Bioprospecting Sponge-Associated Microbes for Antimicrobial Compounds

Abstract

Sponges are the most prolific marine organisms with respect to their arsenal of bioactive compounds including antimicrobials. However, the majority of these substances are probably not produced by the sponge itself, but rather by bacteria or fungi that are associated with their host. This review for the first time provides a comprehensive overview of antimicrobial compounds that are known to be produced by sponge-associated microbes. We discuss the current state-of-the-art by grouping the bioactive compounds produced by sponge-associated microorganisms in four categories: antiviral, antibacterial, antifungal and antiprotozoal compounds. Based on in vitro activity tests, identified targets of potent antimicrobial substances derived from sponge-associated microbes include: human immunodeficiency virus 1 (HIV-1) (2-undecyl-4-quinolone, sorbicillactone A and chartarutine B); influenza A (H1N1) virus (truncateol M); nosocomial Gram positive bacteria (thiopeptide YM-266183, YM-266184, mayamycin and kocurin); Escherichia coli (sydonic acid), Chlamydia trachomatis (naphthacene glycoside SF2446A2); Plasmodium spp. (manzamine A and quinolone 1); Leishmania donovani (manzamine A and valinomycin); Trypanosoma brucei (valinomycin and staurosporine); Candida albicans and dermatophytic fungi (saadamycin, 5,7-dimethoxy-4-p-methoxylphenylcoumarin and YM-202204). Thirty-five bacterial and 12 fungal genera associated with sponges that produce antimicrobials were identified, with Streptomyces, Pseudovibrio, Bacillus, Aspergillus and Penicillium as the prominent producers of antimicrobial compounds. Furthemore culture-independent approaches to more comprehensively exploit the genetic richness of antimicrobial compound-producing pathways from sponge-associated bacteria are addressed.

Keywords: antimicrobial compounds; sponge-associated microbes; sponges.

Figure 1

Chemical structures of the antiviral compounds 2-undecyl-4-quinolone (1), sorbicillactone A (2), stachybotrin D (3), chartarutine B (4), and truncateol M (5).

Figure 2

Chemical structures of the antibacterial compounds YM-266183 (6), YM-266184 (7), kocurin (8), mayamycin (9), naphthacene glycoside SF2446A2 (10), sydonic acid (11) and trichoderin A (12).

Figure 3

Chemical structures of the antifungal compounds saadamycin (13), 5,7-dimethoxy-4-p-methoxylphenylcoumarin (14) and YM-202204 (15).

Figure 4

Chemical structures of the antiprotozoal compounds manzamine A (16), valinomycin (17), staurosporine (18) and butenolide (19).

Figure 5

Distribution of sponge-associated microorganisms found to produce antimicrobial compounds: (A) Bacteria and Fungi; (B) Bacterial genera; and (C) Fungal genera. Figure 5 was made based on the summary of the taxonomic affiliations of sponge-associated microbes (N = 272) that were found to produce antimicrobials.

Figure 6

General overview of the strategies used to discover antimicrobial compounds from sponge-associated microorganisms.