The biosynthesis of medium-chain-length poly-3-hydroxyalkanoates by Pseudomonas putida Bet001 cultivated on mixed carbon sources was investigated. The mixed carbon sources consisted of heptanoic acid (HA) and oleic acid (OA). A relatively low PHA content at 1.2% (w/w) and 11.4% (w/w) was obtained when HA or OA was used as the sole carbon source. When these fatty acids were supplied as a mixture, PHA content increased threefold. Interestingly, the mixture-derived PHA composed of both odd and even monomer units, namely. 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate and no unsaturated monomer was detected. It is hypothesized that the even-numbered monomers were derived primarily from OA, whereas the odd-numbered monomer was derived from HA. This also points out to an efficient and yet distinct fatty acids metabolism that fed the PHA biosynthesis machinery of this particular microorganism. PHA obtained was elastomeric because melting temperature (Tm ) and crystallinity were absent. It showed good thermal stability with degradation temperature (Td ) ranging from 275.96 to 283.05 °C.
The bioremediation of polluted groundwater, wastewater aeration pond and biopond sites was investigated using bacteria isolated from these sites located at the oil refinery Terengganu Malaysia. Out of 62 isolates, only 16 isolates from groundwater (8) and wastewater aeration pond (3) and biopond (5) were chosen based on growth medium containing 1% (v/v) Tapis crude oil. Only four isolates; Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata showed percentage biodegradation of crude oil more than 50% after 5 days using Mineral Salts Medium (MSM). The effect of physical parameters (temperature, pH and agitation) on growth by all four strains showed a maximum growth in MSM medium with 1% Tapis crude oil at 37 degrees C with pH 7 and agitation of 130 rpm.
Epidemiology of melioidosis is poorly understood because its occurrence is influenced by complex interaction of environmental, climatic, physicochemical and host factors. We investigated the potential risk factors for the exposure to Burkholderia pseudomallei in small ruminants' farms in Peninsular Malaysia.
Burkholderia pseudomallei causes melioidosis, a life-threatening infection in both humans and animals. Water is an important reservoir of the bacteria and may serve as a source of environmental contamination leading to infection. B. pseudomallei has an unusual ability to survive in water for a long period. This paper investigates physicochemical properties of water associated with the presence of B. pseudomallei in water supply in small ruminant farms in Peninsular Malaysia. Physicochemical properties of water samples taken from small ruminant farms that included temperature, pH, dissolved oxygen (DO2), optical density (OD), and chemical oxygen demand (COD) were measured after which the samples were cultured for B. pseudomallei. Multivariable logistic regression model revealed that slightly acidic water pH and higher COD level were significantly associated with the likelihood of the B. pseudomallei presence in the water.
Matched MeSH terms: Fresh Water/microbiology; Water Microbiology/standards*
A total of 182 isolates of Plesiomonas shigelloides were identified from 40 healthy red hybrid tilapia, Oreochromis niloticus cultured at two important rivers in Terengganu, Malaysia namely Como River and Terengganu River from east coast Malaysia. P. shigelloides count in Digestive Tract Content (DTC) and Muscle (MUS) of red hybrid tilapia cultured at Terengganu River was 1000-fold higher than Como River. Antibiotic susceptibility test was also performed on Plesiomonas shigelloides isolates. The incidence of antibiotic resistance was higher in Plesiomonas shigelloides isolated from red hybrid tilapia cultured at Terengganu River compared to Como river. Thus, the findings of the study indicate that P. shigelloides from tilapia muscle and an intestine could be an alarming for serious public health risk to consumers.
This study focuses on the evaluation of the performance of Chlorella sp. in removing nutrient in aquaculture wastewater and its correlation with the kinetic growth of Chlorella sp. The treatment was applied with various Chlorella sp. inoculation dosage ranging from 0% to 60% (v/v) of wastewater. The optimum inoculation dosage was recorded at 30% (v/v) with effluent concentration of ammonia and orthophosphate recording at 0.012mgL(-1) and 0.647mgL(-1), respectively on Day 11. The optimum dosage for bio-flocculation process was obtained at 30mgL(-1) of Aspergillus niger with a harvesting efficiency of 97%. This type of development of phytoremediation with continuous bio-harvesting could promote the use of sustainable green technology for effective wastewater treatment.
Aquitalea sp. USM4 (JCM 19919) was isolated from a freshwater sample at Lata Iskandar Waterfall in Perak, Malaysia. It is a rod-shaped, gram-negative bacterium with high sequence identity (99%) to Aquitalea magnusonii based on 16S rRNA gene analysis. Aquitalea sp. USM4 also possessed a PHA synthase gene (phaC), which had amino acid sequence identity of 77-78% to the PHA synthase of Chromobacterium violaceum ATCC12472 and Pseudogulbenkiania sp. NH8B. PHA biosynthesis results showed that wild-type Aquitalea sp. USM4 was able to accumulate up to 1.5 g/L of poly(3-hydroxybutyrate), [P(3HB)]. The heterologous expression of the PHA synthase gene of Aquitalea sp. USM4 (phaCAq) in Cupriavidus necator PHB(-)4 had resulted in PHA accumulation up to 3.2 g/L of P(3HB). It was further confirmed by (1)H nuclear magnetic resonance (NMR) analysis that Aquitalea sp. USM4 and C. necator PHB(-)4 transformant were able to produce PHA containing 3-hydroxyvalerate (3HV), 4-hydroxybutyrate (4HB) and 3-hydroxy-4-methylvalerate (3H4MV) monomers from suitable precursor substrates. Interestingly, relatively high PHA synthase activity of 863 U/g and 1402 U/g were determined in wild-type Aquitalea sp. USM4 and C. necator PHB(-)4 transformant respectively. This is the first report on the member of genus Aquitalea as a new PHA producer as well as in vitro and in vivo characterization of a novel PHA synthase from Aquitalea sp. USM4.
Three building complexes in Kuala Lumpur were surveyed for the presence of legionellae in cooling towers. The organisms were grown from 12 out of 46 samples of water collected from 30 towers. L. pneumophila serogroups 1 and 7 were the commonest serogroups isolated. None belonged to the Pontiac subgroup of L. pneumophila serogroup 1.
Microalgal bacterial flocs can be a promising approach for microalgae harvesting and wastewater treatment. The present study provides an insight on the bioflocs formation to enhance harvesting of Chlorella vulgaris and the removal of nutrients from seafood wastewater effluent. The results showed that the untreated seafood wastewater was the optimal culture medium for the cultivation and bioflocculation of C. vulgaris, with the flocculating activity of 92.0 ± 6.0%, total suspended solids removal of 93.0 ± 5.5%, and nutrient removal of 88.0 ± 2.2%. The bioflocs collected under this optimal condition contained dry matter of 107.2 ± 5.6 g·L-1 and chlorophyll content of 25.5 ± 0.2 mg·L-1. The results were promising when compared to those obtained from the auto-flocculation process that induced by the addition of calcium chloride and pH adjustment. Additionally, bacteria present in the wastewater aided to promote the formation of bioflocculation process.
Nowadays, the pretreatment of wastewater prior to discharge is very important in various industries as the wastewater without any treatment contains high organic pollution loads that would pollute the receiving waterbody and potentially cause eutrophication and oxygen depletion to aquatic life. The reuse of seafood wastewater discharge in microalgae cultivation offers beneficial purposes such as reduced processing cost for wastewater treatment, replenishing ground water basin as well as financial savings for microalgae cultivation. In this paper, the cultivation of Chlorella vulgaris with an initial concentration of 0.01 ± 0.001 g⋅L-1 using seafood sewage discharge under sunlight and fluorescent illumination was investigated in laboratory-scale without adjusting mineral nutrients and pH. The ability of nutrient removal under different lighting conditions, the metabolism of C. vulgaris and new medium as well as the occurrence of auto-flocculation of microalgae biomass were evaluated for 14 days. The results showed that different illumination sources did not influence the microalgae growth, chemical oxygen demand (COD) and biochemical oxygen demand (BOD) significantly. However, the total nitrogen (total-N) and total phosphorus (total-P) contents of microalgae were sensitive to the illumination mode. The amount of COD, BOD, total-N and total-P were decreased by 88%, 81%, 95%, and 83% under sunlight mode and 81%, 74%, 79%, and 72% under fluorescent illumination, respectively. Furthermore, microalgae were auto-flocculated at the final days of cultivation with maximum biomass concentration of 0.49 ± 0.01 g⋅L-1, and the pH value had increased to pH 9.8 ± 0.1 under sunlight illumination.
The inactivation of antibiotic resistant Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) seeded in greywater by bimetallic bio-nanoparticles was optimized by using response surface methodology (RSM). The bimetallic nanoparticles (Cu/Zn NPs) were synthesized in secondary metabolite of a novel fungal strain identified as Aspergillus iizukae EAN605 grown in pumpkin medium. Cu/Zn NPs were very effective for inhibiting growth of E. coli and S. aureus. The maximum inactivation was optimized with 0.028 mg mL-1 of Cu/Zn NPs, at pH 6 and after 60 min, at which the reduction of E. coli and S. aureus was 5.6 vs. 5.3 and 5.2 vs. 5.4 log reduction for actual and predicted values, respectively. The inactivation mechanism was described based on the analysis of untreated and treated bacterial cells by Field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) revealed a damage in the cell wall structure due to the effect of Cu/Zn NPs. Moreover, the Raman Spectroscopy showed that the Cu/Zn NPs led to degradation of carbohydrates and amino structures on the bacteria cell wall. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed that the destruction take place in the C-C bond of the functional groups available in the bacterial cell wall. The techno economic analysis revealed that the biosynthesis Cu/Zn NPs is economically feasible. These findings demonstrated that Cu/Zn NPs can effectively inhibit pathogenic bacteria in the greywater.
The detection of Vibrio cholerae 01 from the aquatic environment of Daro and Bintulu in Sarawak was carried out following an outbreak of cholera. Conventional culture methods and detection of ctx gene by polymerase chain reaction technique were carried out on 80 water samples. Only one sample was positive by culture methods while 8 were positive by PCR. DNA finger printing by pulsed-field gel electrophoresis showed that the clinical isolates in Daro and Bintulu were genetically identical while the environmental isolate was closely related. Recovery of Vibrio cholerae by culture method is poor and newer methods of detection should be developed.
This study aimed to compare population dynamics, antibiotic resistance and biofilm formation of Aeromonas and Vibrio species from seawater and sediment collected from Northern Malaysia. Isolates with different colony morphology were characterized using both biochemical and molecular methods before testing for antibiotic resistance and biofilm formation. Results obtained from this study showed that in Kedah, the population of Aeromonas isolated from sediment was highest in Pantai Merdeka (8.22 log CFU/ml), Pulau Bunting recorded the highest population of Aeromonas from sediment (8.43 log CFU/g). It was observed that Vibrio species isolated from seawater and sediment were highest in Kuala Sanglang (9.21 log CFU/ml). In Kuala Perlis, the population of Aeromonas isolated from seawater was highest in Jeti (7.94 log CFU/ml). Highest population of Aeromonas from sediment was recorded in Kampong Tanah Baru (7.99 log CFU/g). It was observed that Vibrio species isolated from seawater was highest in Padang Benta (8.42 log CFU/g) while Jeti Kuala Perlis had highest population of Vibrio isolated from sediment. It was observed that location does not influence population of Aeromonas. The results of the independent t - test revealed that there was no significant relationship between location and population of Vibrio (df = 10, t = 1.144, p > 0.05). The occurrence of biofilm formation and prevalence of antibiotic resistant Aeromonas and Vibrio species in seawater and sediment pose danger to human and aquatic animals' health.
Wastewater treatment systems employing simultaneous adsorption and biodegradation processes have proven to be effective in treating toxic pollutants present in industrial wastewater. The objective of this study is to evaluate the effect of Cu(II) and the efficacy of the powdered activated carbon (PAC) and activated rice husk (ARH) in reducing the toxic effect of Cu(II) on the activated sludge microorganisms. The ARH was prepared by treatment with concentrated nitric acid for 15 h at 60-65 degrees C. The sequencing batch reactor (SBR) systems were operated with FILL, REACT, SETTLE, DRAW and IDLE modes in the ratio of 0.5:3.5:1:0.75:0.25 for a cycle time of 6 h. The Cu(II) and COD removal efficiency were 90 and 85%, respectively, in the SBR system containing 10 mg/l Cu(II) with the addition of 143 mg/l PAC or 1.0 g PAC per cycle. In the case of 715 mg/l ARH or 5.0 g ARH per cycle addition, the Cu(II) and COD removal efficiency were 85 and 92%, respectively. ARH can be used as an alternate adsorbent to PAC in the simultaneous adsorption and biodegradation wastewater treatment process for the removal of Cu(II). The specific oxygen uptake rate (SOUR) and kinetic studies show that the addition of PAC and ARH reduce the toxic effect of Cu(II) on the activated sludge microorganisms.
The present study demonstrated that aerobic granular sludge is capable of treating livestock wastewater from a cattle farm in a sequencing batch reactor (SBR) without the presence of support material. A lab scale SBR was operated for 80 d using 4 h cycle time with an organic loading rate (OLR) of 9 kg COD m(-3) d(-1). Results showed that the aerobic granules were growing from 0.1 to 4.1 mm towards the end of the experimental period. The sludge volume index (SVI) was 42 ml g(-1) while the biomass concentration in the reactor grew up to 10.3 g L(-1) represent excellent biomass separation and good settling ability of the granules. During this period, maximum COD, TN and TP removal efficiencies (74%, 73% and 70%, respectively) were observed in the SBR system, confirming high microbial activity in the SBR system.
Pectobacterium carotovorum M022T has been isolated from a waterfall source in Selangor district (Malaysia). Using genomic and phenotypic tests, we re-examined the taxonomical position of this strain. Based on 14 concatenated housekeeping genes (fusA, rpoD, rpoS, acnA, purA, gyrB, recA, mdh, mtlD, groEL, secY, glyA, gapA and rplB), multi-locus sequence analysis revealed that strain M022T falls into a novel clade separated from the other Pectobacterium species. The in silico DNA-DNA hybridization and average nucleotide identity values were lower than the 70 and 95 % threshold values, respectively. In addition, by combining genomic and phenotypic tests, strain M022T may be distinguished from the other Pectobacterium isolates by its incapacity to grow on d(+)-xylose, l-rhamnose, cellobiose and lactose. Strain M022T (=CFBP 8629T=LMG 30744T) is proposed as the type strain of the Pectobacteriumfontis sp. nov.
Strains 2B12T, FVG1-MFV-O17 and FVG10-MFV-A16 were isolated from fresh water samples collected in Asia and Europe. The nucleotide sequences of the gapA barcodes revealed that all three strains belonged to the same cluster within the genus Dickeya. Using 13 housekeeping genes (fusA, rpoD, rpoS, glyA, purA, groEL, gapA, rplB, leuS, recA, gyrB, infB and secY), multilocus sequence analysis confirmed the existence of a new clade. When the genome sequences of these three isolates and other Dickeya species were compared, the in silico DNA-DNA hybridization and average nucleotide identity values were found to be no more than 45.50 and 91.22 %, respectively. The closest relative species was Dickeya fangzhongdai. Genome comparisons also highlighted genetic traits differentiating the new strains from D. fangzhongdai strains DSM 101947T (=CFBP 8607T) and B16. Phenotypical tests were performed to distinguish the three strains from D. fangzhongdai and other Dickeya species. The name Dickeya undicola sp. nov. is proposed with strain 2B12T (=CFBP 8650T=LMG 30903T) as the type strain.
This review briefly summarizes the geographical distribution and clinical impact of melioidosis, especially in the tropics. Burkholderia pseudomallei (a gram-negative bacterium) is the major causative agent for melioidosis, which is prevalent in Singapore, Malaysia, Thailand, Vietnam, and Northern Australia. Melioidosis patients are increasingly being recognized in other parts of the world. The bacteria are intrinsically resistant to many antimicrobial agents, but prolonged treatment, especially with combinations of antibiotics, may be effective. Despite therapy, the overall case fatality rate of septicemia in melioidosis remains significantly high. Intracellular survival of the bacteria within macrophages may progress to chronic infections, and about 10% of patients suffer relapses. In the coming decades, melioidosis will increasingly afflict travelers throughout many global regions. Clinicians managing travelers returning from the subtropics or tropics with severe pneumonia or septicemia should consider acute melioidosis as a differential diagnosis. Patients with open skin wounds, diabetes, or chronic renal disease are at higher risk for melioidosis and should avoid direct contact with soil and standing water in endemic regions. Furthermore, there are fears that B. pseudomallei may be used as a biological weapon. Technological advancements in molecular diagnostics and antibiotic therapy are improving the disease outcomes in endemic areas throughout Asia. Research and development efforts on vaccine candidates against melioidosis are ongoing.
A baseline study was carried out to assess the metal concentrations and microbial contamination at selected Lake waters in and around Miri City, East Malaysia. Sixteen surface water samples were collected at specific Lakes in the environs of major settlement areas and recreational centers in Miri City. The Physico-chemical parameters [pH, Electrical Conductivity (EC) and Dissolved Oxygen (DO)], metals (Fe, Mn, Cu, Cd, Ni and Zn) and Escherichia coli (E. coli) were analysed. The concentrations of Fe, Mn and Ni have been found to be above the permissible limits of drinking water quality standards. The metals data have also been used for the calculation of heavy metal pollution index. Higher values of E. coli indicate microbial contamination in the Lake waters.