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Staphylococcus aureus is not only part of normal flora but also an opportunistic pathogen relevant to microbial genomics, public health, and veterinary medicine. In addition to being a wel...

Quinalphos (QP), an organophosphate pesticide is used worldwide in agricultural practices. Extensive use of pesticides creates toxicological and environmental nuisances on non-target organisms, where it severely affects cholinergic neurons in higher animals and also induces Parkinson, Alzheimer's disease and male sterility in humans. This study evaluated the sublethal effects of QP using Caenorhabditis elegans on the endpoints of body bend frequency, head thrash frequency, feeding activity for the assay as toxicity parameters. To assess the molecular-level effect, expression pattern of genes associated with locomotion (unc-47, unc-13), pharyngeal pumping (egl-30), epigenetic modulation (utx-1), and oxidative stress (daf-2, daf-16, age-1 and glod-4) was investigated by semi-quantitative PCR. The LC50 value of QP was 0.0323 mM for 1 h of exposure, and L4-stage worms were exposed to sublethal concentrations of 0.00344 mM. After QP exposure, body bend frequency, head thrash frequency and feeding behavior of worms was significantly decreased. Expression analysis results indicate that QP exposure leads to the up-regulation in expression of some stress genes (daf-16 and glod-4) and pharyngeal pumping (egl-30), while other genes responsible for stress like daf-2 and age-1, locomotion (unc-13 and unc-47) and epigenetic modulation (utx-1) are down-regulated. Subsequently, transgenic worms expressing daf-16::GFP were exposed to QP, where induced expression of DAF-16 was evident. Overall, it appears to recruit daf-2/insulin receptor and daf-16/FOXO-dependent pathways to rescue the animals from QP-mediated oxidative stress. Alterations in the expression of many genes by QP are unveiled for the first time in this study, which could serve as biomarkers for monitoring QP exposure.

Background: Genomic Islands (GIs) are commonly believed to be relics of horizontal transfer and associated with specific metabolic capacities, including virulence of the strain. Horizontal gene transfer (HGT) plays a vital role in the acquisition of GIs and the evolution and adaptation of bacterial genomes.Objective: The present study was designed to predict the GIs and role of HGT in evolution of livestock-associated Staphylococcus aureus (LA-SA).Methods: GIs were predicted with two methods namely, Ensemble algorithm for Genomic Island Detection (EGID) tool, and Seq word Sniffer script. Functional characterization of GI elements was performed with clustering of orthologs. The putative donor predictions of GIs was done with the aid of the pre_GI database.Results: The present study predicted a pan of 46 GIs across the LA-SA genomes. Functional characterization of GI sequences revealed few unique results like the presence of metabolic operons like leuABCD and folPK genes in GIs and showed the importance of GIs in the adaptation to the host niche. The developed framework for GI donor prediction results revealed Rickettsia and Mycoplasma as the major donors of GI elements.Conclusions: The role of GIs during the evolutionary race of LA-SA could be concluded from the present study. Niche adaptation of LA-SA enhanced presumably due to these GIs. Future studies could focus on the evolutionary relationships between Rickettsia and Mycoplasma sp. with S. aureus and also the evolution of Leucine/Isoleucine mosaic operon (leuABCD).

Upon entry into the environment, nanoparticles undergo agglomeration and biological or chemical transformation to other chemicals and results in toxic effects on marine biota. The Gulf of Mannar is the richest biological region and is found to be the habitat of seaweed resources. Recent investigations have established that significant accumulation of nanoparticles (NPs) occurs in aquatic biofilms. The most active fractions of bacteria are known as biofilms. In this study nine bacteria were screened from the surface of 10 different seaweeds and interacted with three nanoparticles (Silver, Zinc oxide, Titanium dioxide nanoparticles) at four different concentrations (0.1, 1, 10, 100 mg/L) each respectively. It has been found from the experiments that a reduction in the growth, biofilm formation and exopolysaccharides production was noted at higher concentration of nanoparticles (100 mg/L). Whereas at lower concentration (1, 10 mg/L) growth curve was similar to control but biofilm formation varied. Thus marine bacteria are tolerant to certain concentration of nanoparticles. Though engineered nanoparticles are best suited for various environmental works, it has its own limitations as it is found to be dangerous finally.

Bioactive polysaccharides extracted from brown seaweeds have potent antioxidant, antitumor, antibacterial, antiviral, anti-inflammatory activities and nanomedicine applications. In the present study, we have made an attempt to overcome the instability and bioavailability problem of exopolysaccharides extracted from brown seaweed (Sargassum longifolium) by nanoencapsulation technology to enhance its therapeutic applications. Exopolysaccharides was encapsulated in orange oil nanoemulsion (NE) prepared by ultra-sonication method and nanostructured lipid carrier (NLC) prepared by hot solvent diffusion method. The encapsulation efficiency of nanoemulsion was 67.29% and of nanostructured lipid carrier was 78.7%. The prepared nano carriers have particle size 178 nm (NE), 153 nm (NLC) and zeta potential −43.9 mV (NE), −60 mV (NLC). In vitro release kinetics of exopolysaccharides from NE (80%) and NLC (95%) was found to be slow and sustained release which indicates increase in bioavailability. The cytotoxic effect of seaweed polysaccharide, nanocarriers loaded with seaweed polysaccharide was analyzed by MTT method in colon cancer (HCT 116) cell lines with the results revealing that seaweed polysaccharide encapsulated with NLC (80%) was superior to that encapsulated with orange oil nanoemulsion (70%). This is the first report demonstrating the potential of brown seaweed exopolysaccharide encapsulated in orange oil nanoemulsion and nanostructured lipid carrier for its biomedical application.

Aim The study aimed to assess the nature of animal origin Staphylococcus aureus strains. The study has zoonotic importance and aimed to compare virulence between two different hosts, i.e., bovine and ovine origin. Materials and methods Conventional polymerase chain reaction-based methods used for the characterization of S. aureus strains and chick embryo model employed for the assessment of virulence capacity of strains. All statistical tests carried on R program, version 3.0.4. Results After initial screening and molecular characterization of the prevalence of S. aureus found to be 42.62% in bovine origin samples and 28.35% among ovine origin samples. Meanwhile, the methicillin-resistant S. aureus prevalence is found to be meager in both the hosts. Among the samples, only 6.8% isolates tested positive for methicillin resistance. The biofilm formation quantified and the variation compared among the host. A Welch two-sample t-test found to be statistically significant, t=2.3179, df=28.103, and p=0.02795. Chicken embryo model found effective to test the pathogenicity of the strains. Conclusion The study helped to conclude healthy bovines can act as S. aureus reservoirs. Bovine origin S. aureus strains are more virulent than ovine origin strains. Bovine origin strains have high probability to become zoonotic pathogen. Further, gene knock out studies may be conducted to conclude zoonocity of the bovine origin strains.

Bioactive polysaccharides extracted from brown seaweeds have potent antioxidant, antitumor, antibacterial, antiviral, anti-inflammatory activities and nanomedicine applications. In the present study, we have made an attempt to overcome the instability and bioavailability problem of exopolysaccharides extracted from brown seaweed (

Aim: The study aimed to assess the nature of animal origin Staphylococcus aureus strains. The study has zoonotic importance and aimed to compare virulence between two different hosts, i.e., bovine and ovine origin. Materials and Methods: Conventional polymerase chain reaction-based methods used for the characterization of S. aureus strains and chick embryo model employed for the assessment of virulence capacity of strains. All statistical tests carried on R program, version 3.0.4. Results: After initial screening and molecular characterization of the prevalence of S. aureus found to be 42.62% in bovine origin samples and 28.35% among ovine origin samples. Meanwhile, the methicillin-resistant S. aureus prevalence is found to be meager in both the hosts. Among the samples, only 6.8% isolates tested positive for methicillin resistance. The biofilm formation quantified and the variation compared among the host. A Welch two-sample t-test found to be statistically significant, t=2.3179, df=28.103, and p=0.02795. Chicken embryo model found effective to test the pathogenicity of the strains. Conclusion: The study helped to conclude healthy bovines can act as S. aureus reservoirs. Bovine origin S. aureus strains are more virulent than ovine origin strains. Bovine origin strains have high probability to become zoonotic pathogen. Further, gene knock out studies may be conducted to conclude zoonocity of the bovine origin strains.

Genomic Islands (GIs) are commonly believed to be relics of horizontal transfer and associated with specific metabolic capacities, including virulence of the strain. Staphylococcus aureus is a commensal, Gram-positive bacteria found in both animals and humans. Amid stress or immune compromised conditions of the host, the bacteria known to induce diseases. In this study, we predicted GIs, a relative dissection and portrayed significant virulence factors associated with GIs. The study recognized distinct regions of the GIs of S. aureus RF122 which imparted with the other strains. Many GIs of RF122 strain homologous to other strains and sharing common lineage. In spite of its small genome size RF122 strain harbours 18 GIs evident for rapid horizontal gene transfer events during its evolution. It has cconcluded from the mechanisms involved in gene transfer, phage infections and transposase are important mechanisms of the horizontal transfer in the study strains. Resistance Islands and Pathogenicity islands are common subtypes of predicted GIs of study genomes. Drug resistance and virulence of S. aureus enhanced because of GIs. Another important finding of this study is it also proved S. aureus adopted to host niche because of horizontally acquired GIs. Based on sequence similarity it suggests that ST398 strain has evolved recently. Further, GI Knockout studies needed for validation of role of GIs in transforming commensal to virulent strain.