318
16.1 Introduction
Coral reefs are the most diverse and valuable of all marine ecosystems on earth.
This ecosystem is often called the rainforests of the sea due to the diversity it harbors (Connell 1978). It supports more species per unit area than any other marine
ecosystem. According to a recent survey, it harbors approximately 4000 species of
fish, 800 species of hard corals, and hundreds of other species. Scientists have estimated that there may be another one to eight million undiscovered species of living
organisms in the reef ecosystem (Reaka-Kudla 1997). The estimated total net benefit per year from the reef ecosystem of the world is $29.8 billion mainly derived
from the ecosystem services such as tourism and recreation, coastal protection,
fisheries, and biodiversity (Brooke and Ross 2014) (Fig. 16.1). In recent years, it has
also become a valuable resource for the modern drug discovery (Rosenberg and
Falkovitz 2004). Therefore, there is an increasing interest in the field of coral ecology in the last few decades, mainly driven by the desire to harvest the benefits that
it provide to the human and its neighboring community. However, for the productivity and sustainability of reef ecosystem, healthy corals are crucial, but in this day
and age, they are on the verge of degradation due to various anthropogenic activities
such as blast fishing and coastal water pollution (Faden 2008). These activities alter
Contents
16.1 Introduction .................................................................................................................... 318
16.2 Coral and Its Structure ................................................................................................... 320
16.3 Bacterial Diversity Associated with Coral Reef Ecosystem .......................................... 321
16.4 Role of Coral-Associated Bacteria ................................................................................. 323
16.4.1 Coral-Associated Bacteria as a Companion of Coral Holobiont ...................... 323
16.4.1.1 Bacteria as a Key Nutrient Supplier ................................................. 324
16.4.1.2 Bacteria Required for Metamorphosis and Settlement
of Coral Larva .................................................................................. 325
16.4.1.3 Coral-Associated Bacteria Contribute to Host Defense
Against Unwanted Colonization and Biofouling ............................. 326
16.4.2 Coral-Associated Bacteria as a Pathogen ......................................................... 327
16.5 Recent Technologies to Study the Role of Bacteria in Coral Ecosystem ...................... 327
16.5.1 PCR-Based Methods ........................................................................................ 328
16.5.1.1 Denaturing Gradient Gel Electrophoresis (DGGE) ......................... 330
16.5.1.2 Quantitative Real-Time PCR (qRT-PCR) ........................................ 330
16.5.2 Nucleic Acid Hybridization-Based Techniques ................................................ 331
16.5.2.1 Fluorescent In Situ Hybridization (FISH) ........................................ 331
16.5.2.2 Microarray ........................................................................................ 333
16.5.2.3 Membrane-Based Methods .............................................................. 333
16.5.3 Western Blot: A Protein-Based Molecular Technique ...................................... 335
16.5.4 Next-Generation Tools...................................................................................... 336
16.5.5 Omics Tools ...................................................................................................... 336
16.5.5.1 Metaproteomics ................................................................................ 336
16.5.5.2 Metabolomics ................................................................................... 337
References ................................................................................................................................. 337
N.P. Patel et al.
16.1 Introduction
Coral reefs are the most diverse and valuable of all marine ecosystems on earth.
This ecosystem is often called the rainforests of the sea due to the diversity it harbors (Connell 1978). It supports more species per unit area than any other marine
ecosystem. According to a recent survey, it harbors approximately 4000 species of
fish, 800 species of hard corals, and hundreds of other species. Scientists have estimated that there may be another one to eight million undiscovered species of living
organisms in the reef ecosystem (Reaka-Kudla 1997). The estimated total net benefit per year from the reef ecosystem of the world is $29.8 billion mainly derived
from the ecosystem services such as tourism and recreation, coastal protection,
fisheries, and biodiversity (Brooke and Ross 2014) (Fig. 16.1). In recent years, it has
also become a valuable resource for the modern drug discovery (Rosenberg and
Falkovitz 2004). Therefore, there is an increasing interest in the field of coral ecology in the last few decades, mainly driven by the desire to harvest the benefits that
it provide to the human and its neighboring community. However, for the productivity and sustainability of reef ecosystem, healthy corals are crucial, but in this day
and age, they are on the verge of degradation due to various anthropogenic activities
such as blast fishing and coastal water pollution (Faden 2008). These activities alter
Contents
16.1 Introduction .................................................................................................................... 318
16.2 Coral and Its Structure ................................................................................................... 320
16.3 Bacterial Diversity Associated with Coral Reef Ecosystem .......................................... 321
16.4 Role of Coral-Associated Bacteria ................................................................................. 323
16.4.1 Coral-Associated Bacteria as a Companion of Coral Holobiont ...................... 323
16.4.1.1 Bacteria as a Key Nutrient Supplier ................................................. 324
16.4.1.2 Bacteria Required for Metamorphosis and Settlement
of Coral Larva .................................................................................. 325
16.4.1.3 Coral-Associated Bacteria Contribute to Host Defense
Against Unwanted Colonization and Biofouling ............................. 326
16.4.2 Coral-Associated Bacteria as a Pathogen ......................................................... 327
16.5 Recent Technologies to Study the Role of Bacteria in Coral Ecosystem ...................... 327
16.5.1 PCR-Based Methods ........................................................................................ 328
16.5.1.1 Denaturing Gradient Gel Electrophoresis (DGGE) ......................... 330
16.5.1.2 Quantitative Real-Time PCR (qRT-PCR) ........................................ 330
16.5.2 Nucleic Acid Hybridization-Based Techniques ................................................ 331
16.5.2.1 Fluorescent In Situ Hybridization (FISH) ........................................ 331
16.5.2.2 Microarray ........................................................................................ 333
16.5.2.3 Membrane-Based Methods .............................................................. 333
16.5.3 Western Blot: A Protein-Based Molecular Technique ...................................... 335
16.5.4 Next-Generation Tools...................................................................................... 336
16.5.5 Omics Tools ...................................................................................................... 336
16.5.5.1 Metaproteomics ................................................................................ 336
16.5.5.2 Metabolomics ................................................................................... 337
References ................................................................................................................................. 337
N.P. Patel et al.