Introduction
The Earth’s covered by 70% of water molecules, which comprise 80% of
all biological organisms. Aquatic vegetation is more diversified than
their terrestrial counterparts. Bacteria play a vital role in the marine
environment. They drive biogeochemical cycles, deliver resources and
bring energy to higher tropical levels. Marine biofilm easily colonies
on man-made surfaces, quickly inducing corrosion, biofouling, and
possibly affecting polyethylene plastic buoyancy
(de Carvalho, 2018). Bacteria within biofilm are shown to control
physiological co-operation and spatial organization in order to increase
metabolic potential and resistance to fluctuations in the local
environment (Chew & Yang, 2015). In general, the interaction of
microbial cells with the substrate surface under specific
physico-chemical and nutritional conditions at the seawater surface
interface contributes substantially to the initiation and success of
microbial surface colonization in marine environments. Physico-chemical
properties of the substratum such as surface free energy, electrostatic
charge, hydrophobicity, wettability, roughness, micro topography,
vulnerability to wear (corrosion) and surface chemo-dynamic properties
of surface conditioning, nutrient enrichment, and charge accumulation or
alternation may influence the ability of microorganisms to adhere to a
particular abiotic surface. Chemical interactions of solutes with the
substratum’s surface, biological interactions of microbial cells with
the surfaces of other microbial cells, and specific gene regulation at
the population and community levels are all investigated. It plays a
main role in microbial surface colonization, modification of surface
physicochemical properties, structured biofilm development, and the
establishment and maturation of functional communities (Dang & Lovell,
2016). One of the strategies that microbes use to survive is believed to
be on biotic and abiotic surfaces because they offer significant
benefits, such as (i) Increased access to nutrients,
(ii) Protection against toxins and antibiotics, (iii) Maintenance of
extracellular enzyme activities, and (iv) Protection from predation. In
marine environments, bacteria play many roles, including driving the
biogeochemical cycles, supplying materials and bringing energy to higher
tropical levels Marine bacterial communities are known to play a key
role in the management of ecological and biogeochemical processes as
well as in the development of the ecosystem. Some microbes could have a
huge potential for producing a wide range of pigments and biomolecules.
Seasonal and geographical conditions influence natural characteristics
of marine bacteria such as color, therapeutic capabilities, and nutrient
synthesis such as vitamins, proteins, and lipids (C. Ramesh et al.,
2020).
Marine biofilms, also known as micro fouling, are organized communities
of mixed organisms that, along with diatoms and bacteria, are found in
the ocean. Quorum sensing is a bacterial cell-to-cell communication
process that regulates numerous important aspects of biofilm growth and
other phenomena. Quorum sensing controls a variety of processes by
acting as a simple communication network by secreting, accumulating, and
recognizing low molecular mass signaling compounds, which leads to the
expression of phenotypes that improve nutrient access, colonisation
rigidity, and community resistance to hostile environments (Salta et
al., 2013). Lanosterol identified from pigmented marine biofilm bacteriaKocuria rosea Ac. No KC505190 exhibits anti-biofilm activity and
anti-quorum sensing activity against dominated micro-fouling bacterial
groups by targeting their signaling protein molecules. Lanosterol
exhibited repellent activity by altering the signal transduction
pathways for modifying bacterial quorum sensing communication and thus
prevented biofilm formation. From the docking study, it has been found
that the lanosterol prefer hydrophobic nature to improve the binding
contacts of signaling proteins (Balasubramanian et al., 2018). There is
a huge potential for marine bacterial populations to synthesize a
variety of bioactive components, such as pigment molecules. The
synthesized pigments by bacteria are known as secondary metabolites that
help them survive in extreme environments. In order to survive in harsh
environments, stress, and cell damage, bacteria must evolve cell
adaption mechanisms, one of which is the synthesis of pigment. In frigid
climates like the Antarctic region, bacteria are exposed at even low
temperatures and continuous UV radiation creates pigment synthesis
(carotenoid, prodigiosin etc.), which protects cells from UV irradiation
and allows bacteria to survive in extreme environments. A quorum-sensing
mechanism regulates the production of these pigment molecules. In the
marine environment, pigments such as carotene, quinones, melanins,
prodiginines, tambjamine and violacein have been reported so far such as
Cytotoxicity, antioxidant, antibacterial, antimalarial, anticancer,
antitumor and antifouling characteristics etc., (C. Ramesh et al.,
2019). In this review, we pointed the importance of bioactive natural
pigments produced by marine biofilm bacteria.