Diversity and antimicrobial activity of bacteria isolated from different Brazilian coral species

Abstract

Corals harbor a wide diversity of bacteria associated with their mucus. These bacteria can play an important role in nutrient cycling, degradation of xenobiotics and defense against pathogens by producing antimicrobial compounds. However, the diversity of the cultivable heterotrophic bacteria, especially in the Brazilian coral species, remains poorly understood. The present work compares the diversity of cultivable bacteria isolated from the mucus and surrounding environments of four coral species present along the Brazilian coast, and explores the antibacterial activity of these bacteria. Bacteria belonging to the phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were isolated. The mucus environment presented a significantly different bacteria composition, compared to the water and sediment environments, with high abundance of Alcanivorax, Acinetobacter, Aurantimonas and Erythrobacter. No difference in the inhibition activity was found between the isolates from mucus and from the surrounding environment. Eighty-three per cent of the bacteria isolated from the mucus presented antimicrobial activity against Serratia marcescens, an opportunistic coral pathogen, suggesting that they might play a role in maintaining the health of the host. Most of the bacteria isolates that presented positive antimicrobial activity belonged to the genus Bacillus.

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“…For instance, a soft coral, Alcyonium digitatum contains Firmicutes, Actinobacteria, Gamma proteobacteria, and Alphaproteo bacteria 9 . Bacterial communities in most corals may be involved in nutrient cycling, degradation of xenobiotic, and defense against pathogens by antimicrobial compound production or coral health and survival 10,11 . The bacterial communities can be abundant on the compartments of corals such as mucus layer, tissue, and skeletons and each compartment contains the different bacterial group 12 .…”

“…The high diversity of bacteria among coral compartments induces competition among them or between bacteria and coral to produce secondary metabolites, for example, antimicrobial compounds 10 . The antimicrobial compounds can be used to protect the coral against the infection from coral pathogenic bacteria such as Vibrio sp.…”

“…Secondary metabolites of Bacillus also shows various biological activities, such as antiviral, antimicrobial, anticancer, etc. 17 Most bacteria associated with soft corals shows antimicrobial activities 9,10 . Bacillus sp.…”

“…Bacillus sp. associated with Brazillian coral species show 23.6% of antimicrobial activity 10 . Cereusit in the A produced by Bacillus cereus strain isolated from the soft coral Antillogorgia (syn.…”

Outlook of fosmid library from metagenomic of the symbionts associated with coral Siderastrea stellata: structural and functional screening for metabolic and antimicrobial activity

“…Clone P07H3 also exhibited antimicrobial activity against all the test strains, demonstrating inhibitory potential against S. aureus, S. Enterica PT4, S. Enterica PT11 and S. Typhi (Figure 3). Antimicrobial activity is well documented in Cnidaria, especially soft corals (Koh, 1997;Mariottini et al, 2016;Pereira et al, 2017). Others prospecting using corals samples also demonstrated the inhibitory action of defensive agents against S. aureus (ElAhwany et al, 2015;Qin et al, 2015), S. Enterica (Correa et al, 2011).…”