Hassan Mohd Daud

Isolation, identification and characterization of Leuconostoc mesenteroides as a new probiotic from intestine of snakehead fish ( Channa striatus )

The intestinal microflora of snakehead ( Channa striatus ) fish was studied to isolate and identify lactic acid bacteria as new probiotic. A total of five lactic acid bacteria were isolated from intestine to evaluate with probiotic properties. Leuconostoc mesenteroides sp. mesenteroides with more ability to inhibit growth o f Aeromonas hydrophila was selected and identified by conventional and molecular techniques. This strain was able to survive and grow from pH 3 to 8 with the highest viability and growth rate at neutral conditions (pH 7). In addition, L. mesenteroides tolerated 0, 0.15 and 0.3% bile salt concentrations. This bacterium also, showed inhibitory activity against three tested fish pathogens which included; A. hydrophila, Pseudomonas aeruginosa and Shewanella putrefaciens . Antibiotic sensitivity test indicated that this strain was resistant to Streptomycin, intermediate to Amoxicillin and Kanamycin and sensitive to Gentamycin, Tetracycline, Chloramphenicol, and Ampicillin. Keywords : Isolation, characterization, probiotic, intestine, Leuconostoc mesenteroides , snakehead fish.

Detection and phylogenetic profiling of nodavirus associated with white tail disease in Malaysian Macrobrachium rosenbergii de Man.

White tail disease (WTD) is a serious viral disease in the hatcheries and nursery ponds of Macrobrachium rosenbergii in many parts of the world. A new disease similar to WTD was observed in larvae and post larvae of M. rosenbergii cultured in Malaysia. In the present study, RT-PCR assay was used to detect the causative agents of WTD, M. rosenbergii nodavirus (MrNV) and extra small virus (XSV) using specific primers for MrNV RNA2 and XSV. The results showed the presence of MrNV in the samples with or without signs of WTD. However, XSV was only detected in some of the MrNV-positive samples. Phylogenetic analysis showed that the RNA2 of our Malaysian isolates were significantly different from the other isolates. Histopathological studies revealed myofiber degeneration of the tail muscles and liquefactive myopathy in the infected prawns. This was the first report on the occurrence of MrNV in the Malaysian freshwater prawn.

White Mulberry (Morus alba) Foliage Methanolic Extract Can Alleviate Aeromonas hydrophila Infection in African Catfish (Clarias gariepinus)

Two experiments were simultaneously conducted with Morus alba (white mulberry) foliage extract (MFE) as a growth promoter and treatment of Aeromonas hydrophila infection in separate 60 and 30 days trail (Experiments 1 and 2, resp.) in African catfish (Clarias gariepinus). In Experiment 1, four diets, control and control supplemented with 2, 5, or 7 g MFE/kg dry matter (DM) of diet, were used. In Experiment 2, fish were intraperitoneally infected with Aeromonas hydrophila and fed the same diets as experiment 1 plus additional two diets with or without antibiotic. Results of experiment 1 showed that growth was unaffected by dietary levels of MFE. Treatments with the inclusion of MFE at the levels of 5 and 7 g/Kg DM had no mortality. Red blood cells (RBC), albumin, and total protein were all higher for the treatments fed MFE (5 and 7 g/Kg DM). Results of experiment 2 showed RBC, hemoglobin, hematocrit, globulin, albumin, and total protein improved with the increase in MFE in the infected fish. The dietary MFE at the level of 7 g/kg DM reduced mortality rate. In conclusion, MFE at the level of 7 g/kg DM could be a valuable dietary supplement to cure the infected fish.

Effect of Medium Composition and Culture Condition on the Production of Bacteriocin-Like Inhibitory Substances (BLIS) by Lactobacillus Paracasei LA07, a Strain Isolated from Budu

ABSTRACT The effect of medium composition (type and concentration of carbon and nitrogen sources) and culture conditions (pH, aeration and temperature) on the production of bacteriocin-like inhibitory substances (BLIS) by Lactobacillus paracasei LA07 was studied in shake flask culture. The highest BLIS production was obtained from de Man, Rogosa and Sharpe (MRS) broth, which was 4%, 22%, 51% and 63% higher than those obtained in M17 Broth, Tryptic Soy Broth (TSB), Brain Heart Infusion Broth (BHIB) and Nutrient Broth (NB) respectively. The addition of meat extract (5 g/L) and yeast extract (5 g/L) to MRS broth increased further BLIS production by 5% and 8%, respectively. The production of BLIS was further improved by 11% and 13% through the addition of tryptone (3 g/L) and glucose (10 g/L), respectively. The growth of Lb. paracasei LA07 and BLIS production were not significantly affected by agitation, either in anaerobic or in aerobic conditions. The optimum initial pH and temperature for BLIS production by Lb. paracasei LA07 was pH 8.5 and 30 °C, respectively.

The Effects of Vitex trifolia, Strobilanthes crispus and Aloe vera Herbal-mixed Dietary Supplementation on Growth Performance and Disease Resistance in Red Hybrid Tilapia ( Oreochromis sp.)

Herbs and herb mixtures have been used as a growth promotant in livestock and aquaculture production. The objective of the study was to evaluate the effect of a dietary herbal mix comprised of Vitex trifolia (VTE), Strobilanthes crispus (SCE) and Aloe vera (AVE) on the growth performance, disease resistance and histology of Oreochromis sp. for 60 days. The fishes were divided into i) control, infected fish, fed with normal diet and infected fishes treated with different herbal-mixed supplementation diets of ii) VTE and SCE iii) SCE and AVE iv) AVE and VTE. All experimental groups were challenged using with Streptococcus agalactiae (1 × 107 cfu/mL) via intraperitoneal route on day 46. On day 46th (pre-challenge) and 60th (post-challenge), five fish were randomly chosen from each tank for each experimental and control groups to blood collection. The cumulative mortality and survival rate were assessed every day. Tissues from kidney, liver and spleen were examined. The fish supplemented with herbal-mix with the combination of VTE and SCE and AVE and VTE showed improved growth performance. For haematological assays, RBC, Hb, and WBC were higher (P<0.05) in fish supplemented with these herb mix, while the alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were significantly affected by mixed-herbal supplementation. Histopathological examination of the organs revealed no negative effects in tissues. In conclusion, this study suggested that methanolic extracts of herbal mix composed of V. trifolia, S. crispus and A. vera extracts were effective as growth promoters and bacterial disease treatment in Oreochromis sp. when supplemented in daily diet.

Experimental infection of Aphanomyces invadans and susceptibility in seven species of tropical fish.

Aim: Epizootic ulcerative syndrome (EUS) causes by aquatic oomycete fungus, Aphanomyces invadans is a dangerous fish disease of a wide range of fresh and brackish water, wild and farmed fish throughout the world. The objective of the present study was to determine the susceptibility of a number of tropical fish species to the EUS and compare the severity of infection between experimental groups. Materials and Methods: Snakehead, Channa striata (Bloch, 1793); snakeskin gourami, Trichopodus pectoralis (Regan, 1910); koi carp, Cyprinus carpio (Linnaeus, 1758); broadhead catfish, Clarias macrocephalus (Günther, 1864); goldfish, Carassius auratus (Linnaeus, 1758); climbing perch, Anabas testudineus (Bloch, 1792); and Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) were challenged by intramuscular injection using zoospores of Aphanomyces invadans (NJM9701). The infected fish skins and muscles were examined for EUS histopathological characteristics, and the results on the severity of lesions and mortality were analyzed using SPSS program. Results: All zoospore-injected fish were shown to be susceptible to the EUS infection except Nile tilapia. Although, the general histopathological pattern was similar in the zoospore-injected group, but there were some variation in granulomatous reaction, that is the presence or absence of giant cells, and time of mortality were detected. The result of statistical analysis showed that there was a significant difference between species, (c2=145.11 and p<0.01). Conclusion: Gourami, koi carp, and catfish were demonstrated to be highly susceptible while goldfish and climbing perch were found to be moderately susceptible to the EUS infection. These findings suggested that the cellular response of fish to mycotic infection and granulomatous reaction varied in different fish species, which could not be an indicator of susceptibility or resistant to the EUS itself, although it was shown that the granulation rate and the level of maturity or solidification (consolidation of granulomas) were higher in resistant fish.

Histological features of the gastrointestinal tract of wild Indonesian shortfin eel, Anguilla bicolor bicolor (McClelland, 1844), captured in Peninsular Malaysia.

This study was conducted to record the histological features of the gastrointestinal tract of wild Indonesian shortfin eel, Anguilla bicolor bicolor (McClelland, 1844), captured in Peninsular Malaysia. The gastrointestinal tract was segmented into the oesophagus, stomach, and intestine. Then, the oesophagus was divided into five (first to fifth), the stomach into two (cardiac and pyloric), and the intestine into four segments (anterior, intermediate, posterior, and rectum) for histological examinations. The stomach had significantly taller villi and thicker inner circular muscles compared to the intestine and oesophagus. The lamina propria was thickest in stomach, significantly when compared with oesophagus, but not with the intestine. However, the intestine showed significantly thicker outer longitudinal muscle while gastric glands were observed only in the stomach. The histological features were closely associated with the functions of the different segments of the gastrointestinal tract. In conclusion, the histological features of the gastrointestinal tract of A. b. bicolor are consistent with the feeding habit of a carnivorous fish.

Ultrastructural analysis of Apicomplexa-Like parasites in two conch species Laevistrombus canarium and canarium urceus from Johor Straits, Malaysia

The tropical conch, Laevistrombus canarium (Linnaeus, 1758) and Canarium urceus (Linneaus, 1758) are ecologically and economically important shellfish species in Malaysia and neighboring region. Their populations, however are currently declining and this histopathological study investigates the aspect of parasitism and diseases that may affect their well-being. Conch samples were randomly collected from their natural habitat and histological sections (4-5 µm) of various organs and tissues were examined under light microscope. This was followed by ultrastructure analysis on infected tissues using transmission electron microscope (TEM). Based on the histological analysis, large numbers of gamonts, sporocysts and trophozoites of Apicomplexa-like parasites were observed in the vacuolated cells and pyramidal crypt cells of the digestive tubules, and in the digestive ducts. Furthermore, coccidian and oocysts-like Pseudoklossia sp. stages were also observed in the cells of the kidney. Apart from that, spores with cyst-like structure were observed in the digestive gland and kidney. Although the parasites were present in most of the organs analyzed, there was no obvious symptom, inflammatory response or mortality incurred on both species, which implies the possibility of a non-virulent relationship like commensalisms or mutualism. However, more investigations, including molecular studies, are needed to confirm the parasite identification and dynamics, and to further evaluate the nature of relationship between Apicomplexa parasites and their host.