Ecological and biotechnological importance of secondary metabolites produced by coral‐associated bacteria

Abstract

Summary Symbiotic relationships between corals and their associated micro‐organisms are essential to maintain host homeostasis. Coral‐associated bacteria (CAB) can have different beneficial roles in the coral metaorganism, such as metabolizing essential nutrients for the coral host and protecting the coral from pathogens. Many CAB exert these functions via secondary metabolites, which include antibacterial, antifouling, antitumour, antiparasitic and antiviral compounds. This review describes how analysis of CAB has led to the discovery of secondary metabolites with potential biotechnological applications. The most commonly found types of secondary metabolites, antimicrobial and antibiofilm compounds, are emphasized and described. Recently developed methods that can be applied to enhance the culturing of CAB from shallow‐water reefs and the less‐studied deep‐sea coral reefs are also discussed. Last, we suggest how the combined use of meta‐omics and innovative growth‐diffusion techniques can vastly improve the discovery of novel compounds in coral environments.

Insights into the Cultured Bacterial Fraction of Corals

“…We end by highlighting the importance and need for a global initiative to create an online catalog of genomic and physiological features of cultured coral-associated bacteria. Combining the use of these genomic insights with innovative culturing techniques ( 37 ), aimed at improving the collection of coral-associated bacterial isolates, will see this field of coral biology move forward. Such an initiative should likely start with those microbes which have their complete genomes sequenced.…”

“…Organismal, growth form, and tissue complexity create unique microenvironments that are thought to contribute to the high bacterial diversity often seen in corals ( 32 – 34 ). The diverse coral bacteriome plays an integral role in the balance between health and disease of the coral holobiont ( 35 , 36 ) and represents a valuable source of biotechnological products ( 37 , 38 ). Disalvo ( 39 ) was perhaps the first to isolate bacteria from coral in 1969, recovering strains from the skeletal regions of Porites lobata , followed by Ducklow and Mitchell ( 40 ) who reported on bacteria isolated from mucus of Porites astreoides and two octocoral species 10 years later.…”

Insights into the cultured bacterial fraction of corals

“…Tissue compartmentalization and organismal complexity are thought to underlie high bacterial diversity in corals 26,27,28 . The diverse coral bacteriome plays an integral role in the balance between health and disease of the coral holobiont 29 and represents a valuable source of biotechnological products 30 . 31 was perhaps the first to actively isolate bacteria from coral, recovering strains from the skeletal regions of Porites lobata followed by 32 who reported on bacteria isolated from mucus of Porites astreoides and two soft coral species.…”

Exploring the Diversity and Biotechnological Potential of Cultured and Uncultured Coral-Associated Bacteria

“…Overall, these results feature the importance of polyphasic approaches in ecological and biotechnological studies. Moreover, it indicates the need for advanced techniques to cultivate micro-organisms, such as in situ, high-throughput, iChip, membrane-based diffusion, and other approaches [43,153]. These methods can enable recovery of a greater diversity and abundance of microbial isolates, which can be related to production of natural products with industrial and ecological interest [154][155][156][157].…”

“…These holobionts occupy niches that naturally select distinct microbial communities from the surrounding water [35][36][37]. Coral-associated micro-organism (CAM) assemblages are dynamic and vary according to several variables, including life stage, geographic location and environmental conditions as a means of adaptation/acclimation [38][39][40][41][42], constituting an endless source for prospecting for compounds with biotechnological potential [43,44]. As one of the most important variables selecting the CAM diversity and abundance is the species of coral host [35,45,46], different coral species should be sources of specific (and possibly new) enzymes.…”