Grasian Immanuel

The present study was undertaken to biosynthesize zinc oxide nanoparticles (ZnONPs) using a mangrove-associated actinobacterium Streptomyces olivaceus (MSU3) under in vitro conditions. The synthesized ZnONPs were structurally characterized through UV, FT-IR, TG–DTA, XRD, SEM and EDX analysis. Analysis of biosynthesized ZnONPs in UV–Vis spectroscopy showed presence of functional groups between the wavelengths 325 and 380 nm. FT-IR analysis showed the functional groups, such as halo bromide (C–Br), alkyne (C≡C), carboxylic acid (O–H), nitro (N–O), fluoro (C–F), alkene (C=C) and aromatic (R–C–H) groups, respectively, within the wave numbers between 614.30 and 3074.41 cm⁻¹. The crystalline poly-dispersed quasi spherical nature of ZnONPs expressed the average particle size of 37.9 nm with the 2θ values of 11.802–37.885°. Antibacterial activity of ZnONPs showed pronounced inhibitory zone (25 mm) and least MIC and MBC values (125 and 250 µg ml⁻¹) against Escherchia sp. In the antifouling study, ZnONPs strongly inhibited byssal thread formation in mussel Perna indica and recorded LC₅₀ value of 424.47 µg ml⁻¹. Mollusc foot adherence assay inferred that the ZnONPs effectively inhibited settlement of limpet Patella vulgata and showed minimal fouling (26.43%) at 350 µg ml⁻¹ and recorded LC₅₀ value of 218.77 µg ml⁻¹. Results of anticrustacean assay depicted that, ZnONPs had registered LC₅₀ value of 676.08 µg ml⁻¹ against Artemia salina nauplii. From this study, it could be concluded that an eco-friendly approach could be used to open a new avenue for biosynthesis of ZnONPs from a mangrove associated actinobacterium S. olivaceus (MSU3) in antifouling studies.

The present study was undertaken to compare the in vitro antioxidant properties of marine trash fish Odonus niger liver oil and commercially available cod liver oil. For this O. niger fishes were collected and the oil was extracted from the liver mass by following Bligh and Dyer method and it was purified. Further the antioxidant potential of various concentrations (12.5 to 200µg/ml) of the extracted oil was performed through different standard antioxidant assays, simultaneously the same concentrations of commercial cod liver oil were also performed. The antioxidant potential of both oils was compared with appropriate standards like ascorbic acid, gallic acid and quercetin in the respective assays. The different assays performed were hydroxyl radical scavenging activity (23.24%), total antioxidant activity (43.06%), DPPH radical scavenging activity (60.06%), reducing power effect (68.22%), lipid peroxidation inhibitory activity (53.10%) and ferrous ions chelating activity (75%) respectively for O. niger at the highest concentration of 200μg/ml. All the above activities showed that O. niger liver oil possessed better antioxidant potential, especially at higher concentration (200 µg/ml) than the tested commercial cod liver oil.

Bio-surfactants are a principal group of significant molecules obtained from the microbial sources expressed with distinctive characteristics like biodegradation of hydrocarbons and also have different biomedical properties. The present investigation aims to assess the biomedical properties of synthesized bio-surfactant, rhamnolipid from Pseudomonas aeruginosa (DKB1) under in vitro conditions. The candidate bacterium P. aeruginosa (DKB1) was isolated from oil-polluted fishing harbors of Kanyakumari coast. Initially, the bio-surfactant production by this candidate strain was confirmed by oil displacement assay, hemolytic assay, drop collapse assay and emulsification index. Further, the production of bio-surfactant was achieved through submerged fermentation process using Bushnell–Haas mineral salts medium supplemented with 2% olive oil. The yield of the bio-surfactant was attained as 2.4 g/l and confirmed as rhamnolipid through blue agar plate assay; further, the extracted rhamnolipid was purified and characterized through standard procedures. In stability studies, the rhamnolipid could withstand up to pH 12, temperature 100 °C and 15% of NaCl concentration. The biomedical application of rhamnolipid (30 μg ml⁻¹) was determined by antibacterial, antioxidant and cytotoxic studies. It exhibited a maximum growth inhibition against Bacillus subtilis (26 mm) with the MIC value of 8 μg ml⁻¹. In antioxidant test, rhamnolipid expressed significant (P < 0.0001) inhibition of total reducing power (44.11%), DPPH activity (61.60%), hydroxyl radical (83.30%) and nitric oxide (51.86%) scavenging ability at 100 μg ml⁻¹with the respective IC50 values of 130.50, 77.18, 52.08 and 95.43 μg ml⁻¹. The anticancer activity of the rhamnolipid was assessed with the help of MTT test against MCF-7, HT-29 and E-143 cancer cell lines individually, and the viability of the cells was observed, respectively, as 10.24, 17.66 and 13.50% at 250 μg ml⁻¹concentration with the respective IC50 values of 140.2, 81.02 and 138.9 μg ml⁻¹. From the results, it could be concluded that the rhamnolipid produced by P. aeruginosa (DKB1) isolated from oil-polluted area has effective biomedical properties.

This study was aimed to investigate the antifouling (AF) potentials and toxic properties of methanol extract from leaves of mangrove Excoecaria agallocha. Antimicrofouling activity results inferred that this extract strongly inhibited fouling bacterial and microalgal growth. This extract had also inhibited the settlement of brown mussel Perna indica and larvae of barnacle Balanus amphitrite. Further, EC₅₀ < LC₅₀ and therapeutic ratio > 1 together propagated non-toxic nature of the extract. Mollusk foot adherence assay result showed complete inhibition of foot spreading and loss of attachment of common rocky fouler Patella vulgata to the substrata. Field assay results affirmed that this extract effectively deterred settlement of biofoulers. Purification and GC-MS analysis of bioassay-guided active spot evidenced presence of three major compounds (> 85%) responsible for the promising AF activity. The identified lead compounds subjected to an estimation (BIOWIN™) program developed by United States Environmental Protection Agency (USEPA) predicts that they are biodegradable in nature.

In the present investigation, an actinobacterial strain of Streptomyces olivaceus (MSU3) was isolated from a rhizosphere sediment sample of a mangrove environment, and it was confirmed through 16S rRNA sequencing. The isolated strain saccharified various agro-residues such as vegetable, banana, mango peel, sugarcane bagasse and sugarcane juice, followed by bioethanol production. Among the tested residues, the actinobacterial strain exhibited the maximum percentage of saccharification and bioethanol production in sugarcane juice-substituted medium at the optimized culture conditions of pH 6, temperature 30°C, innoculum size 2.5% and incubation time 72 h, substituted with 2.5% dextrose and 2.0% urea, respectively, as carbon and nitrogen sources. The concentration of produced bioethanol was estimated through high-performance liquid chromatography (HPLC) and it was exhibited as 76% with the retention time of 2.055 min and percentage area of 135694.91μV/sec. In Fourier transmission infrared (FT-IR) analysis, six functional groups (O-H, C-O, C=O, C=C, -C=C and C-Br) from the produced bioethanol were denoted between the wavenumber of 3264.27 and 551.35 cm⁻¹. Finally, the Gaschromatography-Massspectrphotometry (GC-MS) analysis confirmed that the functional group similar to bioethanol was detected in the chromatogram with a retention time of 2.50 as well as 13.87 min. Based on the results, it could be confirmed that the actinobacterial isolate is a potent strain and can also be used to hydrolyze agro-residues and to convert the agro-residues into economically important byproducts like bioethanol.