Advanced nanocomposite membranes have been developed to meet the requirements of sustainable wastewater treatment, such as high separation efficiency, photocatalytic function, and anti-fouling ability in recent days. While several reviews individually addressed the application of carbon and TiO2 nanomaterials for wastewater treatment, the application of deep-sea derived nanoemulsions with carbon nanofiber (CNF)-TiO2 nanocomposite membranes and their associated Technology Readiness Levels (TRLs) and commercialization opportunities have not yet been comprehensively studied. Despite recent attention, the use of deep-sea microorganisms for biosurfactant-based functional nanoemulsion production remains largely unexplored. This review critically examines recent advances in multifunctional membrane systems incorporating carbon-based nanomaterials, TiO2 nanoparticles and biosurfactant-assisted nanoemulsion from deep-sea mixotrophic microorganisms. Additionally focuses on improvement of membrane properties using carbon nanomaterials and discusses engineered carbon-TiO2 interfaces that optimize photocatalytic degradation and antimicrobial activity by charge separation and reactive oxygen species (ROS) generation. Design and optimization of interfacial interactions for better electron transport and membrane performance was discussed in detail for CNF based TiO2 nanocomposite membrane. Integration of material design, interfacial engineering, deep-sea biosurfactant-assisted nanoemulsions, and TRL- and SDG-based perspectives provide a roadmap for developing and commercializing next-generation nanocomposite membranes. Current challenges, including nanoparticle aggregation, stability of membranes, production of biosurfactants at large scale, long-term operational performance are discussed. Future studies should focus on multifunctional CNF-TiO2 membranes with deep-sea biosurfactant-assisted nanoemulsions to improve dispersion, electron transfer, recombination suppression and mechanical strength for sustainable wastewater treatment. The results will be commercialized and applied as the development of smart bio-nano interfaces, AI powered reactor design and green scalable manufacturing could speed up the functionality. Overall, this review provides a critical roadmap for deep-sea biosurfactant-assisted CNF-TiO2 nanocomposite membrane technologies from fundamental research to scale-up and commercialization to treat wastewater.

This investigation evaluated the biostimulating efficacy of Sargassum extracts on the in vitro culture systems of the macroalga Ulva intestinalis and the microalga Chlorella sorokiniana. Extracts from Sargassum polycystum (BSA) and Sargassum wightii (BSB) were prepared using hot-water extraction and incorporated into growth media at 0.1

Fucoxanthin (FX), a bioactive carotenoid derived from Isochrysis galbana, exhibits significant therapeutic potential; however, its application is limited by poor physicochemical stability and low oral bioavailability. To overcome these limitations, FX-loaded chitosan-carrageenan nanoparticles (FX-CS/CRG-NPs) were developed via ionic complexation and optimized using a Box-Behnken design, with the CS:CRG ratio, Tween 80 concentration, and FX loading as independent variables. The optimized formulation (CS:CRG 1:0.12 w/w, 0.70% Tween 80, and 1 mg FX) yielded nanoparticles with a hydrodynamic diameter of 374 ± 19 nm, a zeta potential of +52.8 ± 1.0 mV, and an encapsulation efficiency (EE) of 85.2 ± 3.0%. Compared with free FX, the optimized nanoparticles exhibited significantly enhanced stability, retaining 21.51 ± 0.46% after 12 h at 60 °C and 40.51 ± 0.48% after 12 h of UV exposure, corresponding to 3.1- and 4.6-fold increases, respectively. During 60 days of storage, encapsulated FX retained 81.6 ± 1.37% at 4 °C and 24.69 ± 4.97% at 25 °C, whereas free FX showed markedly higher degradation. Simulated gastrointestinal digestion demonstrated improved stability and intestinal bioaccessibility, with recovery values of 82.86 ± 4.92% and 75.67 ± 2.96% for encapsulated FX, compared with 33.21 ± 5.43% and 29.36 ± 2.89% for free FX. In vivo, oral administration resulted in a 3.4-fold increase in plasma fucoxanthinol (FXOH) and a threefold increase in hepatic FXOH, indicating enhanced systemic exposure at the selected time point. Overall, CS/CRG nanoencapsulation significantly improves the stability and gastrointestinal performance of fucoxanthin, supporting its potential as an effective nanodelivery platform.

Microplastics, a complex category of pollutants containing microorganisms and toxins, pose a significant threat to ecosystems, affecting both biotic and abiotic elements. The plastisphere's bacterial community differs significantly from nearby habitats, suggesting they may significantly contribute to the degradation of plastic waste in the ocean. This study evaluated the diversity of culturable bacterial populations attached to the microplastics in the coastal zones of the A&N Islands and their potential for plastic degradation. Three A&N Islands beaches were surveyed for microplastics. Low-density polyethylene (LDPE) was the most abundant polymer found, followed by Acryl fibre, polyisoprene etc. A total of 24 bacterial isolates were chosen based on their morphological traits and underwent the initial screening processes. With the highest degrading activity (10.79 %), NIOT-MP-52 produced noteworthy results. NIOT-MP-25 (5.07 %), NIOT-MP-43 (3.78 %), NIOT-MP-61 (3.51 %), and NIOT-MP-82 (3.36 %) were the next most active strains. Strain NIOT-MP-52, selected for its superior degradation efficiency, underwent further screening and analysis using FT-IR, SEM, AFM, and DSC. Variations in infrared spectra indicated the breakdown of LDPE while SEM and AFM analyses showed bacterial attachment, roughness, grooves, holes, and pits on the LDPE surface. DSC provided thermal analysis based on the biodegradation potential of the bacterial strain targeting LDPE sheets. These findings highlight the ability of marine bacteria to efficiently degrade microplastics and utilize plastics as an energy source, emphasizing their importance in future plastic waste management.

This study investigated seasonal variations of thraustochytrids in rhizosphere soil collected from two mangrove species Rhizophora apiculata and Avicennia marina in natural and planted mangrove stands. Thraustochytrid counts were higher in the natural mangrove stand than in the planted site. The counts varied seasonally, being highest in the post-monsoon season followed by summer, monsoon, and pre-monsoon. Thraustochytrid counts exhibited positive correlations (p < 0.01) with counts of Total heterotrophic bacteria (THB), azotobacters, actinobacteria, fungi, yeasts, and Trichoderma. However, a negative correlation was observed with cyanobacteria. The counts also had positive correlation with silt, clay, nitrogen, phosphorus, potassium, chromium, copper, magnesium, cadmium, zinc and redox potential, but, negative correlations with temperature, pH, pore water salinity, total organic carbon and sand content of the soil samples. In the present study, 113 thraustochytrid strains were isolated from mangrove habitats. However, only 48 pure cultures survived after being sub-cultured three times. Based on survivability, color, and shape, two isolates from each sampling site in each season were selected. The predominant 24 isolates were identified based on their morphological, and molecular characteristics and were classified under five genera: Thraustochytrium, Schizochytrium, Botryochytrium, Parietichytrium, and Aurantiochytrium. Among the isolates, Aurantiochytrium sp. (AKTSK-06) produced the highest biomass of 15.71 g/L in the post-monsoon season (January-March, 2023), and Aurantiochytrium sp. (PVTSK-03) accumulated the highest lipid content of 61.33%. Thraustochytrids were found to contain Omega-3 poly unsaturated fatty acids (PUFAs), such as EPA up to 8.89% in Aurantiochytrium sp. (VRTSK-01), DPA up to 9.65% in Aurantiochytrium sp. (AKTSK-03), and DHA up to 47.46% in Aurantiochytrium sp. (AKTSK-06). Thus, mangroves provide an ideal ecological niche for thraustochytrids with an abundant supply of omega-3 fatty acids for potential industrial applications.

The major objective of the study is to identify causative factors of pteropod swarms caused by Creseis acicula Rang, 1828 (Class: Gastropoda, Order: Pteropoda) and compare it with the swarms reported from different regions of the world. The study was carried out in Port Blair Bay, Andaman Islands. Sampling for biological-chemical parameters was carried out from eight sampling stations during southwest monsoon (August). Swarming of C. acicula was observed in the outer region of Port Blair Bay. The pteropod population was found maximum in Aberdeen Bay with 1765 Nos./m3 during the low-tide. Pteropod was the dominant zooplankton group in two stations. The water column was well mixed with temperature ranging from 28.1 to 28.7°C with a vertical gradient of 0.0–0.3°C and salinity ranging from 30.27 to 32.93 PSU with a vertical gradient of 0.1–0.3 PSU. In the zooplankton sample, almost all the pteropod shells were empty and there was no trace of organisms that escaped/released from the shell. From the observation of this study and other global studies, we hypothesize that this large number of C. acicula may be due to the aggregation of shells from nearby areas by oceanographic processes.

Island bays show different physico-chemical characteristics due to their connection with open ocean water and small catchment area, and the same is expected with the biological forms. Phytoplankton size structure significantly influences the function of pelagic food webs and is controlled by the ambient nutrient concentrations. To quantify the relationship between these two in a tropical island bay and to understand the controlling factors, we analyzed the chlorophyll-a concentration by partitioning into three size classes (0.2—2.0 µm, 2.0—20.0 µm and > 20.0 µm) for two seasonal observations in the Andaman Islands. During winter, the nano-phytoplankton (2.0 – 20.0 µm) dominated, while in spring, micro-phytoplankton (> 20.0 µm) dominated. It was observed that the bay had abundant nutrients, but low chlorophyll a concentrations in winter, whereas the scenario reversed in spring. The phytoplankton community exhibited significant seasonal differences between the inner and outer bay areas. The inner bay was dominated by the nano-phytoplankton in winter and micro-phytoplankton in spring, while nano-phytoplankton and pico-phytoplankton dominated the outer bay. The micro-phytoplankton showed a significant seasonal variation, while the other two functional groups did not. During winter, the micro-phytoplankton showed a good correlation with the nutrient silicic acid, and the nanoplankton correlated with nitrite, nitrate, silicate and TN (Total Nitrogen) implying nano-phytoplankton’s reliance on most of the nutrients including organic nutrient. During spring, micro-phytoplankton correlated with the nutrient nitrate, and the nano-phytoplankton correlated with the organic nutrient total nitrogen (TN) implying its reliance on the organic nutrient.

The escalating global demand for fish protein necessitates the expansion of aquaculture from land to sea, facilitated by floating sea cages. In this study, the National Institute of Ocean Technology (NIOT), Chennai, Tamil nadu conducted a pilot-scale culture of hatchery-reared cobia seeds (Rachycentron canadum) in HDPE collar floating cages (9 m diameter with a cultivable volume of 320 m(3)). These cages were strategically deployed at Olaikuda (Gulf of Mannar, Tamil Nadu) and Thuplipalem (Andhra Pradesh), representing semi-protected (SP) and open sea (OS) environments respectively. The evaluation focused on growth performance, with cobia seeds stocked in cages at an initial biomass of 150 g/m3 (SP) and 154 g/m(3) (OS), featuring an initial average weight of 32.49 +/- 1.77 g and a total length of 15.6 +/- 0.91 cm during stocking. In SP site, cobia exhibited significant growth, reaching an average weight of 3830 g in 270 days, with a specific growth rate (SGR) of 1.76% with a survival rate of 77%. In contrast, despite the longer culture period of 322 days at the OS site, lower average weight of 2550 g with an SGR of 1.35% with survival rate 62% at SP. Physicochemical and biological parameters at both sites remained within optimal ranges. Notably, the OS site experienced higher wave heights (ranging from 0.56 to 2.28 m); potentially impacting feeding patterns, high energy expenditure due to the exposed weather conditions resulted into reduced growth rate compared to the sheltered bay. This study aims to elucidate the comparative suitability of environmental settings and its economic feasibility for open sea cage farming.

Cancer is a global issue and hence various efforts are being made. Iron oxide is considered a significant biochemical agent in the biomedical arena for cancer treatment. Marine macroalgae-mediated iron oxides especially, magnetite (Fe3O4) nanoparticles (NPs) are a prospective alternative to diagnose and treat cancer owing to their fluorescent and magnetic properties. We intend to appraise the usability of the aqueous extract of Rosenvingea intricata (R. intricata) in Fe3O4 NPs synthesis and to study their cytotoxic effects against human hepatocarcinoma (Hep3B) and pancreatic (PANC1) cancer cells. In the present study, R. intricata were collected from the coastal region of South Andaman, India. Aqueous extracts of R. intricata were utilized to synthesize Fe3O4 NPs via the co-precipitation method. Phycosynthesized Fe3O4 NPs exhibited wide peak at 400–600 nm from ultraviolet–visible diffused reflectance spectroscopic analysis which validated the formation of NPs. Band edge emission peak at 660 nm in fluorescent spectra confirmed the quantum confinement in Fe3O4 NPs. Fourier transform infrared spectroscopy confirmed the role of R. intricata as a capping and reducing agent with functional groups such as O–H, C–H, C=O, N=O, C=C, C–O, C–N, and C–S arising from amino acids, polysaccharides, aliphatic hydrocarbons, esters, amides, lignins, alkanes, aliphatic amines, and sulfates. Physicochemical properties such as crystallite size (14.36 nm), hydrodynamic size (84.6 nm), irregular morphology, elemental composition, particle size (125 nm), crystallinity, and saturation magnetization (0.90007 emu/g) were obtained from x-ray diffractometer, dynamic light scattering, scanning electron microscopy, energy dispersive x-ray spectrometer, high-resolution transmission electron microscopy, selected area electron diffraction and vibrating sample magnetometer techniques, respectively. The cell viability showed dose-dependent cytotoxic effects and enhanced the apoptosis against Hep3B and PANC1 cancer cells. R. intricata extract capped Fe3O4 NPs could be the most appropriate and effective nanomaterial for cancer treatment and management.

The present study was carried out to investigate the phytoplankton distribution in tropical waters and its implication for establishing land-based ballast water treatment technology and test facility (BWTT-TF) as per the International Maritime Organization (IMO) guidelines. Samples were collected from the Swarnamukhi estuary (SE) and coastal locations on the east and west coast of India. The maximum phytoplankton density in the size group of >= 10 and < 50 mu m was recorded as 3002 cells/mL in estuarine waters and 172 cells/mL in coastal waters. Among the phytoplankton, Bacillariophyta and Pyrrophyta were observed at all locations, whereas Ochrophyta and Chlorophyta were found only at specific locations or during specific periods. According to IMO guidelines, the minimum required number of species (5) was observed at all the locations, but the minimum number of phyla (3) was not found at some locations. The IMO minimum required phytoplankton density (>1000 cells/mL) was observed only during the bloom period, whereas it was about 5-50 times lower during other periods. Taxonomic distinctness indices were used to examine the diversity beyond the conventional species count. The study found that the Buckingham Canal and Swarnamuki River upstream among the SE locations, and coastal stations of Pamanji and Tirunelveli among the coastal locations, are suitable sites to establish land-based BWTT-TF. Since the results indicate that achieving the IMO specified size group of >= 10 and < 50 mu m density in tropical waters was possible only during the bloom period, culturing phytoplankton surrogates and concentrating naturally available phytoplankton are recommended as alternate methods for establishing landbased ballast water treatment technology and test facilities.

Major anthropogenic activities surround the Port Blair Bay, while Aerial Bay remains as a pristine environment. A field study was carried out during the south-west monsoon season (July - August, 2011) in the two bays to compare the physico-chemical parameters and their effect on phytoplankton community structure. Among the physico-chemical parameters, water temperature (p < 0.01, n = 18), DO (p < 0.01, n = 18) and TP (p < 0.05, n = 18) showed significant variation between the Bays. Salinity and Redfield ratio (N:P) was lower in Aerial Bay as compared to Port Blair Bay; while the Si:N ratio was higher in the Aerial Bay. The average chlorophyll-a concentration as well as species richness was found to be higher in the Port Blair Bay as compared to the Aerial Bay. The highest phytoplankton density and centric diatom abundance were observed in Port Blair Bay. In Aerial Bay, the centric diatoms like Dactyliosolen fragilissimus (44.5 %) and Guinardia flaccida (7.1 %) dominated, while in the Port Blair Bay, the centric diatom Skeletonema costatum (25.0 %) and a pennate diatom Nitzschia closterium (24.3 %) dominated the phytoplankton. The phytoplankton community was influenced by the nutrients from the tidal mud flats and rain-fed rivulets in the Aerial Bay; while, in the Port Blair Bay, the phytoplankton abundance was influenced by nutrients from land runoff, inundated areas and anthropogenic sources.

Microplastics (MPs) are ubiquitous in the marine environment, yet information regarding their occurrence in the food web is limited. We investigated the concentration and composition of MPs in water and diverse zooplankton groups from the Arabian Sea basin. Forty-one zooplankton tows were collected with a bongo net (330 μm mesh) from the Arabian Sea in January 2019. MPs in the surface water varied between 0 and 0.055 particles/m3, with a relatively higher concentration (0.013 ± 0.002 particles/m3) in the central Arabian Sea. Though fibrous MPs were most abundant in the seawater (77.14 %), zooplankton prefers small fragments (55.3 %). The size of MPs was distinctly smaller (277.1 ± 46.74 μm) in zooplankton than that in seawater (864.32 ± 73.72 μm), and MPs bioaccumulation was observed in almost all the zooplankton functional groups. Polymer composition revealed polyamide, polyethylene, polypropylene, and PVC were abundant in water and zooplankton, suggesting that the textile, fishing, shipping, and packaging industries are significant sources. The prevailing northeasterly winds, strong West India Coastal Current, and conducive westward radiated Rossby wave during January 2019 have carried the microplastic contaminated water mass away from the coast, posing a threat to the open ocean ecosystems. These results demand further attention to investigate the state of plastic pollution in the Arabian Sea basin.

In this study, a total of 1125 actinobacteria were isolated from the selected mangrove species: Avicennia marina , Rhizopora mucronata and Ceriops tagal from three study stations viz., Minnie Bay, Carbyn’s Cove and Burmanallah. Among these three stations, the highest number of actinobacteria was recorded in Carbyn’s Cove (64.97%), followed by (25.51%) at Burmanallah and the minimum of (9.51%) was recorded in Minnie Bay. Maximum number of actinobacteria was recorded from Ceriops tagal (40.44%) than the other selected mangrove species Avicennia marina (34.13%) and Rhizopora mucronata (25.42%). Among the 1,125 mangrove-associated actinobacteria, 103 morphologically different isolates from the Minnie Bay station was selected for the further characterization studies. In antibacterial assay, 30.11% of the isolates revealed inhibitory activity against all tested clinical pathogens and 65% isolates displayed inhibitory activity against minimum of 04 tested clinical pathogens. Growth survival studies of the actinobacterial isolates also accomplished to withstand in varied NaCl and pH levels. Of 103 isolates, all were found to synthesize gelatinase enzyme, 73 isolates demonstrated amylolytic activity, 38 isolates exhibited proteolytic and 63 isolates displayed urease activity. Interestingly, 56 isolates exhibited excellent DNase activity and 71 isolates revealed positive for l -asparaginase production. To our recognition, 11 isolates exhibited constructive results in the production of 06 extracellular enzymes of industrial importance. Of 103 isolates, 48 isolates were confirmed by molecular level identification. Based on the phylogenetic analysis, the isolates were categorized under the genera: Streptomyces, Nocardiopsis, Salinispora and Actinomadura.

A total of 143 isolates of aerobic, heterotrophic bacteria were isolated from the gut, peristomial membrane, spine, tooth and coelomic fluid of sea urchin, Diadema savignyi and Echinometra oblonga from the Port Blair costal area of South Andaman. Agarolytic bacterial strain that decomposes the cell walls of some seaweeds solid agar and agarose has been isolated from peristomial membrane of Echinometra oblonga. This strain has been identified as Vibrio sonorensis NIOT_SU2 C 9(b). Agarase- NIOT_SU2 C 9(b) from the culture medium was isolated and purified 47.78-fold from the culture fluid by a combination of ammonium sulfate precipitation, dialysis and successive purification by DEAE cellulose column chromatography. Purified protein migrated as a single band (46 kDa) on sodium dodecyl sulfate-polyacrylamide gels. The optimum pH and temperature of the agarase were 7.6 and 30-35°C, respectively. However, it maintained as much as 85% of the maximum activities at wide range of temperatures and also highly specific for its substrate, this enzyme did not decompose sodium alginate. Furthermore, this work is the first evidence of cold and temperature-adapted agarase from sea urchin associated bacteria and these results indicate the potential for the agarase-NIOT_SU2 C 9(b) as a catalyst in medicine, food, cosmetic industries and practical application in gene technology.

The omnipresent accumulation and non-degradable nature of plastics in the environment are posing an ever-increasing ecological threat. In this study, a total of 97 bacteria were isolated from macroplastic debris collected from the coastal environments of Andaman Island. The isolates were screened for LDPE degradation potential and were identified based on phenotypic, biochemical, and molecular characterization. 16S rDNA-based identification revealed that three-three isolates of each belong to the genus Oceanimonas and Vibrio, two were closely related to the genus Paenibacillus whereas, one-one was associated with the genus Shewanella, Rheinheimera, and Bacillus, respectively. A bacterial consortium was formulated using the top four isolates based on their individual LDPE degradation potentials. A significant increase (p < 0.05) in the mean LDPE degradation (47.07 ± 6.67% weight-loss) and change in thickness was observed after 120 days of incubation. FTIR spectrum, 13C NMR, and TG-DSC analyses demonstrated changes in the LDPE sheets' functional groups, crystallinity, and in thermal properties after 120 days of incubation. The SEM and AFM images confirmed bacterial attachments, an increase in surface roughness and deformities on LDPE sheets. This study reports a bacterial consortium that can efficiently degrade the plastics and can be used in providing eco-friendly mitigation of plastic waste.

The marine environment is most vital and flexible with continual variations in salinity, temperature, and pressure. As a result, bacteria living in such an environment maintain the adaption mechanisms that are inherent in unstable environmental conditions. The harboring of metal-resistant genes in marine bacteria contributes to their effectiveness in metal remediation relative to their terrestrial counterparts. A total of four mercury-resistant bacteria (MRB) i.e. NIOT-EQR_J7 (Alcanivorax xenomutans); NIOT-EQR_J248 and NIOT-EQR_J251 (Halomonas sp.); and NIOT-EQR_J258 (Marinobacter hydrocarbonoclasticus) were isolated from the equatorial region of the Indian Ocean (ERIO) and identified by analyzing the 16S rDNA sequence. The MRBs can reduce up to 70% of Hg(II). The mercuric reductase (merA) gene was amplified and the mercury (Hg) volatilization was confirmed by the X-ray film method. The outcomes obtained from ICP-MS validated that the Halomonas sp. NIOT-EQR_J251 was more proficient in removing the Hg from culture media than other isolates. Fourier transform infrared (FT-IR) spectroscopy results revealed alteration in several functional groups attributing to the Hg tolerance and reduction. The Gas Chromatography-Mass Spectrometry (GC-MS) analysis confirmed that strain Halomonas sp. (NIOT-EQR_J248 and NIOT-EQR_J251) released Isooctyl thioglycolate (IOTG) compound under mercury stress. The molecular docking results suggested that IOTG can efficiently bind with the glutathione S-transferase (GST) enzyme. A pathway has been hypothesized based on the GC-MS metabolic profile and molecular docking results, suggesting that the compound IOTG may mediate mercuric reduction via merA-GST related detoxification pathway.

Plastic is a wonder product, perhaps one of humanity's best innovations, and has become an indispensable part of our daily lives. Besides the indisputable benefits of plastic materials, significant concerns arise about plastic leakage to the environment. Tiny plastic particles, so-called microplastics (MP), have been detected ubiquitously in various ecosystems around the globe. They are bioavailable for many organisms and may negatively affect ecosystems and society, and the economy. The present study was conducted at first to understand the nature, behavior, and interactions of microscopic plastic waste in the marine environment. A preliminary study was conducted in the coastal environment from the Andaman Sea to map the current plastic pollution status and establish baseline data MPs in water, sediment, and marine food web. In this work, clear evidence of MP bioaccumulation was observed in the marine food-chain organisms like zooplankton, finfishes, and shellfishes. A high amount of MP retention was observed in the zooplankton community. Maximum MP ingestion was observed in adult carangid fish Carangoides malabaricus (up to 67 micro-particles/fish). FT-IR revealed many anthropogenic polymers like polyethylene, polypropylene, nylon, acrylic, and ionomer surlyn. These results depict that plastic pollution is ubiquitous and reached almost every compartment of the coastal environments. Further, to understand the plastic pollution hotspots in the Indian marine environments, a comparative study was carried out to assess the abundances and characteristics of MPs in the bottom sediments from the continental shelf zone of the Andaman Sea and the Arabian Sea. Surface sediments were collected onboard FORV Sagar Sampada from 14 locations of the Andaman Sea and 8 locations of the Arabian Sea with a depth varied from 76 to 264 m. Microplastics were isolated using density separation methods and were enumerated using light microscopy and epi-fluorescence microscopy. MP concentration ranged from not detected (ND) to 267 particles per kilogram. Mean MP concentration at the Arabian Sea was significantly higher (p < 0.001) than in the Andaman Sea. Among different types of MPs, fiber had the highest distribution, followed by fragment and pellet. The mean MP concentration at the Arabian Sea was significantly higher than the Andaman Sea, suggesting the Arabian Sea experiences more anthropogenic pressures than the former area. The present study revealed the widespread occurrence of MPs throughout the Indian seas. Further, to understand the ecological consequences of these microscopic litters, MP ingestion by oceanic zooplankton of the Arabian Sea was analyzed. Clear evidence of higher amounts of MP ingestion was observed in carnivorous zooplankton than in the herbivorous or omnivorous species. These results suggest that feeding habits play critical roles in the pollutants' availability in the marine environment. The plastic pollution problem is magnifying due to the long-term persistence and prolonged degradation of plastics in the environment. Omnipresent accumulation, persistence, and environmental toxicity of plastic waste warrant immediate action for developing efficient, eco-friendly, and sustainable technologies for their degradation. However, some of the microbes, including bacteria, are capable of synthetic polymer degradation. To understand whether microbes can play a critical role in solving the plastic pollution, 11 marine bacteria with plastic degradation potentials were isolated from the coastal environments of Andaman Island. Further, based on the preliminary screening, a bacterial consortium was prepared with four bacterial strains from the genus Vibrio (2 strains), Paenibacillus, and Bacillus. The bacterial consortium was incubated with low-density polyethylene (LDPE) sheets as sole carbon source and incubated for 120 days. After 120 days of incubation on average, nearly 47% LDPE degradation was observed. These observations were supported with FT-IR, SEM, AFM, NMR, and TG-DSC analysis. These results suggest that the bacterial consortia used in this work may have great potential to degrade plastics and solve the problem. However, further research is required to develop innovative, cutting-edge, and eco-friendly technology to solve plastic pollution.

A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz., point of the eruption (M), middle of the volcano (MD), and the dried part of the mud volcano (E). Based on the biochemical and molecular characterization, the isolates were categorized under the phyla Proteobacteria, Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes. Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid (IAA) production. Excellent antagonistic property, plant growth promoting properties such as IAA production, phosphate, potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates. In this study, we investigated the optimization of IAA production by B . megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development. Maximum IAA yield was achieved using optimal conditions (42.63 mg/mL) in the presence of optimized tryptophan after 4 days of incubation. Twofold increase in the plant growth parameters were observed to that of control plants. Optimization of culture conditions resulted in a fourfold increase in IAA production by B . megaterium NIOT_MV 31 cells. The results clearly demonstrated that, B. megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.

This study explores the possibilities of converting the largely underutilized potential coastlines of Andaman Island to profitable seaweed farming sites, particularly at South Andaman. Present study, surveyed a total of five stations to locate the best possible site for seaweed mass production, of which two locations were selected based on geomorphology, water quality parameters and ease of access. The pilot scale study was done from 2018 – 2021 to understand the feasibility of seaweed farming in this Island. The first culture initiation was done at North Bay using Gracilaria edulis ( G. edulis) and Acanthophora spicifera ( A. spicifera) in floating bamboo raft . Seaweeds were tied using two different methods i.e.direct insertion to ropes and pouch filling. The results suggested that pouch filling method not only increases the yield but also lowers wash out occurrences in rough sea. The G. edulis species was found to grow well in the bamboo rafts with DGR of approximately 135 gm (± 0.085gm)/Kg. About 155–180 kg of G.edulis were harvested from 7 raft seasonally with 17.5 kg of input biomass, in this trial study. The main challenges experienced during the trial were, seasonality of preferable seed material, prolonged rainy seasons, cyclonic events, wave action and turbidity due to sedimentation, fouling by undesirable algae. Even so, the prospects of extensive development of seaweed culture in these islands are high, provided, steady seed availability, selection of season, proper culture technique and practices are considered and applied.

A total of 143 isolates of aerobic, heterotrophic bacteria were isolated from the gut, peristomial membrane, spine, tooth and coelomic fluid of sea urchin, Diadema savignyi and Echinometra oblonga from the coastal area of Marina Park, Port Blair, South Andaman. The bacterial strain with agarolytic potential has been identified as Vibrio sonorensis NIOT_SU2 C 9(b). Agarase-NIOT_SU2 C 9(b) from the culture medium was isolated and purified with 47.78-fold from the culture fluid by a combination of ammonium sulphate precipitation, dialysis and successive purification by DEAE cellulose column chromatography. Purified protein migrated as a single band (46 kDa) on sodium dodecyl sulphate-polyacrylamide gels. The optimum pH and temperature of the agarase were 7.6 and 30–35 °C, respectively. Agarase enzyme maintained as much as 85% of the maximum activities at wide range of temperatures and this enzyme did not decompose sodium alginate. This work is the first evidence of cold and temperature-adapted agarase from sea urchin associated bacteria and the results of this study authenticated the potential for the agarase-NIOT_SU2 C 9(b) as a catalyst in medicine, food, cosmetic industries and practical application in gene technology.