Molecular identification and screening of mushrooms for antibacterial property against Pseudomonas aeruginosa and Staphylococcus aureus

In this study, 18 mushrooms were collected from Gandhi Krishi Vigyana Kendra (GKVK) campus, University of Agricultural Sciences, Bangalore (India) and identified by Internal Transcribed Spacer (ITS) region using National Centre for Biotechnology Information (NCBI) data base and screened for antibacterial property against two skin infection causing bacteria viz.,Pseudomonas aeruginosa and Staphylococcus aureus in dogs. Eleven mushrooms extract inhibited both the bacteria showing their antimicrobials as broad spectrum while inhibiting gram positive as well as gram negative bacteria.  The highest zone of inhibition was recorded from the extract of Lyophyllum sp. The extract of two mushrooms viz., Phlebopus portentosus and Termitomyces sp. inhibited only P. aeruginosa, a gram negative bacterium  and the extract of three mushrooms viz., Agaricus sp, Coprinellus disseminates and Agaricus blazei inhibited only S. aureus, a gram positive bacterium, suggesting spectral specificity of their antimicrobial compounds.  However,  the extracts of two mushrooms viz.,Macrocybe gigantea and Schizophyllum commune did not show inhibition of any of the pathogens.  Hence, this study suggests that the occurrence of potential pharmaceuticals in mushrooms can be exploited for control of multidrug resistant bacteria

Bacillus cereus nositelj plazmida pXO1 s genom pag uzrokuje u goveda s oslabljenim imunosnim sustavom smrtonosnu septikemiju sličnu bedrenici - kratko priopćenje.

Bacillus cereus is ubiquitous in nature and while most isolates appear to be harmless, some are associated with food-borne illnesses, wound infections, endocarditis, osteomyelitis, endophthalmitis and urinary tract infections in humans. Recently, a few isolates have been identified as the causative agents of anthrax-like severe pneumonia in humans, and these isolates were found to harbor most of the B. anthracis virulence plasmid pXO1. Here we report the characterization of three clinical B. cereus isolates recovered from heart blood and spleen samples of cattle which had died with ‘anthrax like’ symptoms. Apart from the cultural characterizations, primers targeting the 16S rRNA gene of B. cereus were designed and used on these isolates. The isolates were found to harbor the pXO1 plasmid and lacked pXO2 plasmid. Further characterization of the pXO1 plasmid revealed that the isolates contained pag, lef and cya genes, which code for protective antigen, lethal factor and edema factor toxins responsible for eliciting an ‘anthrax like disease’ in cattle. The sequencing and phylogenetic analysis of partial pag gene sequences of B. cereus isolates were identical to pag gene sequences on the pXO1 of B. anthracis. In a pathogenicity test on mice, B. cereus isolates, when inoculated by the intra peritoneal route, caused mortality of the mice within 6 hours post inoculation.Bacillus cereus je posvudašnja bakterija. Većina izolata te bakterije je neškodljiva, a neki mogu uzrokovati bolesti koje se prenose hranom, infekcije rana, endokarditis, osteomijelitis, endoftalmitis i infekcije mokraćnog sustava u ljudi. Nedavno je identificirano nekoliko izolata koji uzrokuju tešku upalu pluća u čovjeka sličnu onoj kod bedrenice. Ti izolati većinom nose virulentni plazmid pXO1 vrste B. anthracis. U ovom radu određena su obilježja triju kliničkih izolata vrste B. cereus izdvojenih iz krvi sadržane u srcu i uzoraka slezene goveda uginulih pod znakovima sličnima bedrenici. Osim određivanja kulturalnih obilježja, pripremljene su i početnice za gen 16S rRNA vrste B. cereus koje su bile rabljene za identifikaciju izolata. Ustanovljeno je da izolati nose plazmid pXO1, a nedostaje im plazmid pXO2. Daljnja karakterizacija plazmida pXO1 pokazala je da izolati sadrže gene pag, lef i cya koji kodiraju za zaštitni antigen, letalni čimbenik i edemski čimbenik, toksine koji su odgovorni za pojavu bolesti u goveda slične bedrenici. Određivanje slijeda i filogenetska analiza dijela sekvencija gena pag izolata B. cereus pokazala je da su oni istovjetni sekvencijama gena pag na pXO1 bakterije B. anthracis. U testu patogenosti na miševima, izolati B. cereus prouzročili su njihovo uginuće šest sati nakon intraperitonejske inokulacije

Equilibrium unfolding studies of monellin: the double-chain variant appears to be more stable than the single-chain variant

To improve our understanding of the contributions of different stabilizing interactions to protein stability, including that of residual structure in the unfolded state, the small sweet protein monellin has been studied in both its two variant forms, the naturally occurring double-chain variant (dcMN) and the artificially created single-chain variant (scMN). Equilibrium guanidine hydrochloride-induced unfolding studies at pH 7 show that the standard free energy of unfolding, ΔG°<SUB>U</SUB>, of dcMN to unfolded chains A and B and its dependence on guanidine hydrochloride (GdnHCl) concentration are both independent of protein concentration, while the midpoint of unfolding has an exponential dependence on protein concentration. Hence, the unfolding of dcMN like that of scMN can be described as two-state unfolding. The free energy of dissociation, ΔG°<SUB>d</SUB>, of the two free chains, A and B, from dcMN, as measured by equilibrium binding studies, is significantly lower than Δ G°<SUB>U</SUB>, apparently because of the presence of residual structure in free chain B. The value of ΔG°<SUB>U</SUB>, at the standard concentration of 1 M, is found to be ~5.5 kcal mol<SUP>−1</SUP> higher for dcMN than for scMN in the range from pH 4 to 9, over which unfolding appears to be two-state. Hence, dcMN appears to be more stable than scMN. It seems that unfolded scMN is stabilized by residual structure that is absent in unfolded dcMN and/or that native scMN is destabilized by strain that is relieved in native dcMN. The value of ΔG°<SUB>U</SUB> for both protein variants decreases with an increase in pH from 4 to 9, apparently because of the thermodynamic coupling of unfolding to the protonation of a buried carboxylate side chain whose pK<SUB>a</SUB> shifts from 4.5 in the unfolded state to 9 in the native state. Finally, it is shown that although the thermodynamic stabilities of dcMN and scMN are very different, their kinetic stabilities with respect to unfolding in GdnHCl are very similar