Sponge-Associated Bacteria Produce Non-cytotoxic Melanin Which Protects Animal Cells from Photo-Toxicity.
Melanin is a photo-protective polymer found in many organisms. Our research shows that the bacteria associated with darkly pigmented sponges (Haliclona pigmentifera, Sigmadocia pumila, Fasciospongia cavernosa, Spongia officinalis, and Callyspongia diffusa) secrete non-cytotoxic melanin, with antioxidant activity that protects animal cells from photo-toxicity. Out of 156 bacterial strains screened, 22 produced melanin and these melanin-producing bacteria (MPB) were identified as Vibrio spp., Providencia sp., Bacillus sp., Shewanella sp., Staphylococcus sp., Planococcus sp., Salinococcus sp., and Glutamicibacter sp. Maximum melanin production was exhibited by Vibrio alginolyticus Marine Microbial Reference Facility (MMRF) 534 (50 mg ml-1), followed by two isolates of Vibrio harveyi MMRF 535 (40 mg ml-1) and MMRF 546 (30 mg ml-1). Using pathway inhibition assay and FT-IR spectral analysis, we identified the melanin secreted into the culture medium of MPB as 1,8-dihydroxynaphthalene-melanin. The bacterial melanin was non-cytotoxic to mouse fibroblast L929 cells and brine shrimps up to a concentration of 200 and 500 ppm, respectively. Bacterial melanin showed antioxidant activity at very low concentration (IC50-9.0 ppm) and at 50 ppm, melanin protected L929 cells from UV-induced intracellular reactive oxygen stress. Our study proposes sponge-associated bacteria as a potential source of non-cytotoxic melanin with antioxidant potentials.
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Vijitha
V
Vijayan
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Chekidhenkuzhiyil
C
Jasmin
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India. anas@nio.org.
Abdulaziz
A
Anas
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Sreelakshmi
S
Parakkaparambil Kuttan
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Saradavey
S
Vinothkumar
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Parameswaran
P
Perunninakulath Subrayan
CSIR-National Institute of Oceanography (NIO), Regional Centre Cochin, Dr. Salim Ali Road, Cochin, Kerala, 682018, India.
Shanta
S
Nair
D000818:Animals; D001419:Bacteria / Q000737:chemistry / Q000254:growth & development / Q000302:isolation & purification; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D008543:Melanins / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D011161:Porifera / Q000382:microbiology*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D008543:Melanins
Antioxidant; Melanin; Photo-toxicity; Sponge-associated bacteria; UV stress