Among the trace elements, selenium (Se) has great demand as a health supplement. Compared to its other forms, selenium nanoparticles have minor toxicity, superior reactivity, and excellent bioavailability. The present study was conducted to produce selenium nanoparticles (SeNPs) via a biosynthetic approach using probiotic Bacillus subtilis BSN313 in an economical and easy manner. The BSN313 exhibited a gradual increase in Se reduction and production of SeNPs up to 5–200 µg/mL of its environmental Se. However, the capability was decreased beyond that concentration. The capacity for extracellular SeNP production was evidenced by the emergence of red color, then confirmed by a microscopic approach. Produced SeNPs were purified, freeze-dried, and subsequently characterized systematically using UV–Vis spectroscopy, FTIR, Zetasizer, SEM–EDS, and TEM techniques. SEM–EDS analysis proved the presence of selenium as the foremost constituent of SeNPs. With an average particle size of 530 nm, SeNPs were shown to have a −26.9 (mV) zeta potential and −2.11 µm cm/Vs electrophoretic mobility in water. SeNPs produced during both the 24 and 48 h incubation periods showed good antioxidant activity in terms of DPPH and ABST scavenging action at a concentration of 150 µg/mL with no significant differences (p > 0.05). Moreover, 200 µg/mL of SeNPs showed antibacterial reactivity against Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 9027, and Pseudomonas aeruginosa ATCC 25923. In the future, this work will be helpful to produce biogenic SeNPs using probiotic Bacillus subtilis BSN313 as biofactories, with the potential for safe use in biomedical and nutritional applications.

A total of 180 food borne isolates of methicillin resistant Staphylococcus aureus (MRSA) (oxacillin MICs 864 μg/ml) were used in the present study to investigate the effect of oxacillin on biofilm formation and its detachment process. Majority (98.3%) of these isolates were found to carry icaA gene. Out of 180 isolates 35.5% were identified as MRSA and 64.4% were methicillin sensitive S. aureus (MSSA). Biofilm studies by con-red agar and tube methods revealed that 57% of the MRSA isolates were biofilm producers. Polymerase chain reaction studies suggested that all of the biofilm positive MRSA isolates belong to SCCmec type IV and carry agr type II. This showed the strong association of SCCmec IV agr type II and biofilm formation in food borne MRSA. Conversely, only 13.7% of the MSSA isolates were biofilm positive and majority was found to carry agr type II. It has been noticed that oxacillin has regulatory effect on icaA expression and induce the icaA dependent polysaccharide intracellular adhesin (PIA) production and biofilm formation. This was confirmed by Real Time PCR studies of MRSA and MSSA isolates. Quantitative analysis showed that most of the MRSA isolates started biofilm formation after 24 h of incubation in the presence of sub-inhibitory concentration of oxacillin and achieved highest adhesion on glass slide after 48 h. The control in the absence of oxacillin showed slow conversion from planktonic to biofilm mode of growth (Table 1). Another novel feature of most of these biofilm producing isolates is the reduction in (Optical Density) OD, which is noticed after 48 h of incubation. Possibly, after 48 h oxacillin loses its toxicity or consumed the cells re-adapt to the planktonic state, possibly, by the activation of accessory gene regulator A (agrA) which has an important role in biofilm dispersal.

Selenium nanoparticles (SeNPs) can be produced by biogenic, physical, and chemical processes. The physical and chemical processes have hazardous effects. However, biogenic synthesis (by microorganisms) is an eco-friendly and economical technique that is non-toxic to human and animal health. The mechanism for biogenic SeNPs from microorganisms is still not well understood. Over the past two decades, extensive research has been conducted on the nutritional and therapeutic applications of biogenic SeNPs. The research revealed that biogenic SeNPs are considered novel competitors in the pharmaceutical and food industries, as they have been shown to be virtually non-toxic when used in medical practice and as dietary supplements and release only trace amounts of Se ions when ingested. Various pathogenic and probiotic/nonpathogenic bacteria are used for the biogenic synthesis of SeNPs. However, in the case of biosynthesis by pathogenic bacteria, extraction and purification techniques are required for further useful applications of these biogenic SeNPs. This review focuses on the applications of SeNPs (derived from probiotic/nonpathogenic organisms) as promising anticancer agents. This review describes that SeNPs derived from probiotic/nonpathogenic organisms are considered safe for human consumption. These biogenic SeNPs reduce oxidative stress in the human body and have also been shown to be effective against breast, prostate, lung, liver, and colon cancers. This review provides helpful information on the safe use of biogenic SeNPs and their economic importance for dietary and therapeutic purposes, especially as anticancer agents.

Objective(s): This study was designed to determine the relationship of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli isolates in multispecies biofilms and their individual phenotypic characters in biofilm consortia. Materials and Methods: The subject isolates were recovered from different food samples and identified on the basis of growth on differential and selective media. Tube methods, Congo-red agar method, and scanning electron microscopy (SEM) were used to study biofilms phenotypes. The hydrophobicity of the strains was evaluated by the adhesion to apolar solvent. Results: The results showed that E. coli dominated the pre-biofilm stage. It has been observed that E. coli adopted biofilm life much before S. aureus and P. aeruginosa. However, after adopting biofilm lifestyle, slowly and gradually, P. aeruginosa dominated the consortia and dispersed other stakeholders. The subject isolates of P. aeruginosa produce cis-2-decanoic acid to disperse or inhibit S. aureus and E. coli biofilms. Gas-chromatography and mass spectrometry results showed that cis-2-decanoic was higher in the co-culture condition and increased at late log-phase or at stationary phase. Although majority of S. aureus were unable to compete with P. aeruginosa, however, a minor population competed, survived, and persisted in biofilm consortia as small colony variants. The survivors showed higher expression of sigB and sarA genes. P. aeruginosa showed comparatively higher hydrophobic surface properties. Conclusion: Comparative analysis showed that cell surface hydrophobicity, growth rate, and small colony variants (SCVs) are correlated in biofilm consortia of the P. aeruginosa, S. aureus, and E. coli.

Objective(s):Staphylococcus aureus is a Gram-positive pathogen, well known for its resistance andversatile lifestyle. Under unfavourable conditions, it adapts biofilm mode of growth. For staphylococcal biofilm formation, production of extracellular polymeric substances (EPS) is a pre-requisite, which is regulated by ica operon-encoded enzymes. This study was designed to know the impact of ascorbic acid on biofilm formation and colony spreading processes of S. aureus and MRSA. Materials and Methods: The isolates of methicillin-resistant S. aureus (MRSA) used in present study, were recovered from different food samples. Various selective and differential media were used for identification and confirmation of S. aureus. Agar dilution method was used for determination of oxacillin and ascorbic acid resistance level. MRSA isolates were re-confirmed by E-test and by amplification of mecA gene. Tube methods and Congo-Red agar were used to study biofilm formation processes. Gene expression studies were carried on real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Results: The results revealed the presence of mecA gene belonging to SCCmecA type IV along with agr type II in the isolates. In vitro studies showed the sub-inhibitory concentration of oxacillin induced biofilm production. However, addition of sub-inhibitory dose of ascorbic acid was found to inhibit EPS production, biofilm formation and augment colony spreading on soft agar plates. The inhibition of biofilm formation and augmentation of colony spreading observed with ascorbic acid alone or in combination with oxacillin. Moreover, gene expression studies showed that ascorbic acid increases agr expression and decreases icaA gene expression. Conclusion:The present study concluded thatascorbic acid inhibits biofilm formation, promotes colony spreading and increases agr gene expression in MRSA.

In this article we describe development and validation of stability indicating, accurate, specific, precise and simple Ion-pairing RP-HPLC method for simultaneous determination of paracetamol and cetirizine HCl along with preservatives i.e. propylparaben, and methylparaben in pharmaceutical dosage forms of oral solution and in serum. Acetonitrile: Buffer: Sulfuric Acid (45:55:0.3 v/v/v) was the mobile phase at flow rate 1.0 mL min^-1 using a Hibar^® Lichrosorb^® C₁₈ column and monitored at wavelength of 230nm. The averages of absolute and relative recoveries were found to be 99.3%, 99.5%, 99.8% and 98.7% with correlation coefficient of 0.9977, 0.9998, 0.9984, and 0.9997 for cetirizine HCl, paracetamol, methylparaben and Propylparaben respectively. The limit of quantification and limit of detection were in range of 0.3 to 2.7 ng mL^-1 and 0.1 to 0.8 ng mL^-1 respectively. Under stress conditions of acidic, basic, oxidative, and thermal degradation, maximum degradation was observed in basic and oxidative stress where a significant impact was observed while all drugs were found almost stable in the other conditions. The developed method was validated in accordance with ICH and AOAC guidelines. The proposed method was successfully applied to quantify amount of paracetamol, cetirizine HCl and two most common microbial preservatives in bulk, dosage form and physiological fluid.