Evaluation of toxicity and resistant effects of heavy metals and antibiotics on the growth of marine bioluminescent bacteria

Abstract

Luminescence is the emission of light by an object. Living organisms including certain bacteria are capable of luminescence. Bacteria are the most abundant luminescent organisms in nature. Bacterial luminescence has been studied most extensively in several marine bacteria. Bacterial luminescence is due to the action of the enzyme called luciferase. The luminescent bacteria exist in nature either as free-living bacteria or in symbiotic association with certain marine organisms. Research on luminescent bacteria has always been a fascinating one. In the present study, ten free living luminescent bacteria initially isolated from marine origin were characterized for their tolerance to heavy metals and antibiotics. Copper, zinc, cobalt and cadmium metals at 1 mg/mL concentration have inhibited the growth and luminescence of the all strains except strains 1, 2 and 7. Surprisingly, lead metal at the same concentration dd not inhibit any of the ten strains. However, at 2 mg/mL concentration, similar trend was observed on the growth and luminescence of all the 10 strains. Also, all the tested isolates were sensitive (1 cm >) to all Gram negative and positive antibiotics being tested except isolates 3, 6 and 8, respectively which were resistant (0 – 0.9 cm) to all the antibiotics tested. Thus, the strains isolated from the different sample types have good beneficial potentials such as heavy metal tolerance and antibiotic sensitivity.