Survey study was carried out throughout four seasons from four locations
representing the whole protected area "Ashtoum El-Gamil", Port Said governorate,
Manzala Lake concerning the bacterial load in water and fish of this park. The
bacterial load in water samples increased by increasing water temperature, the range
of total count of bacteria was 0.6×106 to 0.2×108 /100 ml of water sample in winter
and summer respectively. The following bacterial genera were isolated from water
samples: Aeromonas, Bacillus, Proteus, Pseudomonas, Streptococcus, S. epidermidis,
S. aureus, Micrococcus, Vibrio and E. coli. The predominant microorganisms isolated
from water were E. coli, Bacillus spp., Vibrio spp. and Pseudomonas spp. While the
total bacterial counts (TBCs) from fish samples obtained on NA media were higher in
summer season in all tested organs than other seasons (spring, winter and autumn);
also, the high bacterial load was observed in both of gills and intestine comparing
with the liver. TBCs were 0.8×107, 0.52×107 and 0.13×107 cfu / g in gills, intestine
and liver, respectively in location No. 3 (bahr kassab) during the summer. The highest
TBCs obtained on McCA, MSA, and BHA media were 0.16×107, 0.25×107, and
0.3×107 cfu / g of gills in locations No. 1, 1 and 3 during summer, autumn and
summer, respectively. The bacterial species isolated also from fish were namely V.
cholerae, V. parahaemolyticus, Aeromonas spp., E. coli, Yersinia spp., Proteus,
Pseudomonas spp., Micrococcus spp., S. epidermidis, S. aureus and Streptococcus
spp. In the pathogenicity test, the most pathogenic bacteria for tilapia fish were
Pseudomonas spp., V. cholerae and Aeromonas spp which causing greater than 70,
60% and 60% mortality within 96 hr respectively.