326
Thus, it suggests that TBP may have divergent impacts on net larval recruitment
that depends on the timing of larval settlement.
Bacteria are also known to guide the newly coral polyp to settle near the proximity of adult coral colonies or other coral competitors such as macro- and turf algae
(Smith et al. 2006; Marhaver et al. 2013).
Despite several studies investigating the potential role of bacteria in the induction of larval settlement and metamorphosis, a thorough understanding of all the
players involved during spawning and their mechanism is not clearly understood,
and thus it remains an important avenue for ongoing studies.
16.4.1.3 Coral-Associated Bacteria Contribute to Host Defense
Against Unwanted Colonization and Biofouling
Bacteria associated with corals guard the host from various pathogenic microorganisms. There are various mechanisms by which these bacteria provide protection to
the coral host. For instance, secondary metabolite production such as antibiotics
against opportunistic harmful bacteria on the coral surface has been reported by
various scientific studies (Mansson et al. 2011; Raina et al. 2016). A study by
Ritchie (2006) demonstrated that coral mucus has a role in structuring beneficial
coral-associated microbial communities through antibacterial activity. They may
also interrupt cell-to-cell communication among pathogens and compete with
pathogens for limiting nutrients and space on host surfaces (Shnit-Orland and
Kushmaro 2009). In addition to functioning as antimicrobials, these bacteria have
the ability to inhibit pathogen’s catabolic enzymes required by the pathogens for
establishing themselves on the host. For example, microorganisms associated with
A. palmate are found to interfere with the ability of white pox pathogen Serratia
marcescens and to use coral mucus by blocking the induction of the glycosidase
(Krediet et al. 2013).
Besides these, coral-associated bacteria have high ROS scavenging activities
such as production of antioxidant compound sand enzymes which enable them to
survive on oxidative-stressed coral surface and also protect the host and its associated microorganisms by the detrimental consequences of these radicals such as
photo-inhibition which ultimately results in coral bleaching and death (Reshef et al.
2006). Some of these antioxidants are reported to associate with virulence such as
superoxide dismutase enzyme (Munn et al. 2008; Banin et al. 2003). So, the
researchers have hypothesized that this ability of coral bacteria combined with host
property of ROS production prevents unwanted colonization of opportunistic and
pathogenic bacteria that are responsible for coral diseases.
Moreover, siderophore-producing bacteria are found on the coral surface which
suggest that these bacteria have strong biocontrol abilities against pathogenic bacteria (Solanki et al. 2014). Thus, this area required further scientific studies to establish the beneficial role of bacteria in coral health. Moreover, these inhibitory
interactions among coral-associated bacteria on the coral surface could be of
immense importance for searching secondary metabolite-producing bacteria having
pharmaceutical application.
N.P. Patel et al.
Thus, it suggests that TBP may have divergent impacts on net larval recruitment
that depends on the timing of larval settlement.
Bacteria are also known to guide the newly coral polyp to settle near the proximity of adult coral colonies or other coral competitors such as macro- and turf algae
(Smith et al. 2006; Marhaver et al. 2013).
Despite several studies investigating the potential role of bacteria in the induction of larval settlement and metamorphosis, a thorough understanding of all the
players involved during spawning and their mechanism is not clearly understood,
and thus it remains an important avenue for ongoing studies.
16.4.1.3 Coral-Associated Bacteria Contribute to Host Defense
Against Unwanted Colonization and Biofouling
Bacteria associated with corals guard the host from various pathogenic microorganisms. There are various mechanisms by which these bacteria provide protection to
the coral host. For instance, secondary metabolite production such as antibiotics
against opportunistic harmful bacteria on the coral surface has been reported by
various scientific studies (Mansson et al. 2011; Raina et al. 2016). A study by
Ritchie (2006) demonstrated that coral mucus has a role in structuring beneficial
coral-associated microbial communities through antibacterial activity. They may
also interrupt cell-to-cell communication among pathogens and compete with
pathogens for limiting nutrients and space on host surfaces (Shnit-Orland and
Kushmaro 2009). In addition to functioning as antimicrobials, these bacteria have
the ability to inhibit pathogen’s catabolic enzymes required by the pathogens for
establishing themselves on the host. For example, microorganisms associated with
A. palmate are found to interfere with the ability of white pox pathogen Serratia
marcescens and to use coral mucus by blocking the induction of the glycosidase
(Krediet et al. 2013).
Besides these, coral-associated bacteria have high ROS scavenging activities
such as production of antioxidant compound sand enzymes which enable them to
survive on oxidative-stressed coral surface and also protect the host and its associated microorganisms by the detrimental consequences of these radicals such as
photo-inhibition which ultimately results in coral bleaching and death (Reshef et al.
2006). Some of these antioxidants are reported to associate with virulence such as
superoxide dismutase enzyme (Munn et al. 2008; Banin et al. 2003). So, the
researchers have hypothesized that this ability of coral bacteria combined with host
property of ROS production prevents unwanted colonization of opportunistic and
pathogenic bacteria that are responsible for coral diseases.
Moreover, siderophore-producing bacteria are found on the coral surface which
suggest that these bacteria have strong biocontrol abilities against pathogenic bacteria (Solanki et al. 2014). Thus, this area required further scientific studies to establish the beneficial role of bacteria in coral health. Moreover, these inhibitory
interactions among coral-associated bacteria on the coral surface could be of
immense importance for searching secondary metabolite-producing bacteria having
pharmaceutical application.
N.P. Patel et al.