Sathappan Shanthi

Plectranthus amboinicus leaf extract mediated synthesis of zinc oxide nanoparticles and its control of methicillin resistant Staphylococcus aureus biofilm and blood sucking mosquito larvae.

In this study, zinc oxide nanoparticles were biologically synthesized using the leaf extract of Plectranthus amboinicus (Pam-ZnO NPs). The synthesized Pam-ZnO NPs were characterized by UV-Vis spectrophotometer, FTIR, TEM and XRD analysis. TEM analysis of Pam-ZnO NPs showed the average size of about 20-50 nm. Pam-ZnO NPs control the growth of methicillin-resistant Staphylococcus aureus biofilms (MRSA ATCC 33591) at the concentration of 8-10 μg/ml. Confocal laser scanning microscope (CLSM) images revealed that Pam-ZnO NPs strongly inhibited the biofilm forming ability of S. aureus. In addition, Pam-ZnO NPs showed 100% mortality of fourth instar mosquito larvae of Anopheles stephensi, Culex quinquefasciatus and Culex tritaeniorhynchus at the concentration of 8 and 10 μg/ml. The histopathological studies of Pam-ZnO NPs treated A. stephensi and C. quinquefasciatus larvae revealed the presence of damaged cells and tissues in the mid-gut. The damaged tissues suffered major changes including rupture and disintegration of epithelial layer and cellular vacuolization. The present study conclude that Pam-ZnO NPs showed effective control of S. aureus biofilms and mosquito larvae by damaging the mid gut cells.

Antibacterial, antibiofilm and cytotoxic effects of Nigella sativa essential oil coated gold nanoparticles

This study reports the biological synthesis of gold nanoparticles using essential oil of Nigella sativa (NsEO-AuNPs). The synthesized NsEO-AuNPs were characterized by UV-visible spectra, X-ray diffraction (XRD), FTIR and Transmission electron microscopy (TEM). UV-vis spectra of NsEO-AuNPs showed strong absorption peak at 540 nm. The X-ray diffraction analysis revealed crystalline nature of nanoparticle with distinctive facets (111, 200, 220 and 311 planes) of NsEO-AuNPs. The FTIR spectra recorded peaks at 3388, 2842, 1685, 1607, 1391 and 1018 cm(-1). TEM studies showed the spherical shape of nanoparticles and the particle size ranges between 15.6 and 28.4 nm. The antibacterial activity of NsEO-AuNPs was greater against Gram positive Staphylococcus aureus MTCC 9542 (16 mm) than Gram negative Vibrio harveyi MTCC 7771 (5 mm) at the concentration of 10 μg ml(-1). NsEO-AuNPs effectively inhibited the biofilm formation of S. aureus and V. harveyi by decreasing the hydrophobicity index (78% and 46% respectively). The in-vitro anti-lung cancer activity confirmed by MTT assay on the cell line of A549 carcinoma cells showed IC50 values of bulk Au at 87.2 μg ml(-1), N. sativa essential oil at 64.15 μg ml(-1) and NsEO-AuNPs at 28.37 μg ml(-1). The IC50 value showed that NsEO-AuNPs was highly effective in inhibiting the A549 lung cancer cells compared to bulk Au and N. sativa essential oil.

Biosynthesis of silver nanoparticles using a probiotic Bacillus licheniformis Dahb1 and their antibiofilm activity and toxicity effects in Ceriodaphnia cornuta.

In the present study, we synthesized and characterized a probiotic Bacillus licheniformis cell free extract (BLCFE) coated silver nanoparticles (BLCFE-AgNPs). These BLCFE-AgNPs were characterized by UV-visible spectrophotometer, XRD, EDX, FTIR, TEM and AFM. A strong surface plasmon resonance centered at 422 nm in UV-visible spectrum indicates the formation of AgNPs. The XRD spectrum of silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal. TEM and AFM showed the AgNPs were spherical in shape within the range of 18.69-63.42 nm and the presence of silver was confirmed by EDX analysis. Light and Confocal Laser Scanning Microscope (CLSM) images showed a weak adherence and disintegrated biofilm formation of Vibrio parahaemolyticus Dav1 treated with BLCFE-AgNPs compared to control. This result suggests that BLCFE-AgNps may be used for the control of biofilm forming bacterial populations in the biomedical field. In addition, acute toxicity results concluded that BLCFE-AgNPs were less toxic to the fresh water crustacean Ceriodaphnia cornuta (50 μg/ml) when compared to AgNO3 (22 μg/ml). This study also reports a short term analysis (24 h) of uptake and depuration of BLCFE-AgNPs in C. cornuta.

GFP tagged Vibrio parahaemolyticus Dahv2 infection and the protective effects of the probiotic Bacillus licheniformis Dahb1 on the growth, immune and antioxidant responses in Pangasius hypophthalmus

In this study, the pathogenicity of GFP tagged Vibrio parahaemolyticus Dahv2 and the protective effect of the probiotic strain, Bacillus licheniformis Dahb1 was studied on the Asian catfish, Pangasius hypophthalmus. The experiment was carried out for 24 days with three groups and one group served as the control (without treatment). In the first group, P. hypophthalmus was orally infected with 1 mL of GFP tagged V. parahaemolyticus Dahv2 at two different doses (10(5) and 10(7) cfu mL(-1)). In the second group, P. hypophthalmus was orally administrated with 1 ml of the probiotic B. licheniformis Dahb1 at two different doses (10(5) and 10(7) cfu mL(-1)). In the third group, P. hypophthalmus was orally infected first with 1 mL of GFP tagged V. parahaemolyticus Dahv2 followed by the administration of 1 mL of B. licheniformis Dahb1 (combined treatment) at two different doses (10(5) and 10(7) cfu mL(-1)). The growth, immune (myeloperoxidase, respiratory burst, natural complement haemolytic and lysozyme activity) and antioxidant (glutathione-S-transferase, reduced glutathione and total glutathione) responses of P. hypophthalmus were reduced after post infection of GFP tagged V. parahaemolyticus Dahv2 compared to control. However, after administration with the probiotic B. licheniformis Dahb1 at 10(5) cfu mL(-1), P. hypophthalmus showed significant increase in the growth, immune and antioxidant responses compared to 10(7) cfu mL(-1). On the otherhand, the growth, immune and antioxidant responses of P. hypophthalmus infected and administrated with combined GFP tagged Vibrio + Bacillus at 10(5) cfu mL(-1) were relatively higher than that of GFP tagged V. parahaemolyticus Dahv2 and control groups but lower than that of probiotic B. licheniformis Dahb1 groups. The results of the present study conclude that the probiotic B. licheniformis Dahb1 at 10(5) cfu mL(-1) has the potential to protect the P. hypophthalmus against V. parahaemolyticus Dahv2 infection by enhancing the growth, immune and antioxidant responses. The probiotic B. licheniformis Dahb1 would be effectively used in the treatment of aquatic diseases for improvement of aquaculture industry.

A novel clip domain serine proteinase (SPs) gene from the haemocytes of Indian white shrimp Fenneropenaeus indicus: molecular cloning, characterization and expression analysis.

The Indian white shrimp, Fenneropenaeus indicus (formerly Penaeus indicus), is one of the major commercial shrimp species of the world. It is reported in the Indo-West Pacific from eastern and south-eastern Africa, through Malaysia and Indonesia to southern China and northern Australia [1,2]. The defense mechanism in F. indicus is poorly understood, but knowledge of this is a prerequisite for the development of intervention strategies to control diseases in Indianwhite shrimp culture. The immune related genes in arthropods have been discovered and characterized during the past few years and shown to participate in immunological processes. The proPO system plays an important role in the immune responses of invertebrates [3] and activated by an endogenous activating system and exogenous materials/agents such as lipids, detergents, organic solvents, and microbial elicitors like b-1, 3-glucan, lipopolysaccharide (LPS), and peptidoglycan (PG) [4e7]. The inactive proPO zymogen is converted to the active phenoloxidase (PO), by a clip domain serine proteinase (SPs) designated as a proPO activating enzyme (PPAE) [3,8]. The proPO cascade involves several proteolytic steps which are catalyzed by multiple SPs [9e13]. The terminal clip domain SP (PPAE) that

Green Synthesized Silver Nanoparticles: Toxicity Against Poecilia reticulata Fishes and Ceriodaphnia cornuta Crustaceans

Recently, the green synthesis of silver nanoparticles gained increasing attention due to interesting properties for optical, antimicrobial and pest control applications. However, their toxicity against micro-crustaceans and fishes has been scarcely explored, while most of the research efforts focused on mosquito control with the green-synthesized nanocomposites. In this study, we investigated the toxic effects of AgNO3, Cissus quadrangularis (Cq)-synthesized AgNPs and Cq extract in two different study models, the larvae of Poecilia reticulata fishes and adults of the micro-crustacean Ceriodaphnia cornuta. In both species, AgNO3 and Cq-AgNPs showed high mortality rates even if tested at very low doses. Molecular analysis revealed high DNA damages induced by Cq-AgNPs on both aquatic organisms. Furthermore, light microscopy studies evidenced lesions in the gills and vacuolization in the gills and in the abdomen of P. reticulata larvae. Overall, our research pointed out that the exposure of aquatic organisms to AgNO3 or green-fabricated AgNPs can damage fishes and crustaceans, posing noteworthy risks to the aquatic ecosystems.

Growth inhibition and antibiofilm potential of Ag nanoparticles coated with lectin, an arthropod immune molecule

Lectins from the haemolymph of arthropods, including crustaceans, are molecules potentially involved in the immune recognition and phagocytosis. Here, lectin was purified from the haemolymph of blue swimmer crab Portunus pelagicus, using mannose-coupled sepharose CL-4B affinity column chromatography. In SDS-PAGE analysis, lectin showed a molecular mass of approximately 155kDa. The synthesis of lectin-coated silver nanoparticles (lectin-coated AgNPs) was confirmed by UV-Vis spectroscopy, XRD, FTIR, SEM, TEM, SAED, and EDX analysis. TEM analysis revealed that lectin-coated AgNPs were spherical in shape with size of 30-57nm. Their antibacterial activity against human pathogenic Gram negative and Gram-positive bacteria was determined by agar well diffusion method. Lectin-coated AgNPs showed significant antimicrobial activity when compared to lectin and silver nitrate tested alone. The antibiofilm properties of lectin-coated AgNPs were also investigated on human pathogenic Gram-negative Proteus vulgaris, Pseudomonas aeruginosa and Gram-positive Enterococcus faecalis and Bacillus pumilus. Lectin-coated AgNPs showed antibiofilm activity on the bacteria as well as on Candida albicans. Lectin-coated AgNPs reduced the biofilm architecture interfering with cell adhesion and polysaccharide matrix. This was additionally confirmed by exopolysaccharide (EPS) quantification index revealing the trouble in the structural reliability of biofilm by decrease in EPS and bacterial adhesion to hydrocarbons.

Molecular Cloning of Peroxinectin Gene and Its Expression in Response to Peptidoglycan and Vibrio Harveyi in Indian White Shrimp Fenneropenaeus Indicus

Abstract The cDNA sequence of peroxinectin was obtained from the haemocytes of Indian white shrimp Fenneropenaeus indicus using RT-PCR and RACE. Fenneropenaeus indicus peroxinectin (Fi-Pxn) sequence has an open reading frame (ORF) of 2415 bp encoding a protein of 804 amino acids with 21 residues signal sequence. The mature protein has molecular mass of 89.8 kDa with an estimated pI of 8.6. Two putative integrin-binding motifs, RGD and KGD, were observed at the basic N-terminal and C-terminal part of the mature aminoacid sequence. Fi-Pxn nucleotide sequence comparison showed high homology to mud crab Scylla serrata (89%) and to various vertebrate and invertebrate species. qRT-PCR showed peroxinectin mRNA transcript in haemocytes of F. indicus increased at 6 h post injection of peptidoglycan and Vibrio harveyi. The Fi-Pxn was mainly expressed in the tissues of haemocytes and the heart. The moulting stage responses showed Fi-Pxn expression in premoult stages D0/1 and D0/2.