Ahmed H. Al-Harbi

Seasonal variation in the intestinal bacterial flora of hybrid tilapia (Oreochromis niloticus×Oreochromis aureus) cultured in earthen ponds in Saudi Arabia

Abstract Seasonal quantitative and qualitative analyses of the bacterial flora associated with the intestine of hybrid tilapia ( Oreochromis niloticus × Oreochromis aureus ) cultured in earthen ponds in Saudi Arabia were carried out. The isolates were being identified to genus or species level. Total viable counts (TVC) of bacteria in the intestine varied between 6.8±1.9×10 6 to 7.5±1.4×10 7 colony forming units (cfu) g −1 in early summer, 1.6±2.0×10 6 to 5.1±2.5×10 7 cfu g −1 in summer, 3.1±1.4×10 8 to 1.3±2.2×10 9 cfu g −1 in autumn, and 8.9±1.8×10 5 to 1.3±0.9×10 7 cfu g −1 in winter. Altogether, 17 bacterial genera were identified from the intestine of tilapia. The bacteria were predominantly Gram-negative rods (77%). Aeromonas hydrophila , Shewanella putrefaciens , Corynebacterium urealyticum , Escherichia coli and Vibrio cholerae were the most abundant species with a prevalence of >10% in most cases except V. cholerae . Considerable numbers of Pseudomonas spp. were found only in winter. Photobacterium damselae , Pasteurella spp., Cellulomonus sp. and Bacillus sp. were present in some seasons of the year.

Nutrient budgets in tanks with different stocking densities of hybrid tilapia

Abstract Nitrogen and phosphorus budgets were estimated in 12 indoor fiberglass tanks stocked with hybrid tilapia (Oreochromis niloticus×O. aureus) at densities of 1 kg, 5 kg, 10 kg and 15 kg/m3 and reared for 14 days. Each density was replicated three times, and the experiment was repeated five times. The water in each tank was changed daily. Fish were fed a 34% protein tilapia feed to satiation twice daily. Feed consumption rate significantly decreased (P 0.05) among the treatments. The production of one kilogram of fish required 2.0–2.2 kg of feed in different stocking density treatments, while 87.1–95.6 g nitrogen and 12.6–13.8 g phosphorus were released into the water, as metabolic waste. Of the feed input, 21.4% of the nitrogen and 18.8% of the phosphorus were incorporated in the fish harvested.

Evaluation of three species of tilapia, red tilapia and a hybrid tilapia as culture species in Saudi Arabia

Abstract The culture potential of three pure tilapia species, Oreochromis niloticus , O. aureus, O. mossambicus , hybrid tilapia ( O. niloticus X O. aureus ) progeny and Taiwanese red tilapia ( O. mossambicus X O. niloticus ) was evaluated in 10 m 2 concrete tanks receiving freshwater. Tilapia were compared for growth, survival, yield, and feed conversion ratio. The different lines investigated showed different responses during different growing phases (fry, fingerling, sub-adult and adult). Final mean weights after 392 days rearing were higher for hybrid tilapia (327 g) than those of O. niloticus (293 g), red tilapia (264 g), O. aureus (234 g) and O. mossambicus (168 g). Yield ranged from 6.5 kg m −3 ( O. mossambicus ) to 13.0 kg m −3 (hybrid tilapia) and 2.2 to 4.4 kg 1 −1 of water used, respectively. The feeding of tilapia up to satiation within 30 min twice daily gave very good feed conversion ratios; the overall average ranged from 1.24 ( O. niloticus ) to 1.63 (red tilapia). Survival after four growing phases was 80% (hybrid tilapia), 74% ( O. niloticus ), 72% ( O. aureus ), 61% ( O. mossambicus ) and 7% (red tilapia). Overall performance, based on fry, fingerling, sub-adult and adult rearing and the ranking based on final mean weight, specific growth rate, survival, and yield proved hybrid tilapia to be the best candidate for intensive tank culture, closely followed by O. niloticus and O. aureus , O. mossambicus showed poor performance and red tilapia gave very low survival during the fry and larval rearing phases.

Production and characterization of monoclonal antibodies against tilapia Oreochromis niloticus immunoglobulin

Eight monoclonal antibodies (MAbs) against tilapia immunoglobulins (Ig) were produced and characterized. All of the MAbs are functional for use in enzyme-linked immunosorbent assays (ELISAs) and immunoblotting applications. Characterization of the MAbs for mouse Ig class and subclass indicate that four were IgG 2b, two were IgG 2a, one was IgG 3, and one was IgM K class. Western blot analysis of the eight hybridomas with purified Nile tilapia Ig indicated that all eight MAbs were heavy chain specific and further analysis indicated that all eight MAbs react with tilapia Ig H chain and cross-reactive with other tilapia species and their hybrids.

First isolation of Streptococcus sp. from hybrid tilapia (Oreochromis niloticus × O. aureus) in Saudi Arabia

Abstract The first documented epizootic of streptococcicosis has been recorded among cultured hybrid tilapia ( Oreochromis niloticus × O. aureus ) in Saudi Arabia. Affected fish showed erratic swimming, melanosis, exophthalmia, haemorrhaging around the jaws and at the base of the pectoral and dorsal fins and tail, and the presence of ascitic fluid in the adbominal cavity. The causal agent was characterized biochemically, and identified as an α-haemolytic Streptococcus sp.

Bacterial flora of polycultured common carp (Cyprinus carpio) and African catfish (Clarias gariepinus)

Quantitative and qualitative analyses of bacterial flora associated with pond water, gills, and intestine of polycultured healthy common carp (Cyprinus carpio) and African catfish (Clarias gariepinus) were carried out and identified to species level where possible. Total viable bacterial counts in the pond water ranged from 9.2 ± 5.5 × 103 to 6.6 ± 5.1 × 104 colony-forming units (cfu)/mL; in the gill filaments of carp and catfish, 3.3 ± 3.8 × 106 to 7.9 ± 5.6 × 106 and 1.1 ± 4.6 × 105 to 2.3 ± 5.2 × 106 cfu/g, respectively; and in the intestine of carp and catfish, 1.4 ± 2.9 × 1010 to 1.7 ± 6.0 × 1011 and 2.7 ± 3.4 × 1010 to 1.0 ± 4.5 × 1011 cfu/g, respectively. Gram-negative rod-shaped bacteria dominated the populations: 90% in carp, 89% in catfish, 80% in water, and 86% in the total populations. Altogether, 14 bacterial species of 10 genera were identified in total populations. Pond water bacteria had a reflection on the bacterial composition of the gills and intestine of carp and catfish. Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Staphylococcus sp., and Vibrio vulnificus appeared as the common bacteria in the populations, where the first three were highly significantly abundant (P < 0.0001). Moreover, A. hydrophila was the most significantly dominant bacteria (32%; P < 0.005) among the total populations. Pantoea sp. and Pasteurella pneumotropica were present only in carp and catfish, respectively, but Corynebacterium urealyticum and Micrococcus sp. were present only in pond water.

Aerobic Bacterial Flora of Common Carp (Cyprinus carpio L.) Cultured in Earthen Ponds in Saudi Arabia

ABSTRACT Quantitative and qualitative estimation of bacterial flora present in pond water, sediments, gills, and intestine of healthy common carp Cyprinus carpio cultured in Saudi Arabia were performed and identified to species level where possible. Mean total viable bacterial counts in pond water ranged from 1.2 ± 2.9 × 104 to 2.5 ± 3.5 × 105 cfu/mL; in sediments, 9.3 ± 2.1 × 107 to 2.7 ± 3.5 × 109 cfu/g; in gills filaments, 4.3 ± 2.9 × 106 to 1.6 ± 3.9 × 107 cfu/g; and in intestine, 8.7 ± 4.1 × 109 to 5.4 ± 3.2 × 1010 cfu/g. Gram-negative rod-shaped bacteria dominated (76%) the populations. In total, 12 bacterial genera and 15 species were identified. Pond water and sediment bacteria had the reflection on bacterial composition of gills and intestine of carp. Intestinal bacteria showed more diversification in contrast to gill bacteria. Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Corynebacterium urealyticum, Vibrio vulnificus, Vibrio sp., and Staphylococcus sp. were the common bacteria in all the populations. In pond water and carp intestine, A. hydrophila, S. putrefaciens, V. cholerae, and C. urealyticum were the most dominant bacteria (prevalence ≥ 10%) where pond sediments and the carp gills experienced with more one dominant bacterium V. vulnificus. Only the A. hydrophila covered one fourth (25%) of the total bacterial populations.

Bacterial Flora of Freshwater Prawn, Macrobrachium rosenbergii(de Man), Cultured in Concrete Tanks in Saudi Arabia

ABSTRACT Bacterial counts and the aerobic heterotrophic bacterial flora in the digestive tract of the freshwater prawn, Macrobrachium rosenbergii, in Saudi Arabia were investigated, and the isolates were identified to the species level. Physicochemical characteristics, bacterial counts, and bacterial flora of freshwater prawn culture tank water, tank sediment, and freshwater prawn carapace were also investigated. Total viable bacterial counts ranged from 8.9 ×103 to 1.4 ×105 cfu/mL; 3.4 ×106to4.1 ×108cfu/mL;2.1 ×103to4.7 ×104cfu/cm2and3.4 ×105 to 8.7 ×106 cfu/g in prawn culture tank water, tank sediment, carapace, and digestive tract of the freshwater prawn, respectively. In total, eleven bacterial species were identified. Chryseomonas sp., Vibrio diazo-trophicus, Shewanella putrefaciens, and Vibrio cholerae were the most abundant bacterial species (prevalence > 10%) in the tank water; Aeromonas enteropelogenes, Chryseomonas sp., and Pseudomonas alcaligenes in tank sediment; Aeromonas enteropelogenes, Vibrio diazotrophicus, Curtobacterium pusillum, Vibrio alginolyticus, and Chryseomonas sp. on freshwater prawn carapace, and Aeromonas enteropelogenes, Vibrio alginolyticus, and Pseudomonas alcaligenes in the digestive tract of the freshwater prawn.

Quantitative and Qualitative Bacterial Flora of Giant Freshwater Prawn Macrobrachium rosenbergii Cultured in Earthen Ponds in Saudi Arabia

Abstract Quantitative and qualitative analyses of bacterial flora associated with the digestive tract of the giant freshwater prawn Macrobrachium rosenbergii cultured in earthen ponds of Saudi Arabia were carried out. Bacterial counts and flora of prawn-culture pond water, sediment, and prawn carapaces, along with important physicochemical parameters, were investigated, and the isolates were identified to the genus or species level. Total viable counts (TVC; mean ± SD) varied between (1.0 ± 2.3) × 104 and (1.7 ± 0.8) × 105 colony-forming units (cfu) per milliliter in pond water, (5.8 ± 1.7) × 107 and (1.1 ± 2.9) × 109 cfu/g in sediment, (1.5 ± 0.9) × 105 and (1.6 ± 2.4) × 106 cfu/cm2 in the carapace, and (9.1 ± 1.5) × 106 and (8.7 ± 1.8) × 107 cfu/g in the digestive tract of freshwater prawns. The bacterial flora was predominantly gram-negative, accounting for 80% of total isolated strains. Altogether, 21 bacterial species of 16 genera were identified. Aeromonas hydrophila, Shewanella putrefaciens, other ...

Seasonal Trends in Gill Bacterial Flora of Hybrid Tilapia, Oreochromis niloticus × O. aureus

ABSTRACT Seasonal bacterial flora associated with the gills of hybrid tilapia, Oreochromis niloticus × O. aureus, cultured in earthen ponds were studied quantitatively and qualitatively for the first time in Saudi Arabia at quarterly intervals for one year. The recovered isolates were identified to species level where possible. Total viable counts (TVC) of bacteria in the gills ranged from 9.8±0.9 × 105 to 4.2±3.1× 106 colony forming units (cfu)/g of gills in spring, 3.9±1.7 × 106 to 1.1±2.4 × 107 cfu/g in summer, 6.5±2.3 × 106 to 4.2±2.6 × 107cfu/g in autumn, and 1.9±2.0 × 105 to 1.2±2.9 × 106 cfu/g in winter. In total, 15 bacterial genera were identified from the gills of tilapia and less diversification of bacterial genera (7) was observed in summer. The bacterial population was dominated by Gram-negative rods (77%). In all the seasons, Aeromonas hydrophila, Shewanella putrefaciens, Escherichia coli, and Corynebacterium sp. were the most abundant species with a prevalence of >10%. Aeromonas hydrophila was 26%, significantly higher (P < 0.005) in the population. Pseudomonas fluorescens was present in considerable number only during winter. Pseudomonas sp., Pasteurella sp., and Bacillus sp. were observed in most of the seasons. The variation of ambient seasonal temperature could account for some of the variation in the bacterial population.