Antimicrobial Activities of Marine Sponge-Associated Bacteria

Abstract

The misuse and overuse of antibiotics have led to the emergence of multidrug-resistant microorganisms, which decreases the chance of treating those infected with existing antibiotics. This resistance calls for the search of new antimicrobials from prolific producers of novel natural products including marine sponges. Many of the novel active compounds reported from sponges have originated from their microbial symbionts. Therefore, this study aims to screen for bioactive metabolites from bacteria isolated from sponges. Twelve sponge samples were collected from South Australian marine environments and grown on seven isolation media under four incubation conditions; a total of 1234 bacterial isolates were obtained. Of these, 169 bacteria were tested in media optimized for production of antimicrobial metabolites and screened against eleven human pathogens. Seventy bacteria were found to be active against at least one test bacterial or fungal pathogen, while 37% of the tested bacteria showed activity against Staphylococcus aureus including methicillin-resistant strains and antifungal activity was produced by 21% the isolates. A potential novel active compound was purified possessing inhibitory activity against S. aureus. Using 16S rRNA, the strain was identified as Streptomyces sp. Our study highlights that the marine sponges of South Australia are a rich source of abundant and diverse bacteria producing metabolites with antimicrobial activities against human pathogenic bacteria and fungi.

Factors affecting the isolation and diversity of marine sponge-associated bacteria

“…Our findings predict that marine sponges will continue to be a good source of novel antimicrobials (Anteneh et al 2021 ). This is especially the case when similarity analysis of these bacteria with type strains showed about 30% could potentially be new species, as has been found in other studies (Abdelmohsen et al 2010 ; Afonso de Menezes et al 2017 ; Ahn et al 2011 ).…”

“…South Australian marine environments are a source of many sponge species with approximately 60% of them being endemic (Sorokin and Currie 2008 ). Variations in the chemical composition among sponges in South Australia have been reported (Sorokin et al 2007 ; Sorokin and Currie 2008 ), and it is expected that the associated bacteria could also be different either in terms of diversity or in the type of metabolites they produce (Anteneh et al 2021 ). Therefore, this study was designed to isolate bacteria from marine sponges, investigate factors affecting their relative diversity, and compare the diversity with a culture-independent approach.…”

Impact of growth media and pressure on the diversity and antimicrobial activity of isolates from two species of hexactinellid sponge

“…Previous reports of antimicrobial screening vary with respect to sample and methodology. Previous studies from sponges have reported hit rates of 8.4-41% without dereplication strategies [46][47][48]. Previous studies in soil and wastewater have reported hit rates of 1.3-42.4% [49,50].…”

Acremopeptaibols A–F, 16-Residue Peptaibols from the Sponge-Derived Acremonium sp. IMB18-086 Cultivated with Heat-Killed Pseudomonas aeruginosa

“…Microorganisms surviving in such antagonistic environments are likely to have unique metabolism and produce a variety of bioactive metabolites to suppress potential competitors. 4 Numerous studies have revealed that many antimicrobial compounds isolated from sponges are of spongeassociated microbial origin. 5 Thus, sponge-associated microorganisms, particularly bacteria and fungi, are regarded as a prospective source of novel antibiotics.…”

“…5 Thus, sponge-associated microorganisms, particularly bacteria and fungi, are regarded as a prospective source of novel antibiotics. 4,5 It is well known that many biosynthetic gene clusters in microorganisms remain silent under standard laboratory conditions. 6 Co-culturing different microbes in a single environment is an effective approach to enhance the chemical diversity of metabolites.…”