الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 229 |  |  |
| | | from | 229 | | |
Abstract
Environmental pollution is one of the most deleterious agents to the biological life. Fish in ponds, lakes and rivers cannot avoid exposure to that pollution, whether it is chemicals suspended or dissolved in water, being less than land animals to move to favorable regions to avoid unfavorable conditions. Egyptian lakes act as temporary reservoirs for industrial and agricultural wastewater.
This study aims to evaluate and compare the chemical and bacteriolocal quality of water and fish in Qaroun lake (closed) and El-Manzala lake (semi-closed). In addition, investigate the antibacterial activity of silver and zinc oxide nanoparticles combined with antibiotics against Gram-negative and Gram-positive pathogenic bacteria isolated from two lakes. Furthermore, assessment of DNA damage in fish captured from two lakes.
In the following study; physicochemical parameters were measured in water collected from two lakes. In case of Qaroun lake the temperature, pH and salinity average measurements were: 23°C, 7.8, 23.5 g/l, respectively. While, the average levels of DO and COD were 6.4, 114.5 mg O2/l, respectively. On the other hand, the average levels of ammonia, nitrite, nitrate and total phosphorus were 0.74, 0.32, 0.88 mg N/l and 0.75 mg P/l, respectively.
In case of water collected from El-Manzala lake; physicochemical parameters were detecrmined. The average levels of temperature, pH and salinity were 23 °C, 7.9 and 4.1 g/l, respectively. The average levels were 5.7 and 197 mg O2/l for DO and COD during the period of study. Ammonia, nitrite, nitrate and total phosphorus average levels were 1.5, 0.65, 1.1 mg N/l and 0.5 mg P/l, respectively.
Bacteriological examinations were determined in water and fish from Qaroun lake and El-Manzala lake. Total and fecal coliforms were determined in water and fish collected from two lakes. The average MPN-index/100ml of total and fecal coliforms recorded in water were 4.7 x 105,3.1 x 104 in Qaroun lake and 1.3 x 105, 1.7 x 103 in El-Manzala lake, respectively.
Whereas the average values of total and fecal coliforms of tilapia fish collected from Qaroun lake were 3.2 x 103, 3.0 x 103 in liver and 4.3 x 104, 3.9 x 103 MPN- index/ g in gills, respectively. It has been noticed from the result that total coliforms detected two times while, fecal coliforms detected only one time in muscle during all seasons. The average MPN-index/g of total and fecal coliforms in mullet fish collected from Qaroun lake were 2.4 x 103, 2.1 x 103 in liver and 4.3 x 104, 4.3 x 104 MPN- index/ g in gills, respectively. Results have been shown that total and fecal coliforms detected two times only in muscle during the period of study. On the other hand, The average values of total and fecal coliforms of tilapia fish collected from El-Manzala lake were 2.8 x 103, 2.1 x 103 in liver and 2.8 x 104, 3.8 x 103 MPN- index/ g in gills, respectively. The average MPN-index/g of total and fecal coliforms in mullet fish collected from El-Manzala lake was 2.8 x 103, 2.5 x 102 in liver and 3.4 x 104, 5.6 x 103 MPN- index/ g in gills, respectively. Results have shown that total and fecal coliforms not detected in muscle of tilapia and mullet during all seasons.
Aeromonads group was determined by surface plate technique in water and fish collected from two lakes during 12 months (November 2015- October 2016). The average CFU/100ml of A. hydrophila was 1.2 x 103 and 1.8 x 103 in Qaroun lake and El-Manzala lake, respectively. While the average counts of other Aeromonas spp. were 1.9 x 103 and 2.7 x 103 CFU/100ml in two lakes, respectively.
Aeromonads were determined in fish (muscle, liver and gills) collected from two lakes. In Qaroun lake tilapia fish the average A. hydrophila values of CFU/g in muscle, liver and gills were 3.2 x 102, 3.5 x 104 and 2.7 x 104, respectively. Whereas, in mullet fish the average values of A. hydrophila were 2.8 x 102, 1.6 x 103 and 3.1 x 105 CFU/g in three organs, respectively. Alternatively, the average values of A. hydrophila in tilapia fish collected from El-Manzala lake were 7.2 x 104 and 1.2 x 106 CFU/g in liver and gills, respectively. While, in mullet fish the average values of A. hydrophila were 2.5 x 105 and 1.0 x 106 CFU/g in two organs, respectively. Results have shown that Aeromonads not detected in muscle during all seasons.
Results indicated that 421 isolates of total Aeromonads were isolated from water and fish collected from two lakes using surface plate technique. After confirmation by PCR; it was found that 310 isolates were A. hydrophila.
Staphylococcus aureus were determined by surface plate technique in water and fish collected from Qaroun lake and El-Manzala lake during 12 months (November 2015- October 2016). The average CFU/100 ml of S. aureus recorded in water was 3.4 x 103 and 3.4 x 103 in two lakes, respectively. Furthermore, S. aureus were determined in fish organs (muscle, liver and gills). In tilapia fish from Qaroun lake; the average values of MPN-index/g were: 2.0×103 in liver and 3.5×104 in gills CFU /g. The count of S. aureus was recorded only two times during the study period in muscle organs. While in mullet fish collected from Qaroun lake the average values were: 1.5×103 in liver and 3.0×104 in gills CFU / g. It has been recorded three times during the four seasons in muscle samples. In tilapia fish from El-Manzala lake the average values were: 2.5 x 103 and 4.3 x 104 CFU/g in liver and gills, respectively. On the other hand, in mullet fish from El-Manzala lake the average values were: 4.2 x 103 and 6.3 x 104 CFU/g in liver and gills, respectively. It has been detected in muscle of both tilapia and mullet fish.
Staphylococcus aureus were determined in fish and water collected from two lakes by surface plate technique and confirmed by PCR techniques. 267 isolates were S. aureus +ve when tested by PCR from which only 214 isolates were +ve .
Pseudomonas aeruginosa were determined in water collected from two lakes. The average values of P. aeruginosa (MPN-index/100ml) recorded in water was 1.5 x 103 and 1.4 x 103 in Qaroun lake and El-Manzala lake, respectively. Moreover, P. aeruginosa were determined in fish collected from Qaroun lake in 3 organs; muscle, liver and gills. The average values in tilapia fish were: 5.0 x 102 and 3.7 x 103 MPN- index/g in liver and gills, respectively. While, it was detected only one time in muscle. Furthermore, the average values in mullet fish were: 2.5 × 103 and 4.7 × 103 MPN- index/g in the liver and gills; respectively. While, P. aeruginosa was detected in muscle of mullet fish three times only during the period of study. In case of El-Manzala lake, the average values were: 1.7 x 102 and 4.0 x 103 MPN- index/g in liver and gills, respectively. from the result we can notice that P. aeruginosa not detected in muscle during the all seasons. Also, the average values were: 5.0 × 102 and 9.0 × 103 MPN-index/g in liver and gills; respectively. While, P. aeruginosa was not detected in muscle of mullet fish during the period of study.
It was found that 243 P. aeruginosa were isolated from water and fish in two lakes using MPN method from which 243 isolates were +ve P. aeruginosa when tested by PCR.
The results of antibacterial activity showed that the synthesized nanoparticles (Ag and ZnO) inhibited A. hydrophila, S. aureus and P. aeruginosa. More synergistic effect was observed when both AgNPs and ZnONPs combined with antibiotics.
Expression of two stress related genes in fish were evaluated during this study. The results indicated that the highest percentage of heat shock protein (HSP90) and metallothionein (MT) gene expression were found in fish collected from Qaroun lake followed by El-Manzala lake which may be attributed stress factors such as temperature, salinity and heavy metals.
In case of micronucleus assay (MN) in fish, the results revealed that MN means were less in El-Manzala lake fish (tilapia and mullet) than those collected from Qaroun lake fish.