Basin, Songkhla, Thailand. The trihalomethane formation potential (THMFP) and N-nitrosodimethylamine formation potential (NDMA-FP) of the reservoir and canal water were analyzed. Water samples from two reservoirs and raw water from water treatment plants at upstream, midstream, and downstream locations of the canal were collected twice. The analysis of the DMA, DEA, DBA, and AN were conducted using gas chromatography and spectrofluorometry techniques. The DMA, DEA, and DBA levels in the reservoir and canal waters ranged from not detectable (ND) to 10 µg/L and from ND to 21.2 µg/L, respectively. AN was detected from 123 to 129 ng/L and from 112 to 177 ng/L in the reservoir and canal waters, respectively. The DMA, DEA, DBA, and AN exhibited two fluorescent peaks at 230nmEx/345nmEm and 280 nmEx/355nmEm. These two peaks corresponded to the peak positions of tryptophan. Detection limits of DMA, DEA, and DBA for fluorescent analysis were 500 µg/L whereas that of AN and tryptophan were 10 and 0.5 µg/L, respectively. The NDMA-FP measured in all the water samples was lower than the detection limit of 237 ng/L. THMFP ranged from 175 to 248 µg/L and 214 to 429 µg/L was detected in the reservoir and canal waters, respectively. The THMFP/dissolved organic carbon (DOC) of the reservoir and canal waters were comparable within the ranges of 73 to 131 µg THMFP/mg DOC.

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 muM 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.

Trichloroethylene cometabolic degradation by Rhodococcus sp. L4 induced with plant essential oils.

Cometabolic degradation of TCE by toluene-degrading bacteria has the potential for being a cost-effective bioremediation technology. However, the application of toluene may pose environmental problems. In this study, several plant essential oils and their components were examined as alternative inducer for TCE cometabolic degradation in a toluene-degrading bacterium, Rhodococcus sp. L4. Using the initial TCE concentration of 80 microM, lemon and lemongrass oil-grown cells were capable of 20 +/- 6% and 27 +/- 8% TCE degradation, which were lower than that of toluene-grown cells (57 +/- 5%). The ability of TCE degradation increased to 36 +/- 6% when the bacterium was induced with cumin oil. The induction of TCE-degrading enzymes was suggested to be due to the presence of citral, cumin aldehyde, cumene, and limonene in these essential oils. In particular, the efficiency of cumin aldehyde and cumene as inducers for TCE cometabolic degradation was similar to toluene. TCE transformation capacities (T (c)) for these induced cells were between 9.4 and 15.1 microg of TCE mg cells(-1), which were similar to the known toluene, phenol, propane or ammonia degraders. Since these plant essential oils are abundant and considered non-toxic to humans, they may be applied to stimulate TCE degradation in the environment.