International Journal of Marine Science, 2017, Vol.7, No.14, 125-129
126
83°20’28.23”E) of Visakhapatnam coast, Andhra Pradesh. The samples were collected and brought to the
laboratory immediately and cleaned with water to remove sand and other dust particles, if any. The shells were
broken with the help of scalps and small hammer and the meat is collected in a clean container. The entire meat
collected was divided into two equal parts for extracting by both dry and wet methods.
Figure 1
Cellana radiate
dorsal and ventral views
1.1 Wet method
The whole animal is removed and cut into small pieces and ground in a pestle-mortar until the mixer becomes as
homogenous mass. The whole content was soaked in 1:5 ratio (w/v) of methanol: chloroform (9:1) and ethyl
acetate: chloroform (9:1) for 72 hours (Sunil et al., 2016). After soaking the samples were concentrated to 100
mg/ml in methanol and ethyl acetate by rota-evaporator.
1.2 Dry method
The known amount of meat was kept in hot air oven at 55
°
C for 72 hours. The dried samples were powdered and
dissolved in 1:5 ratio (w/v) of methanol: chloroform (9:1) and ethyl acetate: chloroform (9:1) for 72 hours (Sunil
et al., 2016). After soaking the samples they were concentrated to 100 mg/ml in methanol and ethyl acetate.
1.3 Preparation of microbial cultures
Three pathogens namely,
Escherichia coli, Staphylococcus aureus, Vibrio harveyi
were selected to know the
antagonistic activity. 2.5 gms of nutrient broth (HIMEDIA) was dissolved in 100 ml of distilled water and
autoclaved at 121°C, 15 lbs. for 15 min. The broth was cooled down to room temperature and bacterial cultures
were inoculated in sterilized nutrient broth and were incubated at 37°C for 24 hrs.
1.4 Antagonistic activity
The extracts were tested for their anti-bacterial activity by agar well diffusion method (Perez et al., 1990). The 18
hrs. young culture broths were taken and the pathogenic strains were spread evenly over sterile Mueller Hinton
Agar plates. The 6 mm diameter wells were prepared on agar plates by using sterile cork borer. The wells were
filled with 100 µL extract and controls were arranged. The plates were incubated at 37°C for 24 hours.
Antibacterial activities were evaluated by measuring the zone of inhibition showed in millimeters (mm).
2 Results
The two different extracts of
Cellana radiata
were screened for their antibacterial activity against three different
pathogenic bacteria. The methanolic dry extracts did not show any inhibitory zones but the wet extracts have
shown antibacterial activity against
Vibrio harveyi
(Figure 2; Figure 3; Table 1). The ethyl acetate extracts (from
both wet and dry methods) have shown inhibitory zones against
Vibrio harveyi
(Figure 2; Figure 3; Table 1).
