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Screening of
Vibrio sp
., a Potential Pathogen in Marketed Sea Foods
3
overnight Amikacin (Ak, 30 μg), Ampicillin (Amp, 10 μg),
Amoxyclave (Amc, 30 μg), Aztreonam (At, 30 μg),
Ceftazidime (Ca, 30 μg), Cefotaxime (Ctx, 30 μg),
Ciprofloxacin (Cf, 5 μg), Co-trimoxazole (cot, 25 μg),
Erythromycin (E, 15 μg), Gentamycin (Gen, 10 μg),
Imipenem (Ipm, 10 μg), Levofloxacin (Le, 5 μg),
Methicillin (M, 10 μg), Nalidixic acid (Na, 30 μg),
Netillin (Nt, 30 μg), Nitrofurantoin (Nf, 300 μg),
Novobiocin (Nv, 5 μg), Tobramycin (Tob, 10 μg),
Tetracyclin (T, 30 μg), Vancomycin (Va, 30 μg). After
incubation, the diameter of the zone of inhibition,
were measured in mm and compared with zone diameter
interpretative chart to determine the sensitivity of the
isolates to the antibiotics (Hi media, laboratory).
1.6 Effect of pH on Bacterial Growth
All the bacteria were inoculated into Nutrient broth
containing different pH ranges (6, 7, 8, 9, 10) and
incubated a 37
℃
. After incubation, the optical density
was measured at 600 nm.
1.7 Effect of Temperature on Bacterial Growth
Bacterial isolates were inoculated into Nutrient broth
(NB) broth and the tubes were incubated at different
temperature range (20, 30, 40, 50 and 60
℃
) for 24
hours. After incubation, the optical density was
measured at 600 nm.
1.8 Effect of Salinity on Bacterial Growth
All the bacterial isolates were inoculated into Nutrient
broth preferred with different salinity ranges such as 5,
10, 15, 20, and 25% and incubated at 37
℃
. After
incubation, the optical density was measured at 600 nm.
1.9 Effect of carbon and nitrogen sources on
bacterial growth
All the bacterial strains were inoculated into
Nutrient broth (NB) broth containing different
carbon sources (Glucose, Sucrose, Lactose) and
incubated 37
℃
. After incubation, the optical density
was measured at 600 nm.
1.10 Effect of mineral sources on bacterial growth
All the bacterial strains were inoculated into Nutrient
broth (NB) broth containing different mineral sources
(Magnesium sulphate, Calcium chloride and Zinc
sulphate) and incubated at 37
℃
. After incubation, the
optical density was measured.
1.11 Isolation of plasmid DNA by rapid method
(Kalaichelvan
，
2005)
The plasmid DNA was retrived using the following
protocol as depicted by kalaiselven (2005).
2 Results
The prevalence and distribution of Vibrios were
analyzed in marketed sea foods sample from Tuticorin
and Thirunelveli market. Their antibiotic resistant
pattern and molecular weight of the randomly selected
Vibrio sp
. were detected. In this work around 36
Vibrio sp
., were isolated and identified through the
biochemical tests were observed.
The amino acids (Arginine, Lysine, Ornithine)
decarboxylase test were carried out in aerobic and
anaerobic conditions to know the requirement of
amino acids by the isolates and the results are
tabulated in Table 1. Most of the isolates were positive
to Lysine and ornithine, but exhibited negative result
to Arginine. Sugar fermentation (Sucrose and Lactose)
tests were carried out which showed most of the
isolates to be negative to both the sugars and few were
positive results.
The isolates were subjected salt tolerance character that
was analyzed at different % of NaCl (1, 3, 6, 8, and 10).
Apart from
Vibrio cholerae
other
Vibrio
sp could not
grown in 0% NaCl, whereas all the isolates grew in 1%
NaCl.
V. alginolyticus
alone grew at 10% NaCl.
Table 1 Decarboxylase testing for
Vibrio
sp. Isolated from marketed sea foods sample
S.NO
Decarboxylase test
Oxidative
1
2
3
4
5
6
7
8
9
10
11
12
1
Arginine
-
-
-
-
-
-
-
-
-
-
-
-
2
Ornithine
+
+
+
+
-
+
+
+
+
+
+
+
3
Lysine
+
+
+
+
+
+
+
+
+
+
+
+
Note: (+) – Positive, (
-
) – Negative, 1
-
V. parahaemolyticus
, 2
-
V. parahaemolyticus
, 3
-
V.vulnificus
, 4
-
V. cholerae
, 5
-
V. alginolyticus
, 6
-
V.
parahaemolyticus
, 7
-
V. parahaemolyticus
,8
-
V. cholerae
, 9
-
V. Parahaemolyticus
, 10
-
V.mimicus
, 11
-
V. vulnificus
,12
-
V parahaemolyticus