Mohd Salleh Kamarudin

Anthropogenic impacts on heavy metal concentrations in the coastal sediments of Dumai, Indonesia

Concentrations of Cd, Cu, Pb, Zn, Ni and Fe were determined in the surface sediments to investigate the distributions, concentrations and the pollution status of heavy metals in Dumai coastal waters. Sediment samples from 23 stations, representing 5 different site groups of eastern, central and western Dumai and southern and northern Rupat Island, were collected in May 2005. The results showed that heavy metal concentrations (in μg/g dry weight; Fe in %) were 0.88 (0.46–1.89); 6.08 (1.61–13.84); 32.34 (14.63–84.90); 53.89 (31.49–87.11); 11.48 (7.26–19.97) and 3.01 (2.10–3.92) for Cd, Cu, Pb, Zn, Ni and Fe, respectively. Generally, metal concentrations in the coastal sediments near Dumai city center (eastern and central Dumai) which have more anthropogenic activities were higher than those at other stations. Average concentration of Cd in the eastern Dumai was slightly higher than effective range low (ERL) but still below effective range medium (ERM) value established by Long et al. (Environmental Management 19(1):81–97, 1995; Environmental Toxicology Chemistry 17(4):714–727, 1997). All other metals were still below ERL and ERM. Calculated enrichment factor (EF), especially for Cd and Pb, and the Pollution load index (PLI) value in the eastern Dumai were also higher than other sites. Cd showed higher EF when compared to other metals. Geo-accumulation indices (Igeo) in most of the stations (all site groups) were categorized as class 1 (unpolluted to moderately polluted environment) and only Cd in Cargo Port was in class 2 (moderately polluted). Heavy metal concentrations found in the present study were comparable to other regions of the world and based on the calculated indices it can be classified as unpolluted to moderately polluted coastal environment.

Influence of live and artificial diets on tissue composition and trypsin activity in Penaeus japonicus larvae

Abstract Penaeus japonicus larvae were reared using live food, an artificial diet or an artificial diet plus C. gracilis . Larvae from all treatments were equivalent in weight and length at the third protozoeal stage, but mysis and postlarvae from both the live food and the artificial diet plus C. gracilis treatments were significantly larger and reached metamorphosis earlier than those fed the artificial diet alone. There were significant increases in percentage nitrogen and carbon contents during development in larvae fed the live food or the artificial diet plus C. gracilis , but not of larvae fed the artificial diet alone. High growth and nitrogen and carbon retention in mysis larvae fed live food was accompanied by a drop in trypsin activity. Despite a strong trypsin response to the artificial diet, mysis larvae appear unable to assimilate sufficient dietary protein to support growth equivalent to that observed in larvae fed live food. Supplementing the artificial diet with a low density of C. gracilis produced postlarvae of the same size and tissue composition as those reared using live food. It is suggested that the algal co-feed contributes either extra digestible nutrients or some specific growth-enhancing factor(s).

Selection and identification of non-pathogenic bacteria isolated from fermented pickles with antagonistic properties against two shrimp pathogens

In this study, potential probiotic strains were isolated from fermented pickles based on antagonistic activity against two shrimp pathogens (Vibrio harveyi and Vibrio parahaemolyticus). Two strains L10 and G1 were identified by biochemical tests, followed by16S ribosomal RNA gene sequence analysis as Bacillus subtilis, and characterized by PCR amplification of repetitive bacterial DNA elements (Rep-PCR). Subsequently, B. subtilis L10 and G1 strains were tested for antibacterial activity under different physical conditions, including culture medium, salinity, pH and temperature using the agar well diffusion assay. Among the different culture media, LB broth was the most suitable medium for antibacterial production. Both strains showed the highest level of antibacterial activity against two pathogens at 30 °C and 1.0% NaCl. Under the pH conditions, strain G1 showed the greatest activity against V. harveyi at pH 7.3–8.0 and against V. parahaemolyticus at pH 6.0–8.0, whereas strain L10 showed the greatest activity against two pathogens at pH 7.3. The cell-free supernatants of both strains were treated with four different enzymes in order to characterize the antibacterial substances against V. harveyi. The result showed considerable reduction of antibacterial activity for both strains, indicating the proteinaceous nature of the antibacterial substances. A wide range of tolerance to NaCl, pH and temperature was also recorded for both strains. In addition, both strains showed no virulence effect in juvenile shrimp Litopenaeus vannamei. On the basis of these results and safety of strains to L. vannamei, they may be considered for future challenge experiments in shrimp as a very promising alternative to the use of antibiotics.

Nitrogenous excretion of Penaeus monodon postlarvae fed with different diets

Abstract This study is designed to determine ammonia and nitrite excretion by Penaeus monodon 25–30 day old postlarvae fed with different diets (artificial and natural). Shrimps were fed with Chaetoceros calcitrans (phytoplankton), chironomid larvae (benthos), Brachionus sp. (rotifer) and artificial diet. In the control treatment, shrimps were not fed. The highest concentration of ammonia was excreted by shrimps fed with artificial diet and the lowest by that of control treatment. All treatments except where shrimps fed on C. calcitrans showed a sudden increase in ammonia-N excretion after 36 h. C. calcitrans contributed to high ammonia excretion only after 61 h. Shrimps fed with Brachionus sp. (rotifer) showed significantly higher nitrite excretion rate compared to other treatments. Shrimps fed on C. calcitrans depicted the lowest nitrite excretion. This experiment indicated that nitrogenous excretion was predominant in shrimps fed with artificial diets. Live food like algae and chironomids, despite a high protein content, contribute to low nitrogenous excretion and hence pose less adverse effects on water quality compared to artificial diets.

Dietary Lipid Levels Affect Growth and Fatty Acid Profiles of Malaysian Mahseer Tor tambroides

Abstract After protein, the second major essential macronutrient in fish diet is lipid. This study was conducted to determine the optimum level of dietary lipid for the best growth performance of juvenile Malaysian mahseer Tor tambroides. Four isonitrogenous diets containing 40% crude protein were formulated to contain different levels of lipid (5, 10, 15, or 20% on an as-fed basis). Cod liver oil was incorporated into the feed as the main dietary lipid source used to formulate the diets while residual oil coming from other ingredients contributed about 5% of dietary lipid. The experimental diets were labeled as L5, L10, L15, or L20 to denote the levels of dietary lipid. Fish were fed the experimental diets in triplicate groups for 63 d. Growth performance, survival rate, and daily feed intake by Malaysian mahseer significantly decreased when fed diets in which levels of dietary lipid increased from 5% to 20%. However, the growth performance did not vary significantly between fish fed the L5 and L10 diets...

Changes over time in muscle fatty acid composition of Malaysian mahseer, Tor tambroides , fed different dietary lipid percentage

The effects of four isonitrogenous diets containing different lipid levels on the muscle fatty acid profiles of Malaysian mahseer were evaluated over a period of six weeks from June to July, 2010. A general increase of monounsaturated fatty acid contents in the muscle of fish that were fed the test diets was detected after two weeks. Despite the high total content of long chain n-3 polyunsaturated fatty acid (PUFA) in the formulated diets, the levels of these fatty acids in the muscle did not increase and it may be speculated that the content of long chain n-3 PUFAs in this species was determined by desaturation and elongation of shorter chain fatty acids rather than direct absorption from the diet. Moreover, reduction of muscle n-3 PUFA content after six weeks of feeding showed that a diet containing high level of n-3 PUFA may not be able to provide all the essential fatty acid requirements of T. tambroides .

Evaluation of in vitro Vibrio static activity of Shewanella algae isolated from healthy Penaeus monodon

To conquer disease problem in shrimp industries, probiotic biocontrol is a well known remedy now. The antagonistic ability of separated isolates from different parts of juvenile Penaeus monodon were screened against shrimp Vibrio pathogens; Vibrio parahaemolyticus and Vibrio alginolyticus. The most antagonistic effect was observed for an isolate that was primarily identified as Shewanella algae using conventional methods followed by Biolog microlog software. Since production of antagonistic agents rely on cultural conditions, antagonistic ability of candidate probioic against the mentioned Vibrios was assessed using Response Surface Methodology, with central composite design in which four independents variables were assumed: temperature (10 - 50°C), pH (6 -10), NaCl concentration (0 - 50%) and time (12 – 60 h). The coefficients of multiple determinations (R2), for the responses of antagonistic effect of S. algae against V. parahaemolyticus and V. alginolyticus values were 0.807 and 0.805, respectively. Concentration of the NaCl exhibited least influence on the antibacterial effect of candidate probiotic while the other independent variables exhibited different degree of affect. The candidate probiotic revealed a reasonable antibacterial response in quite a wide range of temperature and pH in which the maximum levels were in the same range of optimum shrimp culture.

Improvement of feed pellet characteristics by dietary pre-gelatinized starch and their subsequent effects on growth and physiology in tilapia

A 9-week study was conducted to compare dietary corn starch (CS) or tapioca starch (TS), with or without being pre-gelatinized (PG), on the growth, feeding efficiencies, plasma and muscle biochemistry, intestinal short chain fatty acids (SCFA), and liver glycogen of triplicate groups of 20 red hybrid tilapia (Orecohromis sp.). Various pellet characteristics were evaluated, along with their surface and cross sectional microstructure. The PG diets had significantly higher water stability, bulk density, and protein solubility, along with a smoother surface. Tilapia fed the TS diet had lower growth than had all other tilapia, but were significantly improved when diet was pre-gelatinized. In the PG treatments, intestinal SCFA significantly decreased while plasma glucose, cholesterol and triglycerides, as well as liver glycogen, significantly increased. Fish fed the CS diet had significantly more long chain polyunsaturated fatty acid than had those fed by other treatments. Pre-gelatinization may improve fish productivity and offer greater flexibility during aquafeed production.

Trypsin-modulating oostatic factor (TMOF) decreased the survival, growth and digestion enzymes of Macrobrachium rosenbergii

Trypsin-modulating oostatic factor (TMOF) is an effective mosquito larvicide, but information on its potential toxicity to non-target organisms is limited. To investigate this, triplicate groups of 10 Macrobrachium rosenbergii were exposed to 0, 10, 50 or 100 mg/L nominal TMOF concentrations for 12 days. Tail moisture, crude protein, and hepatopancreatic glycogen/histopathology were unaffected, but increasing TMOF linearly decreased survival and growth. TMOF at the lowest concentration employed significantly decreased trypsin and chymotrypsin activities.

Detection and identification of antibiotic biosynthesis genes in Bacillus subtilis strains

Two Bacillus subtilis strains L10 and G1, previously isolated from fermented pickles, were tested for antibacterial activity against Vibrio harveyi using a well-diffusion agar assay. Antibiotic biosynthesis genes were then detected in both bacterial strains and included the following genes: bacA, bacB and bacD genes for bacilysin production, ppsE/fenB gene for plipastatin/fengycin production, albF and albA genes for subtilosin production, and srfAB and sfP genes for surfactin production. Based on these results, two B. subtilis strains could be considered as potential biological control agents in aquaculture.