Impact of anthropogenic accumulation on phytoplankton community and harmful algal bloom in temporarily open/closed estuary.

Spatio-temporal variation in phytoplankton community dynamics in a temporarily open/closed Swarnamukhi river estuary (SRE), located on the South East coast of India was investigated and correlated to that of the adjacent coastal waters. Understanding the seasonal variability of the phytoplankton community and influencing factors are essential to predicting their impact on fisheries as the river and coastal region serve as the main source of income for the local fishing communities. Downstream before the river meets the sea, an arm of the Buckingham Canal (BC), carrying anthropogenic inputs empties into the Swarnamukhi River (SR1). The impact of anthropogenic effects on the phytoplankton community at BC was compared to other estuarine stations SR2 (upstream), SR1 (downstream), SRM (river mouth) and coastal station (CS). In BC station, harmful algal blooms (HABs) of Chaetoceros decipiens (2940 × 103 cells L-1) and Oscillatoria sp. (1619 × 103 cells L-1) were found during the southwest monsoon and winter monsoon, respectively. These HABs can be linked to the anthropogenic input of increased nutrients and trace metals. The HABs of Oscillatoria sp. were shown to be induced by elevated concentrations of nitrate (10.18 µM) and Ni (3.0 ppm) compared to ambient, while the HABs of C. decipiens were caused by elevated concentrations of silicate (50.35 µM), nitrite (2.1 µM), and phosphate (4.37 µM). Elevated nutrients and metal concentration from the aquaculture farms, and other anthropogenic inputs could be one of the prime reasons for the recorded bloom events at BC station. During this period, observed bloom species density was found low at other estuarine stations and absent at CS. The formation of bloom events during the closure of the river mouth could be a major threat to the coastal ecosystem when it opens. During the Osillatoria sp. bloom, both the Cu and Ni levels were higher at BC. The elevated concentration of nutrients and metals could potentially affect the coastal ecosystem and in turn fisheries sector in the tropical coastal ecosystem.

Bioprospecting of unexplored halophilic actinobacteria against human infectious pathogens.

Human pathogenic diseases received much attention recently due to their uncontrolled spread of antimicrobial resistance (AMR) which causes several threads every year. Effective alternate antimicrobials are urgently required to combat those disease causing infectious microbes. Halophilic actinobacteria revealed huge potentials and unexplored cultivable/non-cultivable actinobacterial species producing enormous antimicrobials have been proved in several genomics approaches. Potential gene clusters, PKS and NRPKS from Nocardia, Salinospora, Rhodococcus, and Streptomyces have wide range coding genes of secondary metabolites. Biosynthetic pathways identification via various approaches like genome mining, In silico, OSMAC (one strain many compound) analysis provides better identification of knowing the active metabolites using several databases like AMP, APD and CRAMPR, etc. Genome constellations of actinobacteria particularly the prediction of BGCs (Biosynthetic Gene Clusters) to mine the bioactive molecules such as pigments, biosurfactants and few enzymes have been reported for antimicrobial activity. Saltpan, saltlake, lagoon and haloalkali environment exploring potential actinobacterial strains Micromonospora, Kocuria, Pseudonocardia, and Nocardiopsis revealed several acids and ester derivatives with antimicrobial potential. Marine sediments and marine macro organisms have been found as significant population holders of potential actinobacterial strains. Deadly infectious diseases (IDs) including tuberculosis, ventilator-associated pneumonia and Candidiasis, have been targeted by halo-actinobacterial metabolites with promising results. Methicillin resistant Staphylococus aureus and virus like Encephalitic alphaviruses were potentially targeted by halophilic actinobacterial metabolites by the compound Homoseongomycin from sponge associated antinobacterium. In this review, we discuss the potential antimicrobial properties of various biomolecules extracted from the unexplored halophilic actinobacterial strains specifically against human infectious pathogens along with prospective genomic constellations.

Gracilaria salicornia as potential substratum for green synthesis of Cerium Oxide Nanoparticles coupled hydrogel: An effective antimicrobial thin film.

Sodium alginate based (SA) hydrogel supplemented Cerium Oxide nanoparticles (CeO2NPs) was produced to fabricate an antimicrobial thin film using an aqueous extract of G. salicornia (Gs). The Gs-CeO2NPs were characterized via SEM, FT-IR, EDX, XRD and DLS, the particle size was 200 nm, agreed with XRD. Gs-SA powder was extracted and incorporated with CeO2NPs. The Gs-SA and its composite thin film (Gs-CeO2NPs-SATF) were characterized including viscosity, FT-IR, TGA, and SEM. The adhesion of Gs-SA coating around Gs-CeO2NPs confirmed via FTIR. The antimicrobial properties of Gs-CeO2NPs and CeO2NPs-SATF were proved in MICs for E. coli and Candida albicans at 62.5 and 250.0 µg/mL. The biofilm inhibition efficiency of CeO2NPs-SATF was 74.67 ± 0.98% and 65.45 ± 0.40% for E. coli and Candida albicans. The CeO2NPs-SATF was polydisperse in nature and film structure gets fluctuated with NPs concentration. Increased NPs into SATF enhances pore size of gel and corroborated with viscous behaviour. The cytotoxicity of Gs-CeO2NP-SA in Artemia salina at higher concentration 100 µg/mL provides less lethal effect into the adult. The antioxidant activity of Gs-CeO2NP-SA in DPPH assay was noticed at 0.6 mg ml-1 with radical scavenging activity at 65.85 ± 0.81%. Thus the Gs-CeO2NP-SATF would be suitable in antimicrobial applications.

Hydrothermal synthesis of spindle structure copper ferrite-graphene oxide nanocomposites for enhanced photocatalytic dye degradation and in-vitro antibacterial activity.

In this study, a one-step hydrothermal approach was used to make pure magnetic copper ferrite (CuFe2O4) and copper ferrite-graphene oxide (CuFe2O4-rGO) nanocomposites (NCs) and spinel structure CuFe2O4 with a single phase of tetragonal CuFe2O4-rGO-NCs was confirmed by the XRD. Then, characterization of CuFe2O4-rGO-NCs was done using ng Raman spectroscopy, FT-IR, TGA-DTA, EDS, SEM, and TEM. The synthesized NCs was exposed to UV light to evaluate its photocatalytic activity for the degradation of methylene blue (MB) and rhodamine B (RhB) with CuFe2O4 and CuFe2O4-rGO-NCs, respectively. The catalyst CuFe2O4-rGO-NCs provided higher degradation of MB (94%) than for RhB (86%) under UV light irradiation compared to CuFe2O4. Further, the antibacterial activities of CuFe2O4-NPs and CuFe2O4-rGO-NCs were tested against Gram-negative and -positive bacterial pathogens such as Vibrio cholera (V. cholera); Escherichia coli (E. coli); Pseudomonas aeruginosa (P. aeruginosa); Bacillus subtilis (B. subtilis); Staphylococcus aureus (S. aureus); and Staphylococcus epidermidis (S. epidermidis) by well diffusion method. At 100 µg/mL concentrations of CuFe2O4-rGO-NCs, maximal growth inhibition was shown against E. coli (18 mm) and minimum growth inhibition against S. epidermidis (12 mm). This study suggests that CuFe2O4-rGO-NCs as a high-efficacy antibacterial material and plays an important role in exhibiting higher sensitivity depending on concentrations. The results encourage that the synthesized CuFe2O4-rGO-NCs can be used as a promising material for the antibacterial activity and also for dye degradation in the water/wastewater treatment plants.

Synthesis of Bimetallic BiPO4/ZnO Nanocomposite: Enhanced Photocatalytic Dye Degradation and Antibacterial Applications.

Multidrug-resistant strains (MDRs) are becoming a major concern in a variety of settings, including water treatment and the medical industry. Well-dispersed catalysts such as BiPO4, ZnO nanoparticles (NPs), and different ratios of BiPO4/ZnO nanocomposites (NCs) were synthesized through hydrothermal treatments. The morphological behavior of the prepared catalysts was characterized using XRD, Raman spectra, PL, UV-Vis diffuse reflectance spectroscopy (UV-DRS), SEM, EDX, and Fe-SEM. MDRs were isolated and identified by the 16s rDNA technique as belonging to B. flexus, B. filamentosus, P. stutzeri, and A. baumannii. The antibacterial activity against MDRs and the photocatalytic methylene blue (MB) dye degradation activity of the synthesized NPs and NCs were studied. The results demonstrate that the prepared BiPO4/ZnO-NCs (B1Z4-75:300; NCs-4) caused a maximum growth inhibition of 20 mm against A. baumannii and a minimum growth inhibition of 12 mm against B. filamentosus at 80 µg mL-1 concentrations of the NPs and NCs. Thus, NCs-4 might be a suitable alternative to further explore and develop as an antibacterial agent. The obtained results statistically justified the data (p ≤ 0.05) via one-way analysis of variance (ANOVA). According to the results of the antibacterial and photocatalytic study, we selected the best bimetallic NCs-4 for the photoexcited antibacterial effect of MDRs, including Gram ve+ and Gram ve- strains, via UV light irradiation. The flower-like NCs-4 composites showed more effectiveness than those of BiPO4, ZnO, and other ratios of NCs. The results encourage the development of flower-like NCs-4 to enhance the photocatalytic antibacterial technique for water purification.

Evaluating different web applications to assess the toxicity of plasticizers.

Plasticizers increase the flexibility of plastics. As environmental leachates they lead to increased water and soil pollution, as well as to serious harm to human health. This study was set out to explore various web applications to predict the toxicological properties of plasticizers. Web-based tools (e.g., BOILED-Egg, LAZAR, PROTOX-II, CarcinoPred-EL) and VEGA were accessed via an 5th-10th generation computer in order to obtain toxicological predictions. Based on the LAZAR mutagenicity assessment was only bisphenol F predicted as mutagenic. The BBP and DBP in RF; DEHP in RF and XGBoost; DNOP in RF and XGBoost models were predicted as carcinogenic in the CarcinoPred-EL web application. From the bee predictive model (KNN/IRFMN) BPF, di-n-propyl phthalate, diallyl phthalate, dibutyl phthalate, and diisohexyl phthalate were predicted as strong bee toxicants. Acute toxicity for fish using the model Sarpy/IRFMN predicted 19 plasticizers as strong toxicants with LC50 values of less than 1 mg/L. This study also considered plasticizer effects on gastrointestinal absorption and other toxicological endpoints.

Bioactive Efficacy of Novel Carboxylic Acid from Halophilic Pseudomonas aeruginosa against Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) infections are increasingly causing morbidity and mortality; thus, drugs with multifunctional efficacy against MRSA are needed. We extracted a novel compound from the halophilic Pseudomonas aeruginosa using an ethyl acetate (HPAEtOAcE). followed by purification and structure elucidation through HPLC, LCMS, and 1H and 13C NMR, revealing the novel 5-(1H-indol-3-yl)-4-pentyl-1,3-oxazole-2-carboxylic acid (Compound 1). Molecular docking of the compound against the MRSA PS (pantothenate synthetase) protein was confirmed using the CDOCKER algorithm in BDS software with specific binding to the amino acids Arg (B:188) and Lys (B:150) through covalent hydrogen bonding. Molecular dynamic simulation of RMSD revealed that the compound-protein complex was stabilized. The proficient bioactivities against MRSA were attained by the HPAEtOAcE, including MIC and MBCs, which were 0.64 and 1.24 µg/mL, respectively; 100% biomass inhibition and 99.84% biofilm inhibition were observed with decayed effects by CLSM and SEM at 48 h. The hla, IrgA, and SpA MRSA genes were downregulated in RT-PCR. Non-hemolytic and antioxidant potential in the DPPH assay were observed at 10 mg/mL and IC50 29.75 ± 0.38 by the HPAEtOAcE. In vitro growth inhibition assays on MRSA were strongly supported by in silico molecular docking; Lipinski's rule on drug-likeness and ADMET toxicity prediction indicated the nontoxic nature of compound.

Recent Antimicrobial Responses of Halophilic Microbes in Clinical Pathogens.

Microbial pathogens that cause severe infections and are resistant to drugs are simultaneously becoming more active. This urgently calls for novel effective antibiotics. Organisms from extreme environments are known to synthesize novel bioprospecting molecules for biomedical applications due to their peculiar characteristics of growth and physiological conditions. Antimicrobial developments from hypersaline environments, such as lagoons, estuaries, and salterns, accommodate several halophilic microbes. Salinity is a distinctive environmental factor that continuously promotes the metabolic adaptation and flexibility of halophilic microbes for their survival at minimum nutritional requirements. A genetic adaptation to extreme solar radiation, ionic strength, and desiccation makes them promising candidates for drug discovery. More microbiota identified via sequencing and 'omics' approaches signify the hypersaline environments where compounds are produced. Microbial genera such as Bacillus, Actinobacteria, Halorubrum and Aspergillus are producing a substantial number of antimicrobial compounds. Several strategies were applied for producing novel antimicrobials from halophiles including a consortia approach. Promising results indicate that halophilic microbes can be utilised as prolific sources of bioactive metabolites with pharmaceutical potentialto expand natural product research towards diverse phylogenetic microbial groups which inhabit salterns. The present study reviews interesting antimicrobial compounds retrieved from microbial sources of various saltern environments, with a discussion of their potency in providing novel drugs against clinically drug-resistant microbes.

Shallow Hydrothermal Vent Bacteria and Their Secondary Metabolites with a Particular Focus on Bacillus.

Extreme environments are hostile for most organisms, but such habitats represent suitable settings to be inhabited by specialized microorganisms. A marine shallow-water hydrothermal vent field is located offshore in northeast Taiwan, near the shallow shore of the southeast of Kueishantao Island (121°55' E, 24°50' N). Research on extremophilic microorganisms makes use of the biotechnological potential associated with such microorganisms and their cellular products. With the notion that extremophiles are capable of surviving in extreme environments, it is assumed that their metabolites are adapted to function optimally under such conditions. As extremophiles, they need specific culture conditions, and only a fraction of species from the original samples are recovered in culture. We used different non-selective and selective media to isolate bacterial species associated with the hydrothermal vent crab Xenograpsus testudinatus and the sediments of its habitat. The highest number of colonies was obtained from Zobell marine agar plates with an overall number of 29 genetically distinct isolates. 16sRNA gene sequencing using the Sanger sequencing method revealed that most of the bacterial species belonged to the phylum Firmicutes and the class Bacilli. The present study indicates that hydrothermal vent bacteria and their secondary metabolites may play an important role for the reconstruction of the evolutionary history of the phylum Procaryota.

Marine Bacterial Compounds Evaluated by In Silico Studies as Antipsychotic Drugs Against Schizophrenia.

Schizophrenia (SCZ) is one of the brain disorders which affects the thinking and behavioral skills of patients. This disorder comes along with an overproduction of kynurenic acid in the cerebrospinal fluid and the prefrontal cortex of SCZ patients. In this study, marine bacterial compounds were screened for their suitability as antagonists against human kynurenine aminotransferase (hKAT-1) which causes the synthesis of kynurenic acid downstream which ultimately causes the SCZ disorder according to the kynurenic hypothesis of SCZ. The marine actinobacterial compound bonactin shows more promising results than other tested marine compounds such as the histamine H2 blocker famotidine and indole-3-acetic acid (IAC) from docking and in silico toxicological studies carried out here. The obtained results of the Grid-based Ligand Docking with Energetics (Glide) scores of extra-precision (XP) Glide against the target protein hKAT-1 on IAC, famotidine, and bonactin were - 6.581, - 6.500 and - 7.730 kcal/mol where Glide energies were - 29.84, - 28.391, and - 47.565 kcal/mol, respectively. Bonactin is known as an antibacterial and antifungal compound being extracted from a marine Streptomyces sp. Comparing tested compounds against the drug target hKAT-1, bonactin alone showed the best Glide score and Glide energy on the target protein hKAT-1.

Biogenic corrosion inhibitor on mild steel protection in concentrated HCl medium.

Turbinaria ornata (TO) extract was tested as green corrosion inhibitor on mild steel (MS) coupons in conc. HCl medium with an efficiency of 100% at 25 g l-1 during 5 min exposure. Antibacterial efficacy performed against 16 S rDNA identified marine biofilming bacteria (MBB) and human pathogenic bacteria (HPB). Maximum inhibition growth was 16 mm on MBB observed in Bacillus megaterium (MBF14 - AB894827) and 20 mm on HPB in Escherichia coli (B5 - NCIM 2931). Similarly, minimum of 10 mm on MBB witnessed in Pseudomonas sp., (MBF9 - AB894829). Toxicity studies proved 50.0% LC50 at 500 µg ml-1 in 24 hrs, whereas Balanus amphitrite resulted in 100% mortality within 12 hrs. Results including weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy, FT-IR and GC-MS confirm 10-Octadecaonic acid as a major corrosion inhibitor from T. ornata and is discovered as a novel antifoulant. Anticorrosion formulation will become available soon.

Antifouling assessments on biogenic nanoparticles: A field study from polluted offshore platform.

Turbinaria ornata mediated silver nanoparticles (TOAg-NPs) were evaluated for antibacterial activity against 15 biofilm forming bacterial isolates. A field study in natural seawater for 60 days showed antifouling activity of TOAg-NPs on stainless steel coupons (SS-304) coated with Apcomin zinc chrome (AZC) primer. Though TOAg-NPs showed broad spectrum of antibacterial activity, the maximum zone of inhibition was with Escherichiacoli (71.9%) and a minimum with Micrococcus sp. (40%) due to the EPS secretion from Gram-positive bacteria. Compared to control coupons (18.9 [ × 10(3)], 67.0 [× 10(3)], 13.5 [ × 10(4)] and 24.7 [ × 10(4)]CFU/cm(2)), experimental biocide coupons (71.0 [ × 10(2)], 32.0 [ × 10(3)], 82.0 [ × 10(3)] and 11.3 [ × 10(4)]CFU/cm(2)) displayed lesser bacterial population density. Toxicity studies revealed 100% mortality for Balanus amphitrite larvae at 250 µg ml(-1) concentration within 24h, while 56.6% recorded for Artemia marina at the same concentration indicating less toxicity to non target species. It proved that AZC+TOAg-NPs prevent biofouling by its Ag-NS affinity and antimicrobial effectivity.