Land fossils are about : 450 million years old

The oldest known marine fossils are about : 3:5 billion

years

More than 40 000 different kinds of species are present in the marine environment

Marine Ecosystems

More than 80% of living organisms on earth are found in the aquatic ecosystem.

Marine environment offers a diversity

of habitats which is reflected in the

biological diversity that is found in

marine organisms.

The oceans cover 70% of the earth’s

surface

Any technological application that uses biological systems, living organisms, or derivatives thereof, to

make or modify products or processes for specific use.

Food and Agricultural Organization (FAO)

The application of scientific and engineering principles to the processing of materials by marine biological agents

provide good and services

Examples of products and services developed by technological applications using marine bioresources

Important marine sources in the research are microorganisms, algae, and sponges

It is notable that the major international effort involved 2700 researchers, about

44% from USA and Canada,

31% from Europe,

25% from the rest of the world, notably Australia, New Zealand, Japan, China, South Africa, India, Indonesia, and

Brazil

Countries and their marine biotechnology research priorities

Total number of new compounds isolated from different types of marine sources, 2001–2010

The largest structures made by living creatures

They contain an enormous diversity of organisms,

The economic value of coral reefs has been estimated to be US$375 billion per year2

(largely derived from fishing, tourism and coastal protection activities)

of two layers of cells, the epidermis and gastrodermis, covered by a surface mucus layer and connected to

a large, porous calcium carbonate skeleton

Very simple body

many materials previously isolated from

macroorganisms, such as sponges and

tunicates, are in fact, metabolic products

of associated microorganisms

The mucus layer, skeleton and tissues of healthy corals all contain large populations

of:

I. eukaryotic algae,

II. bacteria

III. and archaea.

mucus layerCorals

The role of microorganism in coral

These microorganisms confer benefits to their host by various mechanisms, including

I. photosynthesis,

II. nitrogen fixation,

III. provision of nutrients

IV. infection prevention.

The role of microorganism in coral

The apparent uniformity of the symbionts isolated from various hosts led to the assumption that all symbiotic

dinoflagellates belonged to a single species Symbiodinium microadriaticum

Molecular evidence has since demonstrated that the

genus Symbiodinium is diverse, containing multiple taxa

Each coral has its own symbiotic micro-algae

The high concentration of oxygen results in formation of oxygen radicals which provide protection against

infection

The energy requirements of their hosts by transferring photosynthetically fixed carbon to the coral

The production of large amounts of molecular oxygen that allows for efficient respiration by the coral

A pathogen of Symbiodinium in the coral

required SOD to initiate infection

Symbiodinium

Mycosporines localize to the coral mucus and are hypothesized to protect the holobiont against UV radiation and

to serve as antioxidants

Produce Mycosporines and Mycosporine-like amino acids (MAAs) :

low-molecular-weight water-soluble molecules absorbing UV radiation in the wavelength range 310-365 nm

Symbiodinium and Microbial communities

Under both stressed and non-stressed conditions supporting the hypothesis that unknown factors associated with

different Symbiodinium genotypes influence the coral microbiota composition.

Coral microbial communities have been shown to differ based on the clade of Symbiodinium present in

coral species

Healthy and bleached corals can be modeled in the laboratory by studying the Symbiodinium symbiosis.

Bacteria satisfy 50% of the total nitrogen needs of the coral

Bacteria could be crucial for the survival of the coral when it loses its endosymbiotic algae

Bacteria provide organic compounds (produced by photosynthesis) to the coral tissue

Surface mucus layer

Coral tissue (including the gastrodermal cavity)

Calcium carbonate skeleton, each of which harbour a distinct bacterial population

The coral bacterial community differs from seawater surrounding the coral suggesting the association between

the coral and its microbiota is specific

The coral probiotic hypothesis

The ability of coral to adapt to environmental stresses

temperature conditions

infection by specific pathogens

A dynamic relationship exists between symbiotic microorganisms and corals at different environmental conditions

transfer of symbionts from parent to offspring

The transmission of symbionts in corals

Vertical transmission

Horizontal transmission uptake of symbionts from the environment

Microbial associations over evolutionary time scales are likely to contribute to genome differentiation in both the host and

its associated microbial partners

If a bacterial symbiont is both vertically transmitted and an endosymbiont, its genome will be more likely to be reduced in

size relative to other bacterial that have free-living stages.

The coral-associated bacterial genomes are of a similar size as their non-coral associated relatives

For example : coral-associated genomes from Proteobacteria is similar with free-living Proteobacteria

Data on genome size reduction come from studies on insect endosymbiosis

Observation

Bacterial genome evolution in the holobiont

Environmental stress factors

Climate change,

water pollution

over-fishing

Stress resistance: the coral probiotic hypothesis

corals contain an innate immunity system,

they do not produce antibodies

lack an adaptive immunity system

Like other invertebrates, corals possess innate or natural immunity include

I. Physical barriers, such as the epidermis and mucus (the mucus surrounds the coral and is shed periodically

removing trapped microorganisms

II. Cellular components (phagocytic cells) that can engulf and destroy microorganisms on contact

III. Soluble factors, including organic acids and antimicrobial products

coral-associated bacteria inhibit pathogen invasion and actively

Innate immunity

Evidence for metabolic complementation

Association between diazotrophic bacteria and coral

Coral Acropora digitifera lacked a key enzyme that

Cysteinethione β synthase (CBS) is missing also from two other Acropora species but it has been reported in many corals

For instance

Nitrogen fixation

Oligotrophic habitat of corals Makes metabolic complementation desirable

synthesizes the essential amino acid cysteine from homocysteine or serine

Microbial interactions can play a role at each of the stages in a coral’s life cycle

Scleractinian corals reproduce

I. asexually through budding and fragmentation II. sexually by gamete spawning

How coral microbe interactions facilitate the coral life cycle

How coral microbe interactions facilitate the coral life cycle

(1) fertilization and spawning – fertilization of gametes and formation of a motile pelagic planula larva

How coral microbe interactions facilitate the coral life cycle

Mucus layer surrounding the gametes of spawning corals as media for transfer of symbionts (Symbiodinium

and bacterial species) from parent colony to larvae after gamete release

(1) fertilization and spawning

How coral microbe interactions facilitate the coral life cycle

Antimicrobial activity of resident microbes may serve a protective function for coral spawn or newly hatched larvae

(2) Settlement and metamorphosis – the selection of appropriate settlement substrate by the free-swimming planula and

metamorphosis into polyp

How coral microbe interactions facilitate the coral life cycle

Bacteria have a fundamental role in moderating metamorphosis and settlement of larvae in the marine environment

This event may be triggered by diffusible or potentially contact-mediated signals

Mechanism behind induction of coral metamorphosis by various Pseudoalteromonas strains led to isolation of the

inducing Compound tetrabromopyrrole (TBP)

Certain populations of bacteria may also deter coral settlement through diffusible signals

larvae avoid settling adjacent to benthic cyanobacteria hypothesized to produce toxic secondary metabolites

Coral colony formation

Coral must overcome competition with other benthic organisms to grow and form adult colony.

Bacteria help coral colonies versus competitors such as macro- and turf algae

High mortality (up to 100%) of coral nubbins grown with algal competitors

Antibacterial compound ampicillin rather than algal toxins, mediated the inhibitory effects

Coral colony formation

organic carbon by primary producers may enrich for heterotrophic bacteria including pathogens and opportunists

that may impact the survival of coral

How do corals influence the composition and/or functions of the associated microbiota?

To effectively structure the associated microbiota, hosts must either

(i) be able to detect specific micro-organism associated molecular patterns (MAMPs)

(ii) excrete broadly active antimicrobial compounds to select against general environmental organisms,

(iii) release chemical cues and/or nutrients attract micro-organisms with potentially beneficial functions,

(iv) attract and maintain keystone microbes which is resistant to invasions by potential pathogens

Strong evidence for scenarios (i) and (ii) would indicate that the composition of the associated microbiota is more

important,

scenarios (iii) and (iv) would argue that the function, rather than composition of the microbiota is more

consequential to the holobiont’s health and stability.

How do corals influence the composition and/or functions of the associated microbiota?

(i) be able to detect specific micro-organism associated molecular patterns (MAMPs)

I. Their surface structures (lipopolysaccharide, peptidoglycan, flagellin, etc.)

II. Genomes of Cnidarians encode homologues of proteins capable of recognizing micro-organisms and their

associated molecular patterns

(ii) excrete broadly active antimicrobial compounds to select against general environmental organisms,

For example:

Antimicrobial peptide Damicornin was most active against a fungus and some (but not all) Gram-positive

bacteria, and had no effect on the four tested vibrios

(iii) release chemical cues and/or nutrients that would attract micro-organisms

Organic extracts of the coral Siderastrea siderea showed selective antimicrobial activity against two of four strains

of Gram-positive bacteria isolated from coral surfaces

Exposure of corals to pathogens also induces production of enzymes with predicted defence functions:

Phenoloxidase,

Peroxidases

Chitinases,

Melanin

Coral microbiota can change based on environmental conditions

Contact between corals and macroalgae can lead to changes in microbial assemblages in corals

Macroalgae may affect coral-associated microbes by

(i) smothering coral tissues or creating persistent hypoxic conditions

(ii) poisoning any member of the coral holobiont via algal secondary metabolites

(iii) Harbouring pathogenic bacteria

(iv) inhibiting or stimulating microbial growth by releasing dissolved organic carbon or antibiotic secondary metabolites

The major bacteria

Nitrogen-fixing

Bioluminescent

Gliding myxobacteria

Diversity of marine bacteria associated with Soft Coral

38 %

Gamma

proteabacteria

17%

Alpha

proteabacteria

13 %

CFP Group*

6%

Cyanobacteria

CFP Group*: includes: cytophagea,flavobacter/flexibacter, bacteriodes

Microbial Community Associated with the Zoanthid Palythoa australiae from the South China Sea

Phylogenetic tree of identified

isolates associated with the soft

coral Sarcophyton glaucum

Marine actinobacteria associated with marine organisms

Large number of new compounds with pharmacological potentials from the actinobacteria associated with the

marine organisms

polyketides,

isoprenoids,

phenazines,

peptides,

indolocarbazoles,

and sterols

Distribution and abundance of actinobacteria associated with the marine organisms

Natural products derived from the marine organism-associated actinobacteria

Distribution of natural product-producing actinobacteria associated with the marine organisms

All these natural products were isolated from the

genera belonging to Actinomycetales

Polyketide Synthases : PKSs are a family of large, modular enzymes that produce PKs, a large class of secondary metabolites,

in bacteria, fungi, plants and vertebrate lineages

PKSs found in I. actinobacteria,

II. mycobacteria,

III. pseudomonas

IV. cyanobacteria

Polyketide synthases are a class of enzymes that are involved in the biosynthesis of secondary metabolites

(erythromycin, rapamycin, tetracycline, lovastatin, and resveratrol)

Non-Ribosomal Peptide Synthetase

NRPs are peptide-derived molecules not produced by the ribosome but synthesised by assembly-line enzymes (NRPSs)

whose function is similar to that of PKSs

only eight approved drugs of bacterial orgin

12 NPs (or derivatives) in different clinical phases

In 2013, 1163 new marine compounds BUT

.و کشت اکتینوباکترهای دریاجداسازی تکنیک های

why more than 70 bacterial phyla have no cultured representatives

Many organisms require special growth parameters (physical and chemical) that are hard or even impossible to

reproduce in the laboratory

1% of coral bacteria can presently be cultured

Our knowledge is still poor about specific, natural nutrients and growth factors required for their cultivation.

I. Effects of uncommon inorganic elements, such as lithium, silicon, etc., which are also abundant in marine

sediments.

I. Common media constituents such as simple sugars, peptone

replaced with complex carbon sources such as chitin, sulfated polysaccharides, and marine proteins

Marine metagenomics, a valuable tool for enzymes and bioactive compounds discovery

Using metagenomics technique to access the uncultured majority of microbial communities

The enormous potential in diversity of the marine life is still not fully exploited due to the difficulty in culturing

many of the microorganisms under laboratory conditions.

Metagenomics

Using database sequences as a starting point,

I. we can clone biosynthetic genes directly from the symbiosis

II. and reconstitute them in a heterologous host for expression and compound production

Culture-free techniques

Metagenomic-based strategies are powerful tools to isolate and identify enzymes with novel biocatalytic activities

from the uncultivable component of microbial communities

Culture-free techniques

I. 16S r DNA library was constracted by isolation of DNA directly from the coral sample,

II. PCR amplification with bacterial-specific primers

III. coloning

I. We can obtain sequence information from ribosomal RNA (rRNA) genes directly from the symbiosis

without cultivation,

II. and design specific oligonucleotide probes from these sequences

Metagenomics may be focused on gene clusters or genes encoding enzymes and on the discovery of biocatalysts

for synthesis and production of secondary metabolites like bioactive compounds

S AVE OUR COR AL