Optimization of the differential pulse anodic stripping voltammetry technique for determination of cadmium in Pengkalan Chepa River, Kelantan

Cadmium is one of heavy metal that can cause river water pollution by waste from factories. Common exposure of human or animal towards cadmium will cause toxicity. In determination of cadmium, voltammetric technique was used since it is highly sensitive, low cost and low limit of detection. This technique was used for qualitative and quantitative determination of cadmium in water samples. Samples were collected from five rivers; Sungai Alor B, Sungai Alor Lintah, Sungai Keladi, Sungai Pengkalan Chepa and Sungai Pengkalan Chepa 2 which are tributaries of main river, Pengkalan Chepa River at different depth (surface and bottom). Differential Pulse Anodic Stripping Voltammetry (DPSA V) technique was carried out using three electrodes, hanging mercury drop electrode (HMDE) act as working electrode, Ag/AgCI/KCI saturated act as reference electrode and platinum electrode act as auxiliary electrode. The supporting electrolyte used was acetate buffer (1.38 M, pH 4.6). The optimum voltammetric parameters to determine cadmium in river water were initial potential (Ei) -1 V, final potential (Er) -0.2 V, scan rate (v) 5 mV/s, voltage step 0.005 V, voltage step time 1 s, deposition potential (Eacc) -1 V, deposition time (tacc) 60s and equilibrium time (teq) 1000 s. Using this optimized parameters, peak potential (Ep) for cadmium standard was found at -0.632 V. The linear range of cadmium was observed over the concentration range 0.26 ppm to 1.32 ppm with correlation coefficient (r) 0.993, standard deviation (SD) 0.500, sensitivity 10.227 nA/ppm and limit of detection 147 ppb. The method had been successfully applied for determination of cadmium in real samples. The results showed that cadmium was absent in all the samples

Recent update on the prevalence of Vibrio species among cultured grouper in Peninsular Malaysia

Vibrio infections are common among marine fish and lead to serious problems in the aquaculture sector. This study reports a recent occurrence of Vibrio species (spp.) isolated from cultured groupers in Peninsular Malaysia using the gyrB and pyrH genes. A total of 147 Vibrio strains were successfully isolated from 77 (64%) groupers using culture method and subjected to gyrB and pyrH sequencing for species identification and confirmation. Results showed that 89% of Vibrio strains were identified and clustered to six groups of Vibrio spp., while 11% were not clustered to any Vibrio spp. using the gyrB sequences. Meanwhile, by analysis of the pyrH sequences all the 147 Vibrio strains (100%) were successfully identified and clustered into 11 groups of Vibrio spp., including the gyrB non‐identified strains. The pyrH gene provides a better resolution for identification of Vibrio spp. compared with the gyrB gene. Thus, the pyrH gene was more suitable for a rapid determination of Vibrio spp. distribution in Peninsular Malaysia. Using the pyrH gene, our study found higher prevalence of Vibrio vulnificus (33%), V. alginolyticus (24%) and V. parahaemolyticus (22%), followed by V. rotiferianus (5%), V. harveyi (3%), V. tubiashii (2%), V. campbellii (2%), V. ponticus (1%), V. diabolicus (1%), V. owensii (1%) and others Vibrio sp. (7%). Thus, the results of this study revealed that the occurrence of pathogenic vibrios among grouper fish is still high in Malaysian aquaculture. In addition, the pyrH gene was proved as a suitable marker for rapid identification of Vibrio species compared with the gyrB gene

Natural concurrent infection of Vibrio harveyi and V. alginolyticus in cultured hybrid groupers in Malaysia

In September 2016, a marine fish farm operator in Selangor, Malaysia, reported a disease outbreak affecting juvenile hybrid groupers (Camouflage Grouper Epinephelus polyphekadion × Tiger Grouper E. fuscoguttatus). The average daily mortality was 120 fish, resulting in a cumulative mortality rate of 29% within 10 d. The affected hybrid groupers displayed lethargy, excessive mucus production, rotten fins, congestion of livers and kidneys, and enlargement of spleens. Microscopically, general congestion of the brains and internal organs was evident. Vibrio harveyi and V. alginolyticus were successfully isolated from the diseased fish. The isolated pathogens were found to be sensitive to oxytetracycline and tetracycline, but resistant towards ampicillin and vancomycin. Experimental infections using the isolated V. harveyi (108 CFU/mL), V. alginolyticus (108 CFU/mL), and concurrent infection by V. harveyi (108 CFU/mL) and V. alginolyticus (108 CFU/mL) in juvenile Asian Seabass Lates calcarifer resulted in 60, 100, and 100% mortality, respectively, within 240 h postinfection. The experimentally infected Asian Seabass demonstrated similar clinical signs and histopathological changes as the naturally infected hybrid groupers. However, concurrently infected fish demonstrated severe clinical signs and histopathological changes compared with single infections. These results suggest that both isolates of Vibrio are pathogenic to fish and responsible for the disease outbreak. However, concurrent infection involving V. alginolyticus and V. harveyi leads to a more devastating impact to the cultured fish. This is the first report of concurrent Vibrio infection in cultured marine fish in Malaysia

Detection, prevalence and antibiotic susceptibility profile of vibrio species isolated from Epinephelus species in Peninsular Malaysia

Infection of Vibrio species (spp.) among groupers (Epinephelus spp.) is one of the most reported diseases since it affects groupers’ production. Although it caused high mortality among groupers, a complete and up-to-date database on the prevalence and diversity of bacteria especially Vibrio spp. in groupers is not available in Malaysia. Thus, the objectives of this study were i) to characterize the bacterial diversity among cultured grouper and its culturing environment of seawater and sediment using a metagenomic approach, ii) to identify the prevalence and diversity of Vibrio spp. among cultured groupers in Peninsular Malaysia farms using the pyrH and gyrB genes, and iii) to determine the antimicrobial resistant profiles of Vibrio spp. In the metagenomic study, groupers’ liver, sediment and seawater samples were analyzed based on the 16S rRNA V3-V4 regions using the Illumina MiSeq platform. A total of 270 cultured groupers collected from nine farms in Peninsular Malaysia were used in the isolation and identification of Vibrio spp. based on the pyrH and gyrB genes. Then, the antimicrobial resistant profiles of Vibrio spp. isolates were determined using seven antibiotics such as ampicillin, penicillin, bacitracin, erythromycin, tetracycline, streptomycin and vancomycin. Results of the metagenomics test were generated 801,383 sequence reads and 9,308 operational taxonomic units (OTUs). The sediment showed the most diverse bacterial communities since it revealed the highest OTUs (7,378) compared to seawater (1,763) and liver of grouper (167). From the OTUs, phylum Proteobacteria was observed in the sediment (60%), seawater (54%) and liver (32%). Phylum Firmicutes was found only in the sediment and liver. Phylum Actinobacteria, Bacteroidetes, Cyanobacteria, Planctomycetes, and Chloroflexi were observed in sediment and seawater. Genus Vibrio and Photobacterium of phylum Proteobacteria were the only genera shared by the sediment, seawater and liver. Vibrio (77% - 96%) was dominantly present in the sediment and seawater compared to Photobacterium (2% - 7%). Similar Vibrio OTUs (denovo951 and denovo43955) were found in the sediment, seawater and liver indicating that there was a possible transmission of Vibrio between groupers and its surrounding environment. A study on the 270 cultured groupers collected from nine farms revealed that 380 Vibrio spp. were isolated from the pseudo-replicates of liver, spleen, and kidney of 195 (72%) cultured groupers. Results revealed that lesion was an early symptom of Vibrio infection since 82% of the cultured groupers were developed lesions on their skin, mouth and fins. A high number (25%) of the asymptomatic groupers were identified, thus, can be a Vibrio reservoir and threat to grouper farming. Vibrio spp. isolated from the groupers at the net cages was higher compared to the hatcheries. Analysis of the water quality is one of the contributor factors revealed that no correlation between the water quality parameters and increased number of Vibrio spp. at farms. Molecular analysis revealed that the pyrH gene was a superior phylomarker than the gyrB gene in identifying Vibrio spp. since it has high discriminatory power in differentiating species levels of Vibrio. Analysis of the phylogenetic tree of 380 pyrH sequences resulted in 13 Vibrio groups such as 28% of V. owensii, 25% of V. parahaemolyticus, 19% of V. alginolyticus, 14% of V. vulnificus, 3% of V. rotiferianus and Vibrio sp., 2% of V. campbellii, V. mytili and V. furnissii, and 1% of V. harveyi, V. diabolicus, V. fluvialis and V. tubiashii. Moreover, results revealed that groupers able to carry more than one Vibrio spp. simultaneously, thus, can enhance the mortality rate. Vibrio spp. also prone to infect the juvenile groupers rather than pre-adult groupers due to the immature immune systems developed. Analysis on the antimicrobial resistance profile suggested that ampicillin and penicillin G were ineffective in treating Vibrio infections since a high number (80%) of Vibrio spp. were resistant to both antibiotics. Effective monitoring on the administration of the bacitracin, erythromycin and vancomycin was required since 30% to 54% of the Vibrio isolates were found resistant to these antibiotics. Meanwhile, the resistance of Vibrio spp. to tetracycline and streptomycin was still low (14%). Most of the species included V. parahaemolyticus, V. alginolyticus, V. rotiferianus, V. campbellii and V. diabolicus were highly susceptible to both antibiotics. Multiple antibiotic resistance (MAR) index revealed that 88% of the Vibrio spp. had MAR index value of more than 0.2. Thus, the result indicated that the high number of Vibrio spp. were resistant to multiple antibiotics and continuously exposed to the antibiotics at the farms. Plasmid profiling results showed that 61% of Vibrio spp. were chromosomal-mediated with MAR index 0.37 and 39% were plasmid-mediated with MAR index 0.56. After the curing process, most of the Vibrio-positive plasmid were loss their resistance to antibiotics and the AMR index was reduced to 0.21. Thus, results indicated that the presence of problem can enhance the resistance of Vibrio spp. to antibiotics. In a conclusion, this study provided constructive documentation of bacterial communities in the groupers, sediment and seawater, prevalence of Vibrio infection among cultured groupers in Peninsular Malaysia, and occurrence of antibiotic resistance of Vibrio spp. presence in the cultured groupers

Customer perception towards staying at capsule hotel in Malaysia

This study focuses on customer perceptions towards staying at capsule hotels in Malaysia. The study examines the relationships among Servicescape, price, and location on customer perception towards staying at capsule hotels in Malaysia. Quantitative research is used in this study in order to accomplish this research. Convenience sampling is used, and responses from 384 respondents are collected in this research. To analyze all the data, descriptive analysis, reliability testing and Pearson correlation are used. The results support all the variables. This research contributes to understanding customer perception towards staying at capsule hotels in Malaysia. This research and data can be used as reference materials for industry stakeholders to design a better environment to facilitate customer’s experience toward staying at capsule hotels in Malaysia

Virulence-associated genes and antibiotic resistance patterns of Vibrio spp. isolated from cultured marine fishes in Malaysia

Background: Vibriosis is an important bacterial disease of cultured marine fishes worldwide. However, information on the virulence and antibiotic resistance of Vibrio spp. isolated from fish are scarce. This study investigates the distribution of virulence associated genes and antibiotic resistance patterns of Vibrio spp. isolated from cage-cultured marine fishes in Malaysia. Results: A total of 63 Vibrio spp. isolated from 62 cultured marine fishes in various geographical regions in Peninsular Malaysia were analysed. Forty-two of the isolates (66.7%) were positive for all chiA, luxR and vhpA, the virulence genes produced by pathogenic V. harveyi. A total of 62 Vibrio isolates (98%) had tlh gene of V. parahaemolyticus, while flaC gene of V. anguillarum was detected in 43 of isolates (68%). Other virulence genes, including tdh, trh, hlyA and toxRvc were absent from any of the isolates. Multiple antibiotic resistance (MAR) was exhibited in all strains of Harveyi clade, particularly against ampicillin, penicillin, polypeptides, cephems and streptomycin. The MAR index ranged between 0.06 and 0.56, and 75% of the isolates have MAR index of higher than 0.20. Host species and geographical origin showed no correlation with the presence of virulence genes and the antibiotic resistance patterns of Vibrio spp. Conclusions: The study indicates that majority of Vibrio spp. isolated from cultured marine fishes possess virulence genes, but were not associated with human pathogen. However, the antibiotics resistance is a real concern and warrants ongoing surveillance. These findings represent an updated knowledge on the risk of Vibrio spp. to human health, and also provides valuable insight on alternative approaches to combat vibriosis in cultured fish