Santhiyagu Prakash

Antifouling and toxic properties of the bioactive metabolites from the seagrasses Syringodium isoetifolium and Cymodocea serrulata

The present study documents the antifouling and toxic properties of seagrasses Syringodium isoetifolium and Cymodocea serrulata. For that, the seagrasses S. isoetifolium and C. serrulata were extracted individually using organic solvents viz. dichloromethane, acetone and methanol. Amongst the extracts, the maximum antimicrofouling and antimacrofouling activities were exhibited by methanol extracts of both the seagrasses. The Minimal Inhibitory Concentration (MIC) of methanolic extracts of seagrasses was ranged from 1.0 to 10µg/ml against test biofilm bacteria and microalgal strains. Similarly, 100% fouling inhibition of limpet Patella vulgata was found at 6.0mg/ml of methanolic extracts of seagrasses. The mussel Perna indica showed 50% of byssal production and attachment inhibition at 21.51±2.03, 17.82±1.07µg/ml and the anticrustaecean activity for 50% mortality of Artemia salina was recorded at 732.14±9.21 and 394.16±5.16µg/ml respectively for methanolic extracts of S. isoetifolium and C. serrulata. The minimal inhibitory and higher lethal concentrations of active methanol extracts shows it׳s less toxic nature. Based on the prolific results, methanol extracts of S. isoetifolium and C. serrulata were subjected to purification using silica gel column and thin layer chromatography. Then the active compounds of the bioassay guided fractions were partially characterized using gas chromatography coupled with mass spectroscopy (GC-MS) and keyed out that fatty acids (C16 to C24) were the major components which responsible for the antifouling properties of the candidate seagrasses.

Optimization of bacteriocin production by Lactobacillus sp. MSU3IR against shrimp bacterial pathogens

BackgroundAquaculture is one amongst the growing and major food producing sectors. Shrimp culture is one of the subsectors of aquaculture that attracts more attention because of the economic interest. However, the shrimp culture systems have been facing severe consequences and economical losses due to disease outbreaks. Risk of disease outbreak can be combated with the application of probiotics. For economically viable production of such probiotic products, the present study provides information on the optimization and partial purification of bacteriocin produced by a goat milk isolate Lactobacillus sp. MSU3IR against the shrimp bacterial pathogens.ResultsBacteriocin production was estimated as a measure of bactericidal activity (arbitrary Unit/ml) over the test strains. The optimum culture conditions and media components for maximum bacteriocin production by Lactobacillus sp. MSU3IR were: pH: 5.0, temperature: 30°C, carbon source: lactose; nitrogen source: ammonium acetate; NaCl: 3.0% and surfactant: Tween 80. MRS medium was found to extend better bacteriocin production than other tested media. Upon partial purification of bacteriocin, the SDS-PAGE analysis had manifested the presence of two peptide bands with the molecular weight of 39.26 and 6.38 kDa, respectively.ConclusionThe present results provide baseline trend for the statistical optimization, scale up process and efficient production of bacteriocin by the candidate bacterial strain Lactobacillus sp. MSU3IR which could be used to replace the usage of conventional chemotherapeutics in shrimp culture systems.

Antifouling activity of the methanolic extract of Syringodium isoetifolium, and its toxicity relative to tributyltin on the ovarian development of brown mussel Perna indica

The present study evaluated reproductive toxicity and antifouling activity of methanolic extract of seagrass Syringodium isoetifolium (25 μg/ml) relative to the conventional antifoulant, tributyltin (TBT; 100 ng/l) on the ovarian development of the brown mussel Perna indica. Gonado Somatic Index (GSI) and Digestive Gland Index (DGI) of TBT exposed mussels decreased in comparison with mussels exposed to S. isoetifolium extract. Interestingly, mussels treated with S. isoetifolium showed normal cellular architecture in gills, digestive gland, muscle and ovary. However, TBT increased interfilamental space and fusion of the filaments in gills, disruption in the digestive tubules and reduction in basement membrane thickness. Besides in adductor muscle, TBT induced muscle degeneration, and necrotic muscle layer. In ovary, TBT inflicted the fusion of developing oocytes. TBT had significantly retarded the ovarian development and substantially affected the biochemical constituents leading to an impairment of oogenesis as against the null effects noticed from the S. isoetifolium extract treated mussels. On the ground of eco-friendly properties, the seagrass S. isoetifolium could be used as a source for the production of green antifoulant.

Environmentally benign antifouling potentials of triterpene-glycosides from Streptomyces fradiae: a mangrove isolate

In the present study, an attempt has been made to screen and evaluate the antifouling potentials of the actinobacterial strain Streptomyces fradiae RMS-MSU isolated from the manakkudy mangroves of Tamilnadu. Screening results showed that the ethyl acetate extract of S. fradiae RMS-MSU displayed a wide spectrum of antagonistic activity (10 to 21 mm) against marine biofilm bacterial strains with least minimal inhibitory concentrations (MIC) and maximum bactericidal concentrations (MBC). The extract showed promising antimicroalgal activity with MIC values ranging between 100 and 400 μg mL−1. The anti-crustacean activity for 50% mortality (LC50) of Artemia salina was recorded as 273.77 μg mL−1. An EC50 value of 77.03 μg mL−1 for the 50% inhibition of byssus production and attachment of mussel Perna indica was observed. The crude extract of S. fradiae RMS-MSU showed an LC50 value of 718.79 μg mL−1 for 50% mortality of mussel. A therapeutic ratio (LC50/EC50) of 9.33 indicated the nontoxic nature of the extract. The mollusc foot adherence assay using the limpet Patella vulgata showed 6.66% fouling and 92.96% regaining at 7 mg mL−1 after transfer to fresh seawater.

In vitro-Scientific evaluation on antimicrobial, antioxidant, cytotoxic properties and phytochemical constituents of traditional coastal medicinal plants.

In the present study, evaluation of antimicrobial, antioxidant, phytochemical constituents and toxicological properties of six coastal medicinal plants (CMPs) such as Ipomea biloba, Cantharanthus roseus, Cymbopogon citratus, Vitex negundo, Thespesia populnea and Pandanus tectorius was done. The maximum antimicrobial activity was recorded by methanolic extracts of V. negundo and T. populnea against bacterial and fungal pathogens. Similarly, methanolic extracts of V. negundo and T. populnea evidenced highest antioxidant properties. The extract of T. populnea showed the maximum cytotoxicity against Artemia salina with the LC50 value of 478.11μg/ml. The hemolytic property of CMPs extracts was V. negundo (8.91%), T. populnea (21%) and C. citratus (64%) also the hemolytic index did not show any hemolysis of human erythrocytes. Furthermore, the TLC separation of V. negundo and T. populnea extracts exhibited the presence of Flavonoids (Rf-0.74) and Terpenoids (Rf-0.64). The present findings propose the promising clinical applications of selected CMPs.

Isolation, Screening and Evaluation of Antifouling Activity of Mangrove Associated Bacterium, Bacillus subtilis subsp. subtilis RG

In the present study, an attempt has been made to explore the antifouling activity of bacterial strains isolated from the root and rhizosphere soil of Pichavaram mangroves, India. Altogether, 14 different mangrove associated bacterial strains (MAB1–14) were isolated and screened for antagonistic activity against fouling bacterial strains. Screening results inferred that, five (35.71xa0%) out of 14 MAB isolates exhibited antagonistic activity. Among them, MAB6 showed notable growth inhibitory activity and it was identified as Bacillus subtilis subsp. subtilis through 16S rRNA gene sequencing. The crude ethyl acetate extract of B. subtilis subsp. subtilis RG strongly inhibited (8–13xa0mm) the growth of fouling bacterial strains. Minimum inhibitory concentration (MIC) of extract against fouling bacterial strains was ranged between 25 and 50xa0µg/ml; whilst minimum bactericidal concentration was ranged from 50 to 100xa0µg/ml, respectively. This extract has also effectively inhibited the growth of fouling microalgal strains with the MIC range of 50–100xa0µg/ml, respectively. Anticrustacean assay using Artemia franciscana larvae showed the LC50 value of 264.89xa0µg/ml. Further, the lower EC50 value (63.46xa0µg/ml) than the LC50 value (156.32xa0µg/ml) and 100xa0% recovery of mussel Perna indica in toxicity assay inferred the non-toxic nature of the extract.

Influence of physicochemical and nutritional factors on bacterial diversity in mangrove sediments along the southwest coast of Tamilnadu, India

The present study was undertaken to investigate the diversity of mangrove-associated bacterial genera at Manakudy estuary, Southwest coast of India. The root and rhizosphere sediments of both mangrove and their associated plants were collected from chosen area. Results inferred that the maximum nutrients, THB density, and diversity indices were recorded in rhizosphere and root sample of Avicennia officinalis. Altogether, 258 bacterial strains were isolated from the chosen mangrove samples and screened for nitrogen fixing and phosphate solubilizing ability. Screened result inferred that, 36.43 % isolates had nitrogen fixing and 29.45 % isolates had phosphate solubilizing ability. Here, the genus Bacillus spp. (21.71xa0%) was the most dominant genera. The bacterial diversity indices, i.e., univariate analysis showed remarkable variation between the chosen samples; however, maximum diversity indices was registered by rhizosphere and root sample of A. officinalis. The 95xa0% confidence interval and ellipse showed that samples were well mendacious within AvTD and VarTD. Likewise, the multivariate analysis like similarity percentage was good discriminator from 16.64 to 100xa0% by Bray–Curtis dissimilarity. The prinicipal component analysis (PCA) showed marked variation between the tested bacterial communities. Cluster analysis and non-metric multi-dimensional scaling (MDS) were grouped by Bray–Curtis similarity index which strongly evidence that the rhizosphere and root samples of A. officinalis were highly diversified in the study area.

Spermicidal activity of Indian seaweeds: an in vitro study.

Contraceptive properties of seaweeds are still stands as lacuna; in this context, the screening of in vitro male contraceptive properties of crude ethanolic extract of Indian seaweeds against normal human sperm is carried out. In total, twelve seaweeds were screened for in vitro spermicidal activity. Among these twelve seaweeds, Halimeda gracilis showed 100% inhibition of human spermatozoa at 10 mg ml−1 concentration in 20 s and its EC50 value was 2.05 mg ml−1 in 20 s. Further, dose‐ and time‐dependent spermicidal assay revealed that the sperm was completely immobilised for 20 s. Plasma membrane of sperm was damaged due to the exposure of H. gracilis extract. MTT assay with H. gracilis extract showed 88.5% of cytotoxic incidence. H. gracilis extract tested for cytotoxicity against Artemia salina recorded LC50 value of 34.8 μg ml−1. Phytochemical analysis of H. gracilis extract evidenced the presence of alkaloids, flavonoids, proteins and sugars. Results of this study clearly inferred that the synergistic effect of active principles reside within the H. gracilis extract had shown better contraceptive activity.

Environmentally benign antifouling activity and toxic properties of bioactive metabolites from mangrove Excoecaria agallocha L

AbstractThis 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 >xa01 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 (>xa085%) 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.n Graphical abstract