Search

In the present study, the whole seaweed from Kappaphycus alvarezii (containing carrageenan) was used for preparation of bio-nanocomposite films by blending with metal oxide nanoparticles such as zinc oxide (ZnONPs), cupric oxide (CuONPs) and silicon dioxide (SiO 2 NPs) for multiple applications, and their properties were compared with standard refined κ-Carrageenan (commercial grade). Simultaneously, the antibacterial activity and biodegradation profile of the prepared bio-nanocomposite film were also studied. The incorporation of nanoparticles into the bioplastic film matrices altered the surface morphology, increased the roughness and significantly (p < 0.05) reduced the UV transmittance, water uptake ratio (WUR), moisture content and solubility in both standard carrageenan-based bio-nanocomposite films (CBF) and Kappaphycus- based bio-nanocomposite films (KBF) compared to control. The average roughness (Ra) of KBF increased compared to CBF; however, CBF showed better tensile strength compared to KBF. Both KBF and CBF loaded with nanoparticles exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli. However, KBF performed better compared to CBF. Antimicrobial effect of nanoparticles delayed the degradation of the bio-nanocomposite films. The present study proposes that the whole seaweed (Kappaphycus alvarezii) can be used directly for multiple industrial applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The use of functional information of taxa is a promising approach to uncover the underlying mechanism of ecosystem functioning. We used biological trait analysis (BTA) to assess the functional response of subtidal macrobenthos with multiple stressors. Seventeen environmental variables from 42 stations of five coastal districts were assessed along the southeast coast of India. Dominant fauna was assigned into 20 categories belonging to six functional traits. Additionally, we used five ecological groups (EG) of AMBI as a covariable trait to validate functional traits and EG relationship. The trait composition in the communities showed significant variation between undisturbed and disturbed areas. RLQ/Fourth corner combined approach illustrated the effects of stressors and isolated the corresponding species associated with different stressors. Smaller, short-lived, deposit-feeding, and discretely motile fauna occurred at the disturbed areas, whereas, larger, long-lived, and highly motile at the undisturbed area. Dissolved oxygen, organic enrichment, and metals concentration were the main environmental descriptors influencing the trait composition. The results highlight the importance of the BTA approach to uncover the response of the macrobenthic community to anthropogenic disturbances-driven impacts in multi-stressed near-shore coastal ecosystems., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Perna viridis Linnaeus (1758) is a major foulant in the cooling water systems of electric power stations located on the East coast of India. Though chlorination is considered an effective fouling control measure, the strategy may fail in the case of bivalve mussels, due to the ability of the mussels to close their shells and still survive for extended periods of time. In a given power station, continuous low dose (exomotive) chlorination (0.2 ± 0.1 mg l -1 ) is practiced to control biofouling. Laboratory experiments were carried out to assess the mortality and valve movement response of Perna viridis exposed to chlorine, using a Mosselmonitor ® . All size groups tested showed progressive reduction in valve opening upon chlorination. However, continuous dosing of chlorine concentration as high as 1.0 mg l -1 was required for sustained and complete valve closure response in this mussel. At lower concentration (0.7 mg l -1 ), the mussels were able to open their shells and feed. Sustained valve closure resulted in physiological stress to the mussels due to reduced feeding, subsequently leading to death. Time to 100% mortality was dependent on the size of the mussels. At 1.0 mg l -1 chlorine residual, smaller size group (30-50 mm) mussels showed 100% mortality in 79.3 h, while larger groups (50-70 mm and 70-90 mm) took 152 h and 243 h, respectively. Frequency of valve opening was high in smaller size group mussels (30-50 mm), compared with larger groups (70-90 mm). Even though the time taken for killing was size-dependent, frequency of valve opening and time period between successive openings were found to be characteristic of individual mussels. The observations provide new insight into the response of bivalve mussels to continuous chlorination in the context of biofouling control and point to the need to adopt pragmatic strategies to prevent mussel spat settlement rather than killing of adult mussels, thereby reducing environmental burden due to chlorine residuals. Usage of target-specific biocidal strategies (intermittent/pulse dosing) or alternative biocides (chlorine dioxide) may help mitigate green mussel fouling in tropical cooling water systems.

A combination of biotic indices, geo-accumulation (I geo ) index, and a multivariate approach were applied to assess the anthropogenic influence on the benthic community at five stations from 2018 to 2019 in the Swarnamukhi river estuary, Nellore, India. Non-metric multidimensional scaling and cluster analysis indicated that the Buckingham canal (BC) station showed azoic conditions and formed a separate cluster. Strong positive factor loadings of Cd (0.96), Al (0.93), Zn (0.91), Fe (0.90), Co (0.89), Cu (0.89), Ni (0.87), Pb (0.85), Cr (0.77), organic matter (0.94), Silt (0.92), and clay (0.93) and negative loading of sand (-0.90) showed the variability in sediment. AMBI results illustrated the disturbance status of each station and classified BC station as 'extremely disturbed' class, and M-AMBI assessed the ecological status as 'bad'. The I geo index also revealed metal (Cd) contamination. The present study illustrated that the combined approach is effective for ecological assessment of coastal ecosystem., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

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, GCMS 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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Phytoplankton entrained into cooling water systems of coastal power stations are subjected to acute chemical stress due to biocides (chlorine) used for biofouling control. They are subsequently released into the environment, where they may survive/recover or succumb. Experiments were conducted to evaluate the susceptibility of a centric (Chaetoceros lorenzianus) and pennate (Navicula sp.) diatom to in-plant administered concentrations of chlorine (0.2-0.5mg/L, TRO). Viability of cells exposed to chlorine was assessed by SYTOX® Green fluorimetry and was compared with other conventional end points like total cell counts, chlorophyll a content and cellular autofluorescence. Results showed a concentration-dependant reduction in viability, chlorophyll a and autofluorescence. C. lorenzianus cells were more susceptible to chlorine compared to Navicula sp. SYTOX® Green staining appears to be a sensitive method to assess chlorine-induced damages. The data show that in-use levels of chlorination can potentially impact entrained organisms; however, they can recover when returned to coastal waters., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Chlorine dioxide (ClO 2 ) is seen as an effective alternative to chlorine, which is widely used as an antifouling biocide. However, data on its efficacy against marine macrofoulants is scanty. In this study, acute toxicity of ClO 2 to larval forms of the fouling barnacle Amphibalanus reticulatus was investigated. ClO 2 treatment at 0.1mg/L for 20min elicited 45-63% reduction in naupliar metamorphosis, 70% inhibition of cyprid settlement and 80% inhibition of metamorphosis to juveniles. Increase in concentration to 0.2mg/L did not result in any significant difference in the settlement inhibition or metamorphosis. Treatment with 0.2mg/L of ClO 2 elicited substantial reduction in the settlement of barnacle larvae compared to control. The study indicates the possibility of using ClO 2 as an alternative antifouling biocide in power plant cooling water systems. However, more work needs to be done on the environmental effects of such switchover, which we are currently undertaking., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Efforts to generate a vaccine to prevent infection by human immunodeficiency virus (HIV) have focused on inducing neutralizing antibodies. However, cytotoxic T-lymphocyte (CTL) responses are a major immune defense mechanism required for recovery from many different virus infections. Since CTL epitopes can be defined by short synthetic peptides, we searched for HIV peptides that elicit a viral-specific CTL response in mice. We have developed a new method for screening CTL-inducing peptides involving a single injection into the footpad of mice to prime CTLs in the draining popliteal lymph node of mice within 10 days. Our results demonstrate that a 15-amino acid peptide (aa 315-329) derived from the V3 loop of HIV gp120 caused a rapid induction of peptide-specific and gp160-specific CD8-positive CTLs. Lysis of targets is specific since cells preincubated with unrelated peptides are resistant to lysis as are cells of a different MHC haplotype pretreated with the cognate peptide. Pretreatment of restimulated node cells with complement plus anti-CD8 but not anti-CD4 removed the lytic activity. We also successfully induced in vivo CTL activity with unmodified synthetic peptides from the influenza and Sendai virus nucleoproteins, indicating general applicability of our method for rapid screening of CTL epitopes. Because HIV replication has been reported by several labs to occur mainly in lymph nodes of infected patients, the rapid induction of HIV-specific CTLs in proximal lymph nodes by unmodified peptides emphasizes the physiological significance of our findings toward vaccine and therapeutic approaches.