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.     

Assessment of prebiotic potentials in selected leaf meals of high dietary fibre on growth performance,body composition,nutrient utilization and amylase activities of a tropical commercial carp fingerlings

The performance of selected leaf meals of high dietary fibre in the feed of a tropical commercial carp, hybrid lemon fin barb (Barbonymus gonionotus ♀ × Hypsibarbus wetmorei ♂) was evaluated in a 56‐day feeding trial. The tropical carp juveniles (9.43 ± 0.05 g) were randomly stocked in 60‐L aquaria at 15 fish per aquarium. Five isonitrogenous and isocaloric diets (30% crude protein, 17 kJ/g gross energy) containing no leaf meal and 10% napier grass (Pennisetum purpureum), alfalfa (Medicago sativa), water spinach (Ipomea aquatica) and Gliricidia sepium leaf meals were formulated and tested. Three aquaria were randomly assigned to each experimental diet. The results showed that fish‐fed diets containing leaf meals showed superior growth performance and body composition which was better than those fed control diet. The leaf meal‐treated groups also had higher values of protein, lipid, energy retention and production of digestive enzymes amylase. Conclusively, the results indicated that leaf meal fibre provided better performance showing the inherent prebiotic effect of the utilization of these leaf meal in hybrid lemon fin barb .     

Pantoea: a newly identified causative agent for leaf blight disease in rice

Journal of Plant Diseases and Protection - Leaf blight is one of the most serious threats to rice agroecosystems worldwide, and the yield reduction due to this disease can be as high as 70%. For...     

Anti-inflammatory activities of cucurbitacin E isolated from Citrullus lanatus var. citroides: role of reactive nitrogen species and cyclooxygenase enzyme inhibition

The in vivo and in vitro mechanistic anti-inflammatory actions of cucurbitacin E (CE) (Citrullus lanatus var. citroides) were examined. The results showed that LPS/INF-γ increased NO production in RAW264.7 macrophages, whereas L-NAME and CE curtailed it. CE did not reveal any cytotoxicity on RAW264.7 and WRL-68 cells. CE inhibited both COX enzymes with more selectivity toward COX-2. Intraperitoneal injection of CE significantly suppressed carrageenan-induced rat's paw edema. ORAC and FRAP assays showed that CE is not a potent ROS scavenger. It could be concluded that CE is potentially useful in treating inflammation through the inhibition of COX and RNS but not ROS.     

Antiparasitic activity of the medicinal plant Dillenia suffruticosa against the marine leech Zeylanicobdella arugamensis (Hirudinea) and its phytochemical composition

Zeylanicobdella arugamensis (Annelida: Hirudinea), a marine parasitic leech, is currently affecting different species of cultured groupers, hybrid groupers, snappers and sea bass in Malaysia. Dillenia suffruticosa (Dilleniaceae), a medicinal plant found in Sabah, has been selected in our experiment to kill the leeches as a natural control method. The leech‐infested hybrid groupers were collected from aquaculture facilities, and the isolated leeches were challenged against methanol extract of D. suffruticosa leaves. The experiment was carried out using various concentrations of the extracts such as 25, 50 and 100 mg/ml. The methanol extract showed significant antiparasitic activity against Z. arugamensis with 100% mortality at a concentration of 100 mg/ml in 14.39 ± 3.75 min., followed by 50 and 25 mg/ml in 32.97 ± 9.29 and 41.77 ± 5.40 min., respectively. The phytochemical composition of the extract was determined using GC‐MS analysis to understand the nature of the principal compounds responsible for its antiparasitic properties. The leaves of D. suffruticosa demonstrated the presence of different bioactive compounds of various natures with varying percentages. Thus, it could be revealed that the methanol extract of D. suffruticosa mainly contains vital phytochemical compounds and showed an effective antiparasitic activity against the harmful leeches of hybrid groupers.     

Biological filtration properties of selected herbs in an aquaponic system

This study was conducted to determine the biological filtration capabilities of some culinary herbs co‐cultured with lemon fin barb hybrid in a nutrient film technique (NFT) recirculating aquaponic system. Lemon fin barb hybrid (Hypsibarbus wetmorei ♂ × Barbonymus gonionotus ♀) fingerlings were stocked in twelve 2‐tonne fibreglass tanks at 25 fish per tank and co‐cultured with Chinese celery (Apium graveolens var. secalinum Alef.), coriander (Coriandrum sativum) and peppermint (Mentha × piperita) for seven weeks. The impacts of the waste generated by the fish on the water quality, the filtration capability of the herbs and the ability of fish and herbs to retain nutrients (NPK) were also estimated. All the herbs showed water purifying potentials to varying degrees as significantly lower levels of nitrogenous compounds (NH₃‐N, NO₃‐N, NO₂‐N) were observed after the herbal filtration. The plant growth seemed to be affected by their ability to absorb nutrients and consequently purify the culture medium. Interestingly, the lemon fin barb hybrid also showed significant differences in terms of weight gain, but the nutrient retention among fish treatments was not statistically different. The plants absorbed less phosphorus and potassium than the fish. After computing for the total system percentage of NPK recovered, nitrogen was the most retained nutrient. The peppermint showed superiority in terms of gross biomass and water purifying potential compared to the Chinese celery and coriander.     

Comparative genome analysis reveals a distinct influence of nucleotide composition on virus–host species‐specific interaction of prawn‐infecting nodavirus

Discovery of species‐specific interaction between the host and virus has drawn the interest of many researchers to study the evolution of the newly emerged virus. Comparative genome analysis provides insights of the virus functional genome evolution and the underlying mechanisms of virus–host interactions. The analysis of nucleotide composition signified the evolution of nodavirus towards host specialization in a host‐specific mutation manner. GC‐rich genome of betanodavirus was significantly deficient in UpA and UpU dinucleotides composition, whilst the AU‐rich genome of gammanodavirus was deficient in CpG dinucleotide. The capsid of MrNV and PvNV of gammanodavirus retains the highest abundance of adenine and uracil at the second codon position, respectively, which were found to be very distinctive from the other genera. ENC‐GC3 plot inferred the influence of natural selection and mutational pressure in shaping the evolution of MrNV RdRp and capsid, respectively. Furthermore, CAI/eCAI analysis predicts a comparable adaptability of MrNV in squid, Sepia officinalis than its natural host, Macrobrachium rosenbergii. Thus, further study is warranted to investigate the capacity of MrNV replication in S. officinalis owing to its high codon adaptation index.     

Functional properties and characterization of dietary fiber from Mangifera pajang Kort. fruit pulp

A dried high fiber product from bambangan (Mangifera pajang Kort.) fruit pulp was prepared and evaluated for proximate composition, functional properties, and soluble and insoluble dietary fiber composition. Mangifera pajang fibrous (MPF) consisted of 4.7% moisture, 0.8% fat, 4% protein, and 30 mg total polyphenol per g of dry sample, and 9, 79 and 88% soluble, insoluble and total dietary fiber, respectively. Water holding capacity, oil holding capacity, swelling, and solubility were found to be 9 g/g dry sample, 4 g/g dry sample, 16 mL/g dry sample, and 11%, respectively. The glucose dialysis retardation index of MPF was approximately double that of cellulose fiber. Soluble dietary fiber contained mannose, arabinose, glucose, rhamnose, erythrose, galactose, xylose, and fucose at 1.51, 0.72, 0.39, 0.16, 0.14, 0.05, 0.04, and 0.01%, respectively, with 5.8% uronic acid, while insoluble dietary fiber was composed of arabinose (18.47%), glucose (4.46%), mannose (3.15%), rhamnose (1.65%), galactose (1.20%), xylose (0.99%), and fucose (0.26%) with 15.5% uronic acid and 33.1% klason lignin. These characteristics indicate that MPF is a rich source of dietary fiber and has physicochemical properties which make it suitable as an added ingredient in various food products and/or dietetic, low-calorie high-fiber foods to enhance their nutraceutical properties.