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Heavy infestation by Perna viridis has been observed in the sub-seabed seawater intake tunnel and CWS of a tropical coastal power station in-spite of continuous low dose chlorination regime (0.2 ± 0.1 mg L−1) (CLDC), indicating periodical settlement and growth. Continuous arrival of mussels (colonized in the sub seabed tunnel intake section) at the pump house indicated that the mussels were able to tolerate and survive in a chlorinated environment, for varying time periods and were dislodged when they become weak and subsequent death, leading to flushing out of the system. In the present study, effect of continuous chlorination [0.2 mg L−1 (in-plant use); 0.5 mg L−1 (shock dose) & 1.0 mg L−1 (high levels)] was evaluated on mussels to assess; (a) time taken for mortality, (b) action of chlorine on physiological, genetic, metabolic and neuronal processes. 100% mortality of mussels was observed after 15 (0.2 mg L−1); 9 (0.5 mg L−1) and 6 days (1.0 mg L−1) respectively. Extended valve closure due to chlorination resulted in stress, impairing the respiratory and feeding behavior leading to deterioration in mussel health. Pseudofaeces excretion reduced to 68% (0.2 mg L−1); 10% (0.5 mg L−1) and 89% (1.0 mg L−1) compared to controls. Genotoxicity was observed with increase in % tail DNA fraction in all treatments such as 86% (0.2 mg L−1); 76% (0.5 mg L−1) and 85% (1.0 mg L−1). Reactive Oxygen Species (ROS) stress biomarkers increased drastically/peaked within the first 3 days of continuous chlorination with subsequent quenching by antioxidant enzymes. Gill produced highest generation of ROS; 38% (0.2 mg L−1); 97% (0.5 mg L−1); 98% (1.0 mg L−1). Additionally, it was shown that 84% (0.2 mg L-1), 72% (0.5 mg L-1), and 80.4% (1.0 mg L-1) of the neurotransmitter acetylcholinesterase activity was inhibited by chlorine at the nerve synapse. The cumulative impact of ROS generation, neuronal toxicity, and disrupted functions weakens the overall health of green mussels resulting in mortality. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Vibrio harveyi is a predominant pathogen cause vibriosis in shrimp aquaculture. • Whole-genome sequencing provides genomic molecular structure of V. harveyi RT-6. • 5730 protein-coding genes, 11 rRNAs, 114 tRNAs and 57 RNAs were annotated. • 13 complete insertion sequence elements were identified in the V. harveyi RT-6. • An incomplete prophage region was identified in the V. harveyi RT-6. Abstract The pathogenicity of "Vibriosis" in shrimps imposes prominent menace to the sustainable growth of mariculture economy. Often the disease outbreak is associated speciously with Vibrio harveyi and its closely related species. The present study investigated the complete genome of the strain V. harveyi RT-6 to explore the molecular mechanism of pathogenesis. The genome of V. harveyi possesses a single chromosome of 6,374,398 bp in size, G + C content (44.7%) and 5730 protein coding genes. The reads of 1.3 Gb were retained from Illumina Hiseq 2500 sequencing method, assembled into 5912 predicted genes, 114 tRNAs genes, and 11 rRNAs genes. Unigenes were annotated by matching against Clusters of Orthologous Groups of proteins (COG)-5730, Gene ontology (GO)-1088, and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases-3401. Furthermore, 13 insertion sequences-(IS), virulence factors and prophage regions were also identified. A total of 94 pathogenic genes and 36 virulence factor genes were mainly identified using Virulence Factors Database (VFDB). Out of the 36 virulence factors, 23 genes responsible for encoding flagella-based motility protein were exclusively predicted to take part in pathogenic mechanism. The Whole Genome Sequencing (WGS) of the strain RT-6 (accession number: SRR5410471) highlighted the underlying genes and specifically accountable functional genes that were responsible for pathogenic infections in shrimps. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Antifouling potent "Pyrrolo" isolated from Marine sponge associated bacterium. • FT-IR, HPLC, GC MS and FT-NMR characterization identified the bioactive Pyrrolo. • Pyrrolo inhibited the growth of fouling bacterial strains. • Molecular docking studies confirmed the antifouling potential of the active Pyrrolo. • Antidiatom and Mussel byssal thread inhibition confirmed the potential of Pyrrolo. Abstract In the present study, an attempt has been made to explore the antifouling potential of bioactive compound isolated from sponge associated bacterium Halobacillus kuroshimensis SNSAB01. The crude extract of SNSAB01 strongly inhibited the growth of fouling bacterial strains with least minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive compound was characterized through FT-IR, HPLC, GC MS and NMR predicted as 'pyrrolo". From the mass spectral library, structure was elucidated as pyrrolo [1, 2-a] pyrazine-1, 4-dione, hexahydro. The in silico studies provided encouraging docking scores with two interactions by GLN 200 and GLU 304. The extract inhibited 89% diatom adhesion at 350 μg/ml concentration against Amphora sp. An EC 50 value of 150 μg/ml for 50% inhibition of byssal thread of Perna viridis and LC 50 was found to be 500 μg/ml. The LC 50 /EC 50 ratio of 3.0 indicated nontoxic to nature. The result suggested that pyrrolo[1,2- a ]pyrazine-1,4-dione can be used for antifouling coating. [ABSTRACT FROM AUTHOR]

Objectives This study aimed to sequence the whole genome of Vibrio campbellii RT-1 strain. Methods V. campbellii strain was isolated from an infected shrimp, Litopenaeus vannamei collected from aquaculture ponds, India (12.1899° N, 79.9249° E). The whole genome sequencing (WGS) was performed using the Illumina Hiseq 2500 platform and assembled de novo using SPAdes and Velvet optimiser. Furthermore, the gene prediction and annotation were performed by a rapid prokaryotic genome tool-Prokka. Results The genome of V. campbellii RT-1 strain has one circular chromosome with 6327218 bp long. V. campbellii RT-1 strain contains 5787 predicted genes with an average of 45% GC content. A total of 86 known genes associated with pathogenicity were identified and 28 genes were found to be responsible for virulence factors. Furthermore, 1112 unigenes were subjected to Gene Ontology (GO) terms, and 4895 predicted proteins were annotated with Clusters of orthologous (COGs) functional groups. Conclusions The phylogenetic position of V. campbellii RT-1 strain was established through whole genome sequencing and genomic tools which provides a strong platform to further study on genomic alterations and phenotype of V. campbellii . [ABSTRACT FROM AUTHOR]

The knowhow followed for synthesis, characterization and application of nanomaterials has become an important branch of nanoscience. The use of marine sponges for the synthesis of metal nanoparticles is still in the budding level of current nanobiotechnology. This paper reports a single step one pot biosynthesis utilizing marine sponge ( Haliclona exigua ) extract as a reducing agent by means of a conventional ultrasonic bath on the formation and growth of flower like silver nanocolloids. These silver nanocolloids were characterized through UV visible spectroscopy, High Resolution Transmission Electron Microscope, Fourier Transform Infrared spectroscopy and X-ray Diffractometer. Further, antibacterial activity and antiproliferative activity were done against oral biofilm bacteria and oral cancer cell lines for the biosynthesized flower like silver nanocolloids. Water soluble organic amines were responsible for the syntheses of nanomaterials which have a size range from 100 to 120 nm. An average size of 9.1 mm zone of inhibition was recorded with 10.0 μg of silver nanocolloids against oral biofilm bacteria. The estimated half maximal inhibitory concentration value for flower like silver nanocolloids was 0.6 μg/ml for oral cancer cell lines. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated the effect of biogenic silver nanoparticles against marine biofilm forming bacteria. [•] Aspects such as formation of circular zone, quantification of biofilm formation and bacterial growth were assessed in the presence and absence of silver nanoparticles. [•] Marine biofilm bacteria were found to be controlled in the presence of silver nanoparticles. [ABSTRACT FROM AUTHOR]

Liposomes were prepared in the laboratory with lipids obtained from chicken egg yolk to encapsulateSpirulinapowder.Artemianapulii were hatched and fed with lipid-encapsulatedSpirulinaorSpirulinapowder. After 20 days of rearing, the experimentalA. salinawere harvested and measured for total body length and total content of protein and carbohydrates. Total body length was 45% higher, protein content was 49% higher, and carbohydrate was 35% higher inArtemiafed with liposomes as compared with those fed onlySpirulinapowder. [ABSTRACT FROM AUTHOR]

Abstract: The growing trend of exploring bacteria, fungi, actinomycetes and plant materials for the biosynthesis of nanoparticles is considered as eco friendly and a green technological approach. In this backdrop the present study reports the synthesis of gold (Au) nanoparticles from gold precursor using the extract derived from the marine sponge, Acanthella elongata (Dendy, 1905) belonging to the primitive phylum Porifera. Water-soluble organics present in the marine sponge extract were mainly responsible for the reduction of gold ions to nano-sized Au particles. The sponge extract added to 10–3M HAuCl4 aqueous solution at 45°C changed to pinkish ruby red color solution and confirm the bioreduction within 4h with continuous stirring. UV–visible spectrum of the aqueous medium containing gold nanoparticles showed a peak around 526nm. High-resolution transmission electron micrographs (HR-TEM) confirmed the monodispersed and spherical shaped with the size ranges from 7 to 20nm, however a maximum number of particles were in 15nm diameter. Through Fourier transform infrared spectroscopy (FT-IR) analysis, the reducing agent in the marine sponge extract was identified which is attributed for the biosynthesis of gold colloids. The XRD analysis respects the Bragg''s law and confirmed the crystalline nature of the gold nanoparticles. [Copyright &y& Elsevier]

This transcriptomic study for ice-ice diseased Kappaphycus alvarezii was done using Illumina sequencing technology. As many as 46 million raw reads were generated and after filtering the data, a clean read of 44 million was obtained. Further 59,942 uni-genes were obtained through De novo assembly with a mean length of 304 bp. Gene functional annotations were generated in respect to the non-redundant database (Nr), nucleotide sequence (Nt), Protein family (Pfam), Kyoto Encyclopedia of Genes and Genomes database (KEGG), SwissProt, Eukaryotic Orthologous Groups (KOG) database and the Gene Ontology database (GO). With respect to uni-genes, 47,725 (79.61%) unigenes were described in the minimum one database and 3351 uni-genes were described in entire databases. Functional annotation with GO extracted 24,903 uni-genes under three main domains. Gene interaction was scored using the KEGG pathway database with 125 pathways in which 8394 uni-genes were recognized. The study of enrichment of functional gene expression with a value greater than the FPKM average can reveal several essential pathways. Ice-ice diseased K. alvarezii mRNA transcripts were studied by Illumina sequencing technologyfor the potential changes in the level of genes and gene expressions. [Display omitted] • Ice-ice disease led to a significant disease in seaweed production and carrageenan yield. • Bacteria that hydrolyze carrageenan was identified and transcriptome investigated. • It also provided the insight into cell pathology and host response for causation. • Healthy and ice-ice disease in K. alvarezii and their molecular mechanisms were compared. • Transcript sequences of K. alvarezii is a valuable resource for potential gene identification. [ABSTRACT FROM AUTHOR]

The increasing use of natural products from marine organisms and their synthetic analogs as antifouling agents is replacing chemical biocides due to their ecological compatibility. This study evaluated the antifouling potential of pyrrolo compound (PC) from the sponge-associated bacterium Halobacillus kuroshimensis against the barnacle Amphibalanus reticulatus larval survival, metamorphosis and settlement in the laboratory. The successful concentrations were also subjected to field based static immersion tests to study the efficacy of the PC extract on macrofouling settlement. Results showed decreased naupliar survival and affected larval metamorphosis in a dose-dependent manner, with varying sensitivity among developmental stages. Higher PC concentrations significantly reduced cyprid yield and settlement, with over 50% of cyprid larvae failing to settle at concentrations of 1300 μg/ml and above. Field experiments confirmed a steady decline in barnacle settlement on PC-treated coupons, with less than 50% settlement observed at concentrations of 500–2000 μg/ml over 50 days. The LC 50 /EC 50 ratio for nauplius N-II was 1.11, with higher ratios observed in later stages and for the cypris (1.66), suggesting moderate toxicity and a narrow margin of safety. These ratios suggest barnacle settlement inhibition occurring through a toxic mechanism. The results demonstrate the compound's ability to disrupt barnacle settlement, but also raise concerns about its environmental impact (long-term usage), particularly the potential risks to non-target species before using the compound in real-world antifouling applications. Despite higher concentrations used compared to previous reports, PC shows potential as an effective natural antifouling compound. • Pyrrolo from Halobacillus kuroshimensis was reported for its antifouling potential. • Pyrrolo decreased the naupliar survival and disrupted larval metamorphosis. • Higher Pyrrolo concentrations significantly reduced cyprid yield and settlement. • Field trials showed less than 50% barnacle settlement on Pyrrolo -treated coupons. [ABSTRACT FROM AUTHOR]

Abstract: Biotic factors mediated biosynthesis of nanoparticles is considered as an eco friendly and green technological approach compared to chemical and physical methods. This work reports the biosynthesis of silver nanoparticles using the extract of marine sponge, Acanthella elongata. Water-soluble organics present in marine sponge extract were mainly responsible for the reduction of silver ions. UV–visible spectrum of the aqueous medium containing silver nanoparticles showed plasmon resonance peak at around 426nm. The X-ray diffraction pattern (XRD) of 2θ=38.1°, 44.3°, 64.5° and 77.4°, confirmed the crystalline nature of the silver nanoparticles. Transmission electron microscopy (TEM) analysis of silver nanoparticles indicated the sizes, ranging from 15nm to 34nm in diameter and a spherical shaped polydispersal of the particles. Through Fourier transform infrared spectroscopy (FT-IR) analysis the possible biochemical agent present in the marine sponge extract was identified as amines which were the cause for the bioreduction of silver salt to silver nanoparticles. [Copyright &y& Elsevier]

Phytoplankton production, succession and community composition is limited by nutrients, temperature and spectral properties. Elemental ratios serve as indicators for predicting productivity of phytoplankton including diatom. Deep ocean water (DOW) as a marine natural resource is rich in inorganic nutrients. In the present study, as part of the OTEC program, an initial attempt was made to characterize quantitatively the elemental ratios in DOW and relate to growth of the diatom, Chaetoceros sp. In addition, the production of Chaetoceros sp. in DOW was compared with a conventional nutrient enrichment medium, generally used for phytoplankton growth. To assess the productive ability of DOW, factorial experiments with Chaetoceros sp. were carried out with (i) unaltered DOW [100% DOW], (ii) admixtures [50:50] of DOW and surface seawater (SSW) [50% DOW], (iii) plain SSW, (iv) SSW enriched with nutrients and (v) DOW enriched with nutrients. Results of admixtures of seawater starting from 0% SSW to 100% DOW revealed optimum Redfield ratios at 50% dilution. Results on growth of Chaetoceros sp. in 100% DOW showed a sudden blooming on the 2nd and 3rd day. Chlorophyll 'a' values of 70 mg m−3 were obtained with DOW and SSW enriched with f/2 medium. Similarly with 50% DOW same chlorophyll 'a' concentrations was reached on the 4th 5th day and declined on the 6th day. Results of the present study demonstrate that 100% and 50% dilutions of DOW could be used for intensive culture of Chaetoceros sp. and that biomass production could be achieved within 3 days compared to incubations which use a conventional medium. • Levels of (nitrate, phosphate and silicate) nutrients increased with depth. • DOW has the potential for culture of phytoplankton compared to conventional mediums. • N: P ratio was found to be double in DOW from 1000 m depth. • 100% and 50% dilutions of DOW could be used for intensive culture of phytoplankton. [ABSTRACT FROM AUTHOR]

Discharge of nanomaterials into the environment contributes to a diverse group of pollutants. In the present study, the toxicity of selenium nanoparticles (SeNPs) on the marine diatom Chaetoceros gracilis was studied in the laboratory by conducting 96 h toxicity experiments. The SeNPs were synthesized by reducing sodium selenite using L -cysteine and characterized by spectroscopic and microscopic techniques. X-ray photoelectron spectroscopic (XPS) data showed a distinctive selenide peak at 56 eV, indicating the oxidation states Se3d 3/2 and Se3d 5/2. Raman spectra results indicated the characteristic A 1 and S mode of selenium (Se). Growth inhibitory experiments were performed (LC 50 14.63 mg/L) for 96 h using various concentrations of SeNPs and its membrane damage to cells was observed. Upon treatment with SeNPs, an increased percentage of reactive oxygen species (ROS) production was detected from 28.77±3.13% to 130.55±3.16% after 96 h. Malonaldehyde (MDA), a biomarker of lipid peroxidation was quantified and exposure to 50 mg/L of SeNPs significantly (p < 0.05) increased MDA concentration from 4.31±0.02 to 5.05±0.05 µM in 96 h. The morphological distortion, including cell wall damage, that affects the cellular integrity upon exposure to SeNPs was evident from microscopic studies. These results clearly indicate that, even at lower concentrations, SeNPs toxicity on lower trophic organisms is significant enough to cause cellular level alterations. [Display omitted] [ABSTRACT FROM AUTHOR]

Marine ecosystem comprises of microorganisms, plants, invertebrates and vertebrates which were rich source of diverse antimicrobial products, which were structurally unique belonging to a known class of macromolecules like peptides, terpenes, alkaloids and proteins, etc. Natural macromolecules from marine ecological niches are a promising source of antibacterial agents against several drug resistant strains of pathogenic microorganisms; whereas rest of the metabolites were derived from marine flora and fauna while some arise from microbes associated with living organisms. >30,000 natural macromolecules have been identified and reported from marine organisms, however only few macromolecules are being explored and validated. The discovery of marine antibacterial macromolecules plays a significant part in the field of drug discovery and biomedical research. Despite the fact that literatures were documented on the antifungal, antiviral, antimalarial and anticancer properties, this review exclusively highlights the different antibacterial natural macromolecules from marine sources like bacteria, fungi, sponge, algae, bryozoans, tunicates, corals, cnidarians, arthropods and echinoderm along with their mode of action. [ABSTRACT FROM AUTHOR]

The presence and longevity of nanomaterials in the ecosystem, as well as their properties, account for environmental toxicity. When nanomaterials in terrestrial and aquatic systems are exposed to the prevailing environmental conditions, they undergo various transformations such as dissociation, dissolution, and aggregation, which affects the food chain. The toxicity of nanomaterials is influenced by a variety of factors, including environmental factors and its physico-chemical characteristics. Bioaccumulation, biotransformation, and biomagnification are the mechanisms that have been identified for determining the fate of nanomaterials. The route taken by nanomaterials to reach living cells provides us with information about their toxicity profile. This review discusses the recent advances in the transport, transformation, and fate of nanomaterials after they are released into the environment. The review also discusses how nanoparticles affect lower trophic organisms through direct contact, the impact of nanoparticles on higher trophic organisms, and the possible options for remediation. • Ecotoxicological effect greatly depends on factors such size, shape, aggregation, and environmental factors. • A series of nano/bio interfaces formation occur when nanoparticles encounter cell, tissue, and organisms. • Uptake of nanomaterials is facilitated by process like phagocytosis, clathrin-mediated endocytosis, caveolae-dependent endocytosis, clathrin/caveolae independent endocytosis, and micropinocytosis. • Trophic transfer is crucial as nanomaterials consumed by lower-level organisms end up accumulating in higher organisms such as human beings. [ABSTRACT FROM AUTHOR]

Abstract: High density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) coupons were immersed for a period of 6 months in Bay of Bengal near Chennai Port (Port) and Fisheries Survey of India (FSI). Samples were retrieved every month and the extent of biofouling and biodegradation were monitored by measuring biological and physicochemical parameters. Dissolved oxygen and oxidation reduction potential were higher at Port than at FSI. Total suspended solids and organic matter were more on PP, followed by HDPE and LDPE indicating hydrophobic surfaces favour more biofouling. Pseudomonas sp., anaerobic, heterotrophic and iron-reducing bacteria were observed on polymer surface. Biofouling was found to depend on the season, loading being highest in the month of August. Chlorophyll was higher at FSI than at Port due to higher pollution levels and also being closer to the shores. Maximum weight loss was seen in LDPE (1.5–2.5%), followed by that in HDPE (0.5–0.8%) and finally in PP (0.5–0.6%) samples deployed at Port in the six month time period. [Copyright &y& Elsevier]

Abstract: Plate heat exchangers are often preferred in Ocean Thermal Energy Conversion (OTEC) plants because of the large area they provide for heat transfer leading to higher efficiencies and also because of the compact size of such heat exchangers. Tight control over heat exchanger cleanliness is required as the gap between successive plates is only 3.7mm and hence fouling can easily impede flow. Based on preliminary evaluation liquid sodium hypochlorite was selected as a possible biocide for fouling control in OTEC operation based on its effectiveness, easy availability, low cost and ease in mid sea replenishment of stock. Subsequently, experiments were conducted in near-shore waters, at residuals of 0.2, 0.5, 0.8, 1.0, 1.2 and in simulated flow chambers (Pederson device) and slime control was achieved at a continuous residual level of . A log reduction 0.8 times in bacterial density between control and chlorinated plates was observed at this regime. Later on experiments were conducted at an OTEC site (65km offshore off Tuticorin, on the east coast of India) by changing the regime to an intermittent mode, with a view to reducing the amount of chlorine carried on the OTEC barge. These studies showed that an intermittent chlorination regime of residuals, 2h on/2h off, was effective for slime control. Since the control of fouling is critical for heat transfer efficiency, the dose and frequency evolved in coastal and oceanic waters using flow chambers was validated using a model plate heat exchanger at the oceanic site onboard a research vessel. In these experiments, a significant log reduction (0.6 times) was observed in bacterial density between control and chlorinated plates in an intermittent mode of once for 2h. In addition, experiments were conducted by varying the frequency of chlorination from 0.5 to 2h at a dose of to gain a better understanding of biofilm development and the cleanliness efficiencies achievable for plate heat exchangers used for seawater applications. [Copyright &y& Elsevier]