Characterization and Antimicrobial Potential of Marine Actinomycetes From Estuaries of Uttara Kannada District, Karnataka

Abstract

The oceans cover about 70% of the Earth's surface and harbor most of the planets biodiversity. The marine environment has become a prime resource in search and discovery for novel natural products and biological diversity and marine actinomycetes turn out to be important contributors. The diversity of marine actinomycetes is enormous and has immense scope for the discovery of novel bioactive metabolites. The present study describes the antimicrobial potential of crude extracts of marine Actinomycetes species isolated from Aghanashini, Sharavathi and Kali estuaries of Uttara Kannada district, Karnataka, India. The sediment and water samples were collected from different sites of estuaries and subjected for serial dilution and plating. A total of 43 actinomycetes isolates were obtained on Starch Casein Nitrate Agar and Kusters Agar supplemented with 10% sea water. The isolates were identified as Actinomycetes by morphological and biochemical studies. The results revealed diversity of Actinomycetes with varying spore, aerial and substrate mycelium colours such as white, grey, pink, yellow and black. The colonies formed were discrete, powdery, raised and velvety colonies with brown, yellow and maroon pigmentations. The spore chain morphology studies showed different arrangements like rectus, flexibilis, retinaculum aperatum -open loops, hooks and spira -simple spirals. Primary screening for antimicrobial activity was determined by cross streak method against 16 bacterial isolates among which 07 isolates were gram positive and 09 isolates were gram negative, 02 yeasts viz., Candida albicans and Cryptococcus neoformans and a dermatophyte Trichosporon. The actinomycetes isolates from marine environments have shown to be potent in inhibiting the test bacteria and fungi. Further studies on cytotoxic potential of the actinomycetes isolates on cell lines are under progress.

Ação antimicrobiana de actinomicetos rizosféricos de guaranazeiro

“…Apesar do pequeno número amostral de isolados investigados, esses resultados mostram que esses micro-organismos são fontes importantes de metabólitos secundários, e vão de encontro aos resultados já descritos na literatura como o de Mohamed et al (2017) que isolou 32 actinomicetos do solo do Saara, e 13 mostraram atividade antibacteriana pelo mesmo método acima citado, e os isolados C, MS1 e 10 apresentaram amplo espectro tanto com bactérias gram-positivas quanto com gram-negativas, mais especialmente contra Micrococcus luteus, S. aureus e Staphylococcus epidermidis. Mesta et al (2017) Esses resultados demonstram que apesar desses organismos apresentarem um excelente potencial de produção de metabólitos secundários extracelulares, poucos são os isolados que possuem ação antimicrobiana, e que podem ter atividade antibiótica sendo capazes de inibirem os organismos ora testados.…”

Diversity and Biotechnological Potential of Marine Actinomycetes from India

“…These isolates were most used against different human and fish pathogens [ 17 ]. Similarly, Mesta and Onkarappa successfully obtained 43 isolates from Aghanashini, Sharavathi, and Kali estuaries, Karnataka which was able to successfully inhibit various pathogenic bacteria and fungi [ 18 ]. The isolates obtained from different estuary samples from all over the country were mostly noted for anti-microbial properties.…”

Genus Pseudonocardia : What we know about its biological properties, abilities and current application in biotechnology

“…The anti‐bacterial activity of the Actinobacteria, including Pseudonocardia , has been evaluated by methods, including disc diffusion (Low et al, 2015), overlay agar technique and agar well diffusion against pathogenic micro‐organisms (Parmar et al, 2016), conventional spot inoculation (Shumaila et al, 2015) and single line streak method (Mesta & Onkarappa, 2017) on agar medium. There are various protocols for performing the disc diffusion method.…”