This paper reports a case of natural co-infection of Tilapia Lake Virus (TiLV) and Aeromonas veronii in a Malaysian red hybrid tilapia (Oreochromis niloticus × O. mossambicus) farm. In May 2017, a tilapia farm operator reported a mass mortality among cultured red hybrid tilapia juveniles, approximately 45 days after introduction into earthen ponds. Affected fish showed lethargy, loss of appetite, swim near the pond edge, pale and isolated from schooling group. There were skin redness and haemorrhages, particularly at the operculum area and at the base of dorsal, caudal and anal fins. Histopathological examinations revealed swollen hepatocytes, haemorrhagic spleens and perivascular cuffing consisted of mononuclear cells in the brains. PCR and sequence analyses confirmed the presence of TiLV and A. veronii in the diseased fish. Phylogenetic tree revealed that Malaysian's TiLV strain was more closely related with the virus isolated in Israel than in Egypt or Thailand, while Malaysian's A. veronii strain 5L was closely related with strains from China. TiLV infection is a significant threat to global tilapia industry. However, synergistic co-infection of TiLV and other bacterial might aggravate the problem.

Bacteria are present in stingless bee nest products. However, detailed information on their characteristics is scarce. Thus, this study aims to investigate the characteristics of bacterial species isolated from Malaysian stingless bee, Heterotrigona itama, nest products. Honey, bee bread and propolis were collected aseptically from four geographical localities of Malaysia. Total plate count (TPC), bacterial identification, phenotypic profile and enzymatic and antibacterial activities were studied. The results indicated that the number of TPC varies from one location to another. A total of 41 different bacterial isolates from the phyla Firmicutes, Proteobacteria and Actinobacteria were identified. Bacillus species were the major bacteria found. Therein, Bacillus cereus was the most frequently isolated species followed by Bacillus aryabhattai, Bacillus oleronius, Bacillus stratosphericus, Bacillus altitudinis, Bacillus amyloliquefaciens, Bacillus nealsonii, Bacillus toyonensis, Bacillus subtilis, Bacillus safensis, Bacillus pseudomycoides, Enterobacter asburiae, Enterobacter cloacae, Pantoea dispersa and Streptomyces kunmingensis. Phenotypic profile of 15 bacterial isolates using GEN III MicroPlate™ system revealed most of the isolates as capable to utilise carbohydrates as well as amino acids and carboxylic acids and derivatives. Proteolytic, lipolytic and cellulolytic activities as determined by enzymatic assays were detected in Bacillus stratosphericus PD6, Bacillus amyloliquefaciens PD9, Bacillus subtilis BD3 and Bacillus safensis BD9. Bacillus amyloliquefaciens PD9 showed broad-spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria in vitro. The multienzymes and antimicrobial activities exhibited by the bacterial isolates from H. itama nest products could provide potential sources of enzymes and antimicrobial compounds for biotechnological applications.

Bacteria with the ability to tolerate, remove, and/or degrade several xenobiotics simultaneously are urgently needed for remediation of polluted sites. A previously isolated bacterium with sodium dodecyl sulfate- (SDS-) degrading capacity was found to be able to reduce molybdenum to the nontoxic molybdenum blue. The optimal pH, carbon source, molybdate concentration, and temperature supporting molybdate reduction were pH 7.0, glucose at 1.5% (w/v), between 25 and 30 mM, and 25°C, respectively. The optimum phosphate concentration for molybdate reduction was 5 mM. The Mo-blue produced exhibits an absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. None of the respiratory inhibitors tested showed any inhibition to the molybdenum-reducing activity suggesting that the electron transport system of this bacterium is not the site of molybdenum reduction. Chromium, cadmium, silver, copper, mercury, and lead caused approximately 77, 65, 77, 89, 80, and 80% inhibition of the molybdenum-reducing activity, respectively. Ferrous and stannous ions markedly increased the activity of molybdenum-reducing activity in this bacterium. The maximum tolerable concentration of SDS as a cocontaminant was 3 g/L. The characteristics of this bacterium make it a suitable candidate for molybdenum bioremediation of sites cocontaminated with detergent pollutant.

As a major food crop, rice (Oryza sativa) is produced and consumed by nearly 90% of the population in Asia with less than 9% produced outside Asia. Hence, reports on large scale grain losses were alarming and resulted in a heightened awareness on the importance of rice plants’ health and increased interest against phytopathogens in rice. To serve this interest, this review will provide a summary on bacterial rice pathogens, which can potentially be controlled by plant growth-promoting bacteria (PGPB). Additionally, this review highlights PGPB-mediated functional traits, including biocontrol of bacterial rice pathogens and enhancement of rice plant’s growth. Currently, a plethora of recent studies address the use of PGPB to combat bacterial rice pathogens in an attempt to replace existing methods of chemical fertilizers and pesticides that often lead to environmental pollutions. As a tool to combat bacterial rice pathogens, PGPB presented itself as a promising alternative in improving rice plants’ health and simultaneously controlling bacterial rice pathogens in vitro and in the field/greenhouse studies. PGPB, such as Bacillus, Pseudomonas, Enterobacter, Streptomyces, are now very well-known. Applications of PGPB as bioformulations are found to be effective in improving rice productivity and provide an eco-friendly alternative to agroecosystems.

BackgroundNumerous prevalence studies of Vibrio spp. infection in fish have been extensively reported worldwide, including Malaysia. Unfortunately, information on the prevalence of Vibrio spp. in groupers (Epinephelus spp.) is limited. In this study, groupers obtained from nine farms located at different geographical regions in Malaysia were sampled for the presence of pathogenic Vibrio spp. and their susceptibility profiles against seven antibiotics.ResultsOut of 270 grouper samples, 195 (72%) were detected with the presence of Vibrio spp. Vibrio communis showed highest prevalence in grouper (28%), followed by V. parahaemolyticus (25%), V. alginolyticus (19%), V. vulnificus (14%), V. rotiferianus (3%), Vibrio sp. (3%), V. campbellii (2%), V. mytili (2%), V. furnissii (2%), V. harveyi (1%), V. tubiashii (1%), V. fluvialis (0.3%) and V. diabolicus (0.3%). Assessment on the antibiotic susceptibility profiles of the Vibrio spp. revealed that majority of the isolates were susceptible to tetracycline, streptomycin, erythromycin and bacitracin, but resistance to ampicillin, penicillin G and vancomycin. The mean MAR index of the Vibrio isolates was 0.51, with 85% of the isolates showed MAR index value of higher than 0.2. Results indicate that the Vibrio spp. were continuously exposed to antibiotics. Furthermore, the plasmid profiles of Vibrio spp. showed that 38.7% of the isolates harbored plasmid with molecular weight of more than 10 kb, while 61.3% were without plasmid. During curing process, Vibrio spp. lost their plasmid, but remained resistant to ampicillin, penicillin G, bacitracin and vancomycin while a few isolates remained resistant to erythromycin, streptomycin and tetracycline. The results suggested that the resistance to antibiotics in isolated Vibrio spp. might be due to chromosomal and plasmid borne.ConclusionsThis study demonstrates the prevalence of Vibrio spp. in groupers and the distribution of multidrug resistance strains that could be of concern to the farmers in Malaysia. In addition, data from this study can be further used in fish disease management plan.