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.