Optimizing conditions of fluorescein isothiocyanate labeled Vibrio anguillarum and the effect of application condition on fluorescence signal

In order to track the target bacteria effectively,fluorescein isothiocyanate( FITC) was used as the marker to study the effect of labeling concentrations( 0. 2,2,20,50,100,200 μg / mL) and time( 1,15,30, 60,120,240 min) on the fluorescence intensity of V. anguillarum labeled FITC. In the meanw hile,the stability of fluorescence labeled on V. anguillarum stored at different temperatures( 25,4,- 20,- 70 ℃) and different time( 24,48,96,192 h) w ere compared. The possible change of fluorescence intensity w as monitored w hen V. anguillarum labeled FITC w as inactivated by formaldehyde. Also the fluorescence quenching effects of different intensity natural light( 0,150,1 500,25 000 lx) indoors and the effects of repeated freezing and thaw ing at- 20 and- 70 ℃ on V. anguillarum labeled FITC w ere analyzed. The results show ed that the optimal concentration of FITC w as in the range of 20 to 100 μg / mL and the optimal time w as in the range of 60 to 120 min. The fluorescent signal from V. anguillarum labeled FITC w as more stable w hen it w as stored at- 20 and- 70 ℃ than those stored at 4 and 25 ℃. The stability of fluorescent signal from formaldehyde inactivated V. anguillarum labeled FITC w as better than that from the control,and no difference w as found in the quenching effect in different intensity of natural lighting. After 3 times of freezing and thaw ing,the fluorescent signal from V. anguillarum labeled FITC frozen at- 70 ℃ w as more stable. The results above provided useful technical parameters w hen FITC w as used as a marker to label the marine bacteria.