Synthesis of biocomposites from microalgal peptide incorporated polycaprolactone/ κ- carrageenan nanofibers and their antibacterial and wound healing property.

Antimicrobial peptides (AMPs) are promising novel agents for targeting a wide range of pathogens. In this study, microalgal peptides derived from native microalgae were incorporated into polycaprolactone (PCL) with ƙ-Carrageenan (ƙ-C) forming nanofibers using the electrospinning method. The peptides incorporated in the nanofibers were characterized by fourier infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), and contact angle measurement. The results showed that peptides with molecular weights < 10 kDa, when loaded into nanofibers, exhibited lower wettability. The SEM analysis revealed a thin, smooth, interconnected bead-like structures. The antimicrobial activity of the electrospun nanofibers was evaluated through disc diffusion, and minimum inhibitory activity against Escherichia coli (MTTC 443), and Staphylococcus aureus (MTTC 96), resulting in zones of inhibition of 24 ± 0.5 mm and 14 ± 0.5 mm, respectively. The in vitro biocompatibility of the synthesized nanofibers was confirmed using in HEK 293 cell lines with an increased cell viability. Interestingly, the fibers also exhibited a significant wound-healing properties when used in vitro scratch assays. In conclusion, algal peptides incorporated with PCL/ ƙ-C were found to exhibit antimicrobial and biocompatible biomaterials for wound healing applications.

Production, optimization and characterization of partially purified anti-mycotic compound from marine soil derived streptomycetes originating at unexplored region of Bay of Bengal, India.

Sixty-eight morphologically distinct isolates of marine actinomycetes were derived from seashore, mangrove, and saltpan ecosystems located between the Palk Strait and Gulf of Mannar region, Bay of Bengal, Tamilnadu. Twenty-five (36.8%) isolates exhibited anti-mycotic activity against Candida albicans and Cryptococcus neoformans in preliminary screening, and 4 isolates with prominent activity were identified and designated at the genus level as Streptomyces sp. VPTS3-I, Streptomyces sp. VPTS3-2, Streptomyces sp. VPTSA1-4 and Streptomyces sp. VPTSA1-8. All the potential antagonistic isolates were further characterized with phenotypic and genotypic properties including 16S rRNA gene sequencing and identified species level as Streptomyces afghaniensis VPTS3-1, S. matensis VPTS3-2, S. tuirus VPTSA1-4 and S. griseus VPTSA1-8. In addition, the active fractions from the potential antagonistic streptomycetes were extracted with organic solvents by shake flask culture method and the anti-mycotic efficacies were evaluated. The optimization parameters for the production of the anti-mycotic compound were found to be pH between 7 and 8, the temperature at 30ᵒC, the salinity of 2%, incubation of 9 days, and starch and KNO3 as the suitable carbon and nitrogen sources respectively in starch casein medium.

Recent advances in remediation strategies for mitigating the impacts of emerging pollutants in water and ensuring environmental sustainability.

The proliferation of emerging pollutants (EPs), encompassing a range of substances such as phthalates, phenolics, pharmaceuticals, pesticides, personal care products, surfactants, and disinfection agents, has become a significant global concern due to their potential risks to the environment and human well-being. Over the past two decades, numerous research studies have investigated the presence of EPs in wastewater and aquatic ecosystems, with the United States Environmental Protection Agency (USEPA) categorizing these newly introduced chemical compounds as emerging contaminants due to their poorly understood impact. EPs have been linked to adverse health effects in humans, including genotoxic and cytotoxic effects, as well as conditions such as obesity, diabetes, cardiovascular disease, and reproductive abnormalities, often associated with their estrogenic action. Microalgae have shown promise in the detoxification of both inorganic and organic contaminants, and several large-scale microalgal systems for wastewater treatment have been developed. However, the progress of algal bioremediation can be influenced by accidental contaminations and operational challenges encountered in pilot-scale research. Microalgae employ various processes, such as bioadsorption, biouptake, and biodegradation, to effectively remediate EPs. During microalgal biodegradation, complex chemical compounds are transformed into simpler substances through catalytic metabolic degradation. Integrating algal bioremediation with existing treatment methodologies offers a viable approach for efficiently eliminating EPs from wastewater. This review focuses on the use of algal-based biological remediation processes for wastewater treatment, the environmental impacts of EPs, and the challenges associated with implementing algal bioremediation systems to effectively remove emerging pollutants.

Aquatic and human health risk assessment of Humanogenic Emerging Contaminants (HECs), Phthalate Esters from the Indian Rivers.

Phthalate esters (PEs) one of the widely used plasticizers, and are known for their environmental contamination and endocrine disruption. Hence, it is important to study their distribution in a riverine environment. This study was aimed to determine the Spatio-temporal trends of 16 PEs in surface water, sediment and fish from rivers in southern India, and to assess their environmental health risks. Phthalates were quantified in all matrices with the mean concentrations (∑16PEs) in water, sediment and fish as 35.6 µg/L, 1.25 µg/kg and 17.0 µg/kg, respectively. The Kaveri River is highly loaded with PEs compared to the Thamiraparani and Vellar Rivers. PEs such as DBP, DEHP, DCHP and DiBP were most frequently detected in all matrices, and at elevated concentrations in the dry season. The risk quotient (RQ < 1) suggests that the health risk of PEs from river water and fish to humans is negligible. However, DBP and DEHP from the Kaveri River pose some risk to aquatic organisms (HQ > 1). DEHP from the Vellar River may pose risks to algae and crustaceans. Non-priority phthalate (DiBP) may pose risks to Kaveri and Vellar River fish. The bioaccumulation factor of DCHP and DEHP was found to be very high in Sardinella longiceps and in Centropristis striata, and also exceeded the threshold limit of 5000 suggesting that PEs in the riverine environment may pose some health concerns. This is the first study to assess the spatio-temporal distribution, riverine flux and potential ecological effects of 16 PEs from the southern Indian Rivers.

Evaluation of microalgal strains and microalgal consortium for higher lipid productivity and rich fatty acid profile towards sustainable biodiesel production.

This present study has attempted to screen four microalgal strainsChlorella vulgaris, Coelastrellasp.Scenedesmus dimorphusandChlorococcumsp. and consortium for biodiesel application.Coelastrella sp. was found to show marginally higher optical density of 1.13 on 19th day whereas C. vulgaris and S. dimorphus consortium showed 1.59 OD. Regarding the dry cell weight, S. dimorphus and Chlorella vulgaris was found to yield higher DCW at about 0.544 and 0.508 g/L, respectively. In outdoor pond raceway pond, C. vulgaris and S. dimorphus yielded 0.76-0.80 g/L while consortium showed 0.87 g/L biomass. In the case of lipid content, S. dimorphus, C. vulgaris and consortium accumulated 36.4, 35.5 and 39.2% lipids, respectively in lab, whereas in outdoor raceway pond it was 26.4, 32.3 and 34.5%, respectively. The fatty profile of Chlorella and Scenedesmus sp. showed linolelaidic acid, and cis-8,11,14-eicosatrienoic acid as prevalent fatty acids whereas the consortium has 53.5% oleic acid than other fatty acids.

Unveiling the induced lipid production in Chlorella vulgaris under pulsed magnetic field treatment.

The pulsed magnetic field (PMF) was adopted for the enhancement of lipid in Chlorella vulgaris. The average biomass and lipid content in outdoor conditions were found to be 0.315 g.L-1 and 20-25% respectively. The effect of magnetic flux density in the range of 600-900 mG on biomass production and lipid content was studied. A magnetic flux density of 700 mG at 1Hz for 4 h per day was found to be optimum, which yielded a maximum dry cell weight of 0.61 g.L-1, two-fold than the normal condition, with a lipid content of 55.2%. FTIR analysis evidenced that the PMF treatment increased the active oxygen, which could be attributed to the enhancement of growth and lipid of C. vulgaris.

Biodegradation and Characterization of Streptomyces sp. (JMCACA3) from Acid Corroded Iron Plate.

From acid corroded iron plates five different types of actinobacteria were isolated. Among the five, JMCACA3 strain was selected for the present study. In ISP media, JMCACA3 strain showed well-developed aerial and substrate mycelia were observed. This strain showed good growth in 12 different carbon and 4 different nitrogen sources. The 16S rRNA sequence of phylogenetic analysis by neighbor-joining method identified the studied strain belongs to Streptomyces sp. The biodegradation activity of the strain analyzed by UV and FTIR analysis, which revealed that the various concentrations of Benzimidazole inhibitor with JMCACA3 culture showed slightly varied results. For weight loss method, mild steel coupons incubated with JMCACA3 culture, Benzimidazole inhibitor + JMCACA3 culture and mixed sample showed that JMCACA3 strain utilized the inhibitor as their energy source and the weight the coupons were slightly varied, evidenced by XRD spectra and showed Fe2O3 corrosion products. Our study concluded that the JMCACA3 strain, an iron-reducing actinobacteria which utilizes and converted the corrosion inhibitor Benzimidazole as their energy source. So, it is very urgent to develop more powerful corrosion inhibitor from green biocide or microbial-based biocide and their analog which incorporated into the pre-existing Benzimidazole to increase the corrosion inhibitor level against the biofilm of actinobacterial influenced corrosion.

Bioremediation of noxious metals from e-waste printed circuit boards by Frankia.

The environmental noxious e-waste was collected and physicochemical characterized by Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDX), Atomic absorption spectrometry (AAS), and X-ray diffraction analysis (XRD) exploration to understand the presence of toxic metals like Hg, Cd, Pd, Si, Ru. Therefore, the finding provides vital knowledge about the impact of toxic metals from e-waste printed circuit boards as contaminants in the environment and its impact on humans. The Frankia sp. DDNSF-03 and Frankia casuarinae DDNSF-04 were isolated and identified, further utilized for removal of e-waste toxic metals by one and two steps bioremediation experiments executed with various e-waste concentrations. The two-step bioremediation experiment is efficient in the expression of toxic metals that were removed at a lesser concentration of e-waste. Consequently, the presence of organic acids in the Frankia primary metabolites was confirmed by FT-IR analysis besides decreasing the pH level in the Frankia growth medium. The positive control Frankia and negative control e-waste were maintained throughout the bioremediation experiments. The initial Hg 4.3, Cd 8.3, Pd 4.6 (ppm) in the e-waste and final treated with Frankia sp. DDNSF-03 Hg 0.09, Cd 5.09, Pb 0.49 (ppm), and Frankia casuarinae DDNSF-04 Hg 2.15, Cd 5.6, Pb 2.82 (ppm) concentration of toxic metals was quantified by AAS spectrum analysis. The toxic metals mercury and lead were significantly mineralized by Frankia sp. when compare the Frankia casuarinae. The above finding was confirmed the manifestation of morphological changes by an accumulation of e-waste in Frankia hyphae using SEM analysis and obtain the qualitative of toxic metals parallel peaks in EDX analysis.

Enhancing starch accumulation/production in Chlorococcum humicola through sulphur limitation and 2,4- D treatment for butanol production.

Depleting fuel resources is a global concern worldwide due to the unstable and cost of fuel resources. Increased transportation has gradually depleted the fossil-based fuel resources leading to find a cost-effective, readily available, and renewable source. Considering these issues, various private and government organizations have focussed on producing bio-based fuels from natural sources. In this scenario, algae are a potential emerging source of feedstock or biomass for biobutanol production, which can effectively replace fossil fuels and their environmental drawbacks. The present study focussed on evaluating the potential of freshwater microalga Chlorococcum humicola isolated from temple pond as feedstock for biobutanol production using Clostridium acetobutylicum. The results indicated that C. humicola produced 846.33 µgmg-1of starch under full strength Chu10 medium. While under sulphur and phosphorus limitation, the accumulation of starch was 947.33 µg mg-1 and 766.67 µgmg-1, respectively. Also, C. humicola was exposed to different concentrations of 2,4-Dichlorophenoxyacetic acid (2,4-D). At 10µgml-1 of 2,4-D, the highest starch concentration of 989µgmg-1was achieved in C. humicola. Finally, starch in C. humicola were hydrolysed and ABE fermentation was performed using C. acetobutylicum under anaerobic condition in a 5 L automated fermenter. After 72 h of fermentation, the fermented broth is analyed in Gas Chromatography showing the fermented product containing Acetone: Butanol: Ethanol. The present study is the first report on the production of biobutanol from C. humicola isolated from Temple pond. This study emphasizes the importance of local isolates of microalgae as a third-generation substrate to produce butanol to replace fossil-based fuels.

Taxonomic identification and bioactive compounds characterization of Psilocybe cubensis DPT1 to probe its antibacterial and mosquito larvicidal competency.

Mushrooms have an important role in sustainability since they have long been used as valuable food source and traditional medicine around the world. Regrettably, they are among the most rigorously affected populations, along with several plants and animals, due to the destructive activities of mankind. Thus the authentication and conservation of mushroom species are constantly needed to exploit the remarkable potential in them. In this perspective, an attempt has been made to identify and assess the biological attributes of psychedelic mushrooms collected from Kodaikanal, Tamil Nadu, India. The macromorphological features of the psychedelic mushroom DPT1 helped its presumptive identification and the molecular characters depicted by DNA marker revealed its close relationship with the genus Psilocybe. Accordingly, the psychedelic mushroom was identified as Psilocybe cubensis DPT1 and its crude ethyl acetate extract on analysis revealed the occurrence of phytoconstituents like alkaloids, flavonoids, tannins, saponins and carbohydrates. Moreover, it exhibited 80% larvicidal activity against Culex quinquefasciatus mosquito at 800 ppm concentration and an array of antibacterial effects with utmost susceptibility of Proteus vulgaris, and the identification of bioactive compounds by different analytical techniques substantiate that the bioactivities might be due to the presence of phytochemicals. The results of the study indicated that the extract of P. cubensis DPT1 having notable antibacterial and mosquito larvicidal efficacies which could be probed further for the isolation of medicinally important as well as bio-control compounds.

Core/shell nanoparticles: Synthesis, investigation of antimicrobial potential and photocatalytic degradation of Rhodamine B.

Bacterial pathogenicity is becoming a major cause of morbidity and mortality around the globe. Researchers are tirelessly finding solutions to cure or prevent infections caused by bacterial pathogens. Nanotechnology is a fast-growing area of research, effectively influencing and preventing bacterial growth. Nanoparticles (NPs) of silver, copper and gold are being used to kill bacterial pathogens in the past years but the toxicity of NPs at higher concentrations remains a major problem. Therefore, in the present study, Co3O4@ZrO2 (CoZ) core/shell NPs were synthesized using a simple sol-gel method. The synthesized NPs were characterized using different analytical techniques revealing the absorption bands at 456 and 277 nm with crystalline size of ~600 nm core/shell. The functional groups and oxidation states were characterized using FTIR analysis. Further bactericidal properties of core/shell of Co3O4@ZrO2 NPs were tested against Gram negative (Escherichia coli, Pseudomonas aeruginosa) and Gram positive (Staphylococcus aureus, Bacillus subitilis) pathogens. The core/shell CoZ NPs showed maximum growth inhibitions against S. aureus and P. aeruginosa. At the highest concentration of 200 µg/mL, the maximum zone of inhibition was observed. The synthesized CoZ NPs was also subjected to photocatalytic degradation of rhodamine B in 180 min under visible light irradiation. The present study could be an innovative and efficient research for both biomedical and wastewater treatment applications.

Biocontrol and plant growth-promoting ability of plant-associated bacteria from tomato (Lycopersicum esculentum) under field condition.

Forty-five bacterial isolates recovered from surface-sterilized root, stem and leaf tissues of tomato were studied for their antifungal activity against phytopathogens, and plant growth-promoting (PGP) and biocontrol traits. Six plant-associated bacteria suppressed all the pathogens tested under in vitro plate assay and also shown PGP and biocontrol traits. The six isolates showing PGP and biocontrol properties were identified as Bacillus spp., based on the microbial identification system (Biolog) and partial sequence analysis of 16S rDNA. Two independent field trials were conducted with biocontrol bacteria along with chemical control (Thiram+Fytolan) and control (Without treatment). The averaged results of two field trails revealed that tomato plants inoculated with BETS11 (11.73 t/ha) and BETR11 (11.24 t/ha) strains showed significantly higher yield and disease reduction on par with chemical control (11.81 t/ha). However, there was an increase in the yield with respect to uninoculated control except the isolate BETS5 (9.09 t/ha). Therefore, the isolates BETS11 and BETR11 may be used as efficient biofertilizer and bio-control agent for tomato production in the Island agricultural ecosystem.

Bioconversion of curcumin into calebin-A by the endophytic fungus Ovatospora brasiliensis EPE-10 MTCC 25236 associated with Curcuma caesia.

Calebin-A is a curcuminoid compound reported to be present in Curcuma longa rhizome. The current study was aimed to isolate and characterize calebin-A from Curcuma caesia rhizome and its production through biotransformation approach using endophytic fungus. C. caesia rhizomes of different ages were subjected to analysis in order to investigate the age at which maximum calebin-A content is present. HP-TLC profiles, HPLC retention times and mass spectrometry detector confirmed the occurrence of calebin-A in C. caesia rhizomes of 12 to 14 months of age but not in rhizomes younger to 12 months. Furthermore, an endophytic fungus strain, EPE-10 that was isolated from the medicinal plant C. caesia was identified as Ovatospora brasiliensis based on morphological and molecular characteristics. This strain O. brasiliensis was deposited to the culture collected centre, MTCC Chandigarh, India under the Budapest treaty and was designated with the Accession Number MTCC 25236. Biotransformation process was carried out at 37 ± 0.5 °C with shaking for 7 days after addition of 0.01% w/v curcumin. Extraction of biotransformed products was done by following partition method and the extracts obtained were analyzed using HPTLC, HPLC and LCMS. The data of the study suggested that O. brasiliensis MTCC 25236 was found to convert curcumin to calebin-A in a time dependant manner with optimum conversion at 48 h. Furthermore, O. brasiliensis MTCC 25236 was found to be positive for the Baeyer-Villiger monooxygenase (BVMOs) enzyme activity which could possibly be the mechanism of this bioconversion. The results of this study for the first time indicated that the endophytic fungus identified as O. brasiliensis MTCC 25236 isolated from the C. caesia rhizome could be a possible source for naturally producing calebin-A.

Impact of l-Arginine and l-Histidine on the structural, optical and antibacterial properties of Mg doped ZnO nanoparticles tested against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli.

Magnesium doped Zinc oxide nanoparticles (Mg:ZnO NPs) were synthesized by co-precipitation method. The synthesized Mg:ZnO NPs exhibited hexagonal wurtzite structure, which was confirmed by X-ray diffraction results. After structural confirmation of Mg doped ZnO NPs, base amino acids like l-Arginine and l-Histidine were separately incorporated with the Mg: ZnO NPs. l-Arginine added Mg:ZnO (Mg:ZnO:LA) and l-Histidine added Mg:ZnO (Mg:ZnO: LH) NPs retained the same wurtzite hexagonal structure and average crystallite sizes of Mg: ZnO:LA and Mg: ZnO:LH NPs were found to be 25 nm and 20 nm respectively. The sizes of Mg:ZnO:LH and Mg: ZnO: LA NPs decreased as compared to that of the Mg doped ZnO NPs. From the FT-IR spectra, the ZnO stretching frequencies were observed at 516, 517 and 518 cm-1 for Mg:ZnO, Mg:ZnO: LA and Mg: ZnO:LH NPs respectively. From the FESEM images, the morphologies of ZnO:Mg and ZnO:Mg:LA NPs were spherical and the Mg: ZnO: LH NPs formed nano-flakes structure. From the EDAX study, the amount of elements incorporated in the samples was determined. The photoluminescence measurements revealed the existence of zinc vacancies, oxygen vacancies and surface defects of the samples. Antibacterial activity of the amino acid added Mg doped ZnO NPs was studied against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli (E. coli).The Minimal Inhibitory Concentration (MIC) of the LH added ZnO:Mg NPs was found to be 1000 µg/ml for which the growth of E. coli completely inhibited. l-Histidine added Mg doped ZnO NPs showed the highest antibacterial activity as compared to that of the Mg:ZnO NPs and ZnO:Mg:LA NPs.

In vitro and in silico attenuation of quorum sensing mediated pathogenicity in Pseudomonas aeruginosa using Spirulina platensis.

Biofilm forming pathogenic bacteria showing resistance towards antimicrobial agents has increased the urge to find an alternative treatment strategy. Among the biofilm forming pathogenic bacteria, Pseudomonas aeruginosa is a well-recognised Gram negative biofilm former causing nosocomial infection and other disease among immunocompromised patients. The aim of the current study is to evaluate the antipathogenic potentials of S. platensis against P. aeruginosa. S. platensis methanolic extract (SME) inhibited the biofilm (89%), extracellular polymeric substances (EPS), cell surface hydrophobicity (CSH) (44%), pyocyanin, pyoveridin and swarming motility of P. aeruginosa. Partial purification of SME using thin layer chromatography (TLC), column chromatography and gas chromatography mass spectroscopy (GCMS) revealed the major component as hexadecanoic acid (HxD). Further analysis through in silico approach showed the efficient binding of HxD with the biofilm regulatory proteins (Las R and salidase enzyme) of P. aeruginosa. The coating of HxD over different material surfaces efficiently prevented the adhesion of P. aeruginosa biofilm. The results of the toxicity assay revealed that the SME is non-toxic towards Artemia salina at the given concentration. Hence the overall work proves the potential non-toxic effects of SME against P. aeruginosa pathogenicity.

Microfouling inhibition of human nosocomial pathogen Pseudomonas aeruginosa using marine cyanobacteria.

Pseudomonas aeruginosa is a Gram negative, opportunistic biofilm forming pathogenic bacterium which is developing as a serious problem worldwide. The pathogenicity of P. aeruginosa mainly depends upon biofilm and quorum sensing (QS) mechanism. Targeting biofilm and QS regulated factor will automatically reduce the pathogenicity of P. aeruginosa. Therefore it is compulsory to identify naturally derived biofilm and QS inhibitors against P. aeruginosa. In the present study Oscillatoria subuliformis, a marine cyanobacterium was used against the biofilm and QS of P. aeruginosa. O. subuliformis intracellular methanolic extract (OME) at different concentration (1.5 µg mL-1, 3 µg mL-1 and 5 µg mL-1) was tested against several virulence factors like Extracellular Polymeric Substance (EPS), Cell Surface Hydrophobicity (CSH), elastase, pyocyanin and swarming motility. OME inhibited biofilm (56%), EPS (40%), CSH (56%), pyocyanin (27%), elastase activity and swarming motility in P. aeruginosa without interfering in their survival. Characterization of the OME using FTIR and GCMS confirmed palmitic acid and oleic acid as active compound. CLSM analysis of catheter coated with OME, palmitic and oleic acid proved biofilm inhibition over urinary catheters. The results postulates that oleic and palmitic acid could be an effective attenuator of P. aeruginosa pathogenesis.

An enhancement of antimicrobial efficacy of biogenic and ceftriaxone-conjugated silver nanoparticles: green approach.

Of the various methods explored for the synthesis of nanoparticles, biogenesis of silver nanoparticles (AgNPs) received great attention due to their versatile properties. In this report, Daucus carota extract was used for the synthesis of AgNPs and ceftriaxone was conjugated with AgNPs to enhance their antimicrobial efficacy. The conjugated and unconjugated AgNPs were characterized by adopting UV-Vis spectroscopy, FTIR, AFM, DLS, and TEM, which revealed the SPR peak at 420 nm and spherical shaped nanoparticles of 20 nm size, respectively. The antimicrobial efficacies of the unconjugated AgNPs and ceftriaxone-conjugated AgNPs were tested against ceftriaxone-resistant human pathogens, Bacillus cereus, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The ceftriaxone-conjugated AgNPs showed high inhibitory action (23 mm) than the unconjugated AgNPs (18 mm) at the concentration of 50 µg/mL. Both the unconjugated and ceftriaxone-conjugated AgNPs were found to be non-toxic on EAC cells at 50 µg/mL. The dose-dependent cytotoxic activities were observed on increasing the concentration of the AgNPs. The ceftriaxone-conjugated AgNPs showed high activity than the unconjugated AgNPs. The enhanced activity could be useful to treat ceftriaxone-resistant human pathogens.

Synthesis of nano-cuboidal gold particles for effective antimicrobial property against clinical human pathogens.

Algae could offer a potential source of fine chemicals, pharmaceuticals and biofuels. In this study, a green synthesis of dispersed cuboidal gold nanoparticles (AuNPs) was achieved using red algae, Gelidium amansii reacted with HAuCl4. It was found to be 4-7 nm sized cubical nanoparticles with aspect ratio of 1.4 were synthesized using 0.5 mM of HAuCl4 by HRSEM analysis. The crystalline planes (111), (200), (220), (311) and elemental signal of gold was observed by XRD and EDS respectively. The major constitutes, galactose and 3,6-anhydrogalactose in the alga played a critical role in the synthesis of crystalline AuNPs with cubical dimension. Further, the antibacterial potential of synthesized AuNPs was tested against human pathogens, Escherichia coli and Staphylococcus aureus. The synthesized AuNPs found biocompatible up to 100 ppm and high concentration showed an inhibition against cancer cell. This novel report could be helped to exploration of bioresources to material synthesis for the application of biosensor and biomedical application.

Unraveling the presence of multi-class toxins from Trichodesmium bloom in the Gulf of Mannar region of the Bay of Bengal.

Trichodesmium is an enigmatic bloom forming, non-heterocystous cyanobacterium reported most frequently in the coastal waters of India. However, the toxigenic potential of this globally significant N2 fixing cyanobacterium has not been characterized. In this study, we report for the first time the presence of potent multi-class neurotoxins such as Anatoxin-a, Saxitoxins, Gonyautoxin and hepatotoxins like MC-LR, MC-YA from a bloom material of Trichodesmium sp. MBDU 524 collected at the Gulf of Mannar region. Toxins were determined using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis of HPLC purified aqueous and solvent fractions. Molecular phylogenetic analysis through 16S rRNA gene sequencing showed the close relationship with Trichodesmium erythraeum clade. The toxigenic potential was validated through brine shrimp toxicity assay and showed 100% mortality after 48 h of incubation. The results suggest the potential toxigenic and environmental impacts of Trichodesmium bloom sample from the Gulf of Mannar region.

Inhibitory Effect of Biosynthesized Silver Nanoparticles from Extract of Nitzschia palea Against Curli-Mediated Biofilm of Escherichia coli.

Extended spectrum beta lactamase (ESBL) are emerging beta-lactamases in Gram-negative pathogens, causing serious problems in hospitalized patients worldwide. Biofilm mode of virulence has decreased the efficiency of antibiotics used for treatment against ESBL pathogens. Therefore, there is an urgent need for alternative agents such as nanoparticles that can prevent and inhibit the biofilm formation. The aim of the present study was to inhibit the biofilm formed by ESBL-producing Escherichia coli using silver nanoparticles (AgNPs) synthesized with fresh water diatom (Nitzschia palea). AgNPs were characterized using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), and XRD. AgNPs at their biofilm inhibitory concentration (BIC) of 300 ng ml-1 significantly reduced the biofilm formed by E. coli. Interestingly, Congo red assay revealed the reduction of curli, essential for biofilm formation in the presence of AgNPs. Light and CLSM examination of the biofilm images also validated that in the presence of AgNPs, the biofilm architecture was disintegrated and the thickness was significantly reduced. Overall, the present study exemplifies the use of AgNPs as a plausible alternative for conventional coating agents on implant devices to prevent and control biofilm-associated urinary tract infections.