Identifying the molecular targets of an anti-pathogenic hydroalcoholic extract of Punica granatum peel against multidrug resistant Serratia marcescens

Background: Antibiotic-resistant members of the family Enterobacteriaceae are among the serious threats to human health globally. This study reports anti-pathogenic activity of Punica granatum peel extract (PGPE) against a multi-drug resistant, beta-lactamase producing member of this family i.e. Serratia marcescens. Objective: This study aimed at assessing anti-pathogenic activity of PGPE against the gram-negative bacterial pathogen S. marcescens, and identifying the molecular targets of this extract in the test bacterium. Methods: Effect of PGPE on S. marcescens growth and quorum sensing (QS)-regulated pigment production was assessed through broth dilution assay. In vivo anti-infective and prophylactic activity of PGPE was assessed employing the nematode worm Caenorhabditis elegans as a model host. Differential gene expression in PGPE-exposed S. marcescens was studied through a whole transcriptome approach. Results: PGPE was able to modulate QS-regulated pigment production in S. marcescens without exerting any heavy growth-inhibitory effect at concentrations as low as ≥2.5 µg/mL. It could attenuate virulence of the test bacterium towards the worm host by 22-42% (p≤0.01) at even lower concentrations (≥0.5 µg/mL). PGPE also exerted a post-extract effect on S. marcescens. This extract was found to offer prophylactic benefit too, to the host worm, as PGPE-pre-fed worms scored better (34-51%; p≤0.001) survival in face of subsequent bacterial attack. Differential gene expression analysis revealed that PGPE affected expression of a total of 66 genes in S. marcescens by ≥1.5 fold. Conclusion: PGPE’s anti-virulence effect against S. marcescens is multifaceted, affecting stress-response machinery, efflux activity, iron homeostasis, and cellular energetics of this bacterium notably. Among the major molecular targets identified in this study are LPS export transporter permease (LptF), t-RNA pseudouridine synthase (TruB), etc.

Investigation on the effect of sonic stimulation onXanthomonas campestrisat the whole transcriptome level

A gram-negative bacteriumXanthomonas campestriswas subjected to sonic stimulation with sound pertaining to 1000 Hz at three different sound intensities. TheX. campestrisculture subjected to sonic stimulation at 66 dB produced 1.69 fold higher exopolysaccharide. Whole transcriptome analysis of this sonic-stimulated culture revealed a total of 115 genes expressed differentially in the sonic-stimulated culture, majority of which were coding for different proteins including enzyme. This study demonstrates the property of the test bacterium of being responsive to sonic/vibrational stimulation.

Study on Limonium aureum Endophytic Fungi and its Antibacterial Activity

Objective To research antibacterial activity of Limonium aureum endophytic fungi. Methods The endophytic fungi of Limonium aureum root was isolated by general method. After incubation, fermentation broth and biomass were extracted by ethyl acetate, n-bothanol and ethanol. The bactefiostatic test was experimented with six different bacterium．The method used was filter paper slice tests. Results 21 endophytes were obtained. After bactefiostatic testing, there were 31 samples with antibaceterial activity against at least one test bacterium he MIC of extraction from E101 and E201 against test bacteria was 0.25mg/mL.

Washing with contaminated bar soap is unlikely to transfer bacteria

SUMMARYRecent reports of the isolation of microorganisms from used soap bars have raised the concern that bacteria may be transferred from contaminated soap bars during handwashing. Since only one study addressing this question has been published, we developed an additional procedure to test this concern. In our new method prewashed and softened commercial deodorant soap bars (0·8% triclocarban) not active against Gram-negative bacteria were inoculated withEscherichia coliandPseudomonas aeruginosato give mean total survival levels of 4·4 × 105c.f.u. per bar which was 70-fold higher than those reported on used soap bars. Sixteen panelists were instructed to wash with the inoculated bars using their normal handwashing procedure. After washing, none of the 16 panelists had detectable levels of either test bacterium on their hands. Thus, the results obtained using our new method were in complete agreement with those obtained with the previously published method even though the two methods differ in a number of procedural aspects. These findings, along with other published reports, show that little hazard exists in routine handwashing with previously used soap bars and support the frequent use of soap and water for handwashing to prevent the spread of disease.