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| Articles
by
Mohamed Shariff |
Total Records (
4 ) for
Mohamed Shariff |
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Fatimah Md. Yusoff
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Hazel Matias-Peralta
and
Mohamed Shariff
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Six shrimp culture ponds of 1 ha each, located between 101° 22' E 2° 49'N -101° 22' E 3° 17'N, were used to elucidate the effects of using eutrophic waters on phytoplankton communities. Three ponds were filled with unpolluted water, while the other three received eutrophic water. Water quality and phytoplankton populations were analyzed fortnightly over a period of 110 days to coincide with the shrimp culture cycle. In ponds with eutrophic water, the cyanobacteria (nine species) were the dominant phytoplankton group (>90% of the total phytoplankton density), followed by the green algae (seven species) and diatoms (six species). Ponds with originally unpolluted water were dominated by the diatoms with 18 species, followed by the cyanobacteria (six species) and one species of green algae. Shrimp production in ponds with unpolluted water was significantly higher (4,877.4 ± 438.5 kg ha-1 when compared to 1,385.0 ± 243.8 kg ha-1 in ponds using eutrophic water. This study illustrated that initial water quality supply influenced the phytoplankton dominance, which in turn determined the aquaculture production in shrimp culture ponds. |
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Sanjoy Banerjee
,
Lee Mei Kim
,
Mohamed Shariff
,
Helena Khatoon
and
Fatima Md. Yusoff
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The use of antibiotics in aquaculture to treat infections has resulted in the development of resistant strains which have rendered antibiotic treatment ineffective. Therefore, alternative antibacterial materials must be found. Extracts of neem tree (Azadirachta indica) leaves were tested against Vibrio parahaemolyticus and Vibrio alginolyticus isolated from cultured shrimp. Aqueous extract of neem leaves did not produce any inhibitory zone while the neem juice produced inhibitory zone that showed linear relationship to the concentration of neem juice on both bacteria. The Minimum Inhibitory Concentration (MIC) for V. parahaemolyticus and V. alginolyticus was 3.13 and 6.25%, respectively. The Minimum Bactericidal Concentration (MBC) for V. parahaemolyticus and V. alginolyticus was 12.50 and 25.00%, respectively. It is concluded that neem juice is an antibacterial agent and is useful for inhibition of vibrios in shrimp. |
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N. Maya Erna
,
Sanjoy Banerjee
,
Mohamed Shariff
and
Fatimah Md. Yusoff
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The immobilization of nitrifying bacteria in alginate has been used to evaluate the performance of ammonia reduction. In this research, bacteria were screened and observed for their ability to reduce ammonia. Consortium M1, isolated from the mangrove area (Morib, Selangor) showed the most effective reduction of ammonia from an initial concentration of 2.17±0.10 to 0.06±0.01 mg L-1 in 14 days. The consortium was then identified to consist of Pseudomonas aeruginosa (99%), Pseudomonas stutzeri (98%) and Nocardioides albus (98%) using the 16S rDNA gene sequences via Polymerase Chain Reaction (PCR) technique and identified by phylogenetic analysis based on their partial 16S rDNA sequences comparison in NCBI GenBank. The consortium M1 was then immobilized into alginate beads each containing 1.79x103 CFU mL-1 bacteria cells before being tested for its efficacy in reducing ammonia under laboratory conditions using 10, 20, 30, 40, 50, 100, 150 and 200 beads. The fastest reduction rate of Total Ammonia Nitrogen (TAN) was observed in flasks containing 150 beads which on day 6, drastically reduced TAN from 2.50±0.10 to 0.090±0.059 mg L-1 followed by treatment with 200 beads (0.104±0.07 mg L-1). However, at the end of experiment at day 14, the lowest TAN level (0.083±0.063 mg L-1) was observed in flasks with 200 beads which was not significantly different (p>0.05) from flasks with 150 beads (0.106±0.034 mg L-1). The present study reveals that the immobilization of bacterial consortium consisting of ammonia oxidizing bacteria could be used as an alternative for reduction of high TAN concentration in shrimp or fish hatchery system. |
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Nurul Salma Adenan
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Fatimah Md. Yusoff
and
Mohamed Shariff
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Salinity and temperature are two of the major factors controlling the growth
rate of microalgae. In this study, the effect of salinity and temperature on
the growth of marine microalgae; an unidentified Chlorella sp. and Chaetoceros
calcitrans were investigated to optimize the microalgal biomass production.
These species were cultured at different salinities (20, 25 and 30‰) and
temperatures (20, 25 and 30°C). C. calcitrans and Chlorella sp.
had significantly higher (p<0.05) growth rate when cultured at salinities
of 30 and 25‰, respectively. In terms of temperature, the highest (p<0.05)
growth rate was observed in C. calcitrans and Chlorella sp. cultivated
at temperatures of 30 and 25°C, respectively. This study indicated that
C. calcitrans was suitable to marine condition, whereas Chlorella
sp. showed optimum growth at lower salinity and temperature. |
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