Search results for "030306 microbiology"

Control of the bifunctional O 2 ‐sensor kinase NreB of Staphylococcus carnosus by the nitrate sensor NreA: Switching from kinase to phosphatase state

2019

The NreB-NreC two-component system of Staphylococcus carnosus for O2 sensing cooperates with the accessory nitrate sensor NreA in the NreA-NreB-NreC system for coordinated sensing and regulation of nitrate respiration by O2 and nitrate. ApoNreA (NreA in the absence of nitrate) interacts with NreB and inhibits NreB autophosphorylation (and activation). NreB contains the phosphatase motif DxxxQ. The present study shows that NreB on its own was inactive for the dephosphorylation of the phosphorylated response regulator NreC (NreC-P), but co-incubation with NreB and NreA stimulated NreC-P dephosphorylation. Either the presence of NreA · NO 3 - instead of apoNreA or mutation of the phosphatase m…

Biofilm-detached cells, a transition from a sessile to a planktonic phenotype: a comparative study of adhesion and physiological characteristics in P…

2008

Pseudomonas aeruginosa is a pathogenic bacterium widely investigated for its high incidence in clinical environments and its ability to form strong biofilms. During biofilm development, sessile cells acquire physiological characteristics differentiating them from planktonic cells. But after treatment with disinfectants, or to ensure survival of the species in hostile environments, biofilm cells can detach. This complicates disinfection procedures. This study aimed to physiologically characterize cells detached from a P. aeruginosa biofilm and to compare them with their sessile and planktonic counterparts. We first tested planktonic growth kinetics and capacities to form new biofilms. Then w…

Antibacterial activity of the sponge Suberites domuncula and its primmorphs: potential basis for epibacterial chemical defense

2003

The epibacterial chemical defense of the marine sponge Suberites domuncula was explored by screening sponge extract, sponge primmorph (3-D aggregates containing proliferating cells) extract and sponge-associated as well as primmorph-associated bacteria for antibacterial activ- ity. 16S rDNA sequencing revealed that the antimicrobially active bacteria belonged to the α - and γ- subdivisions of Proteobacteria (α -Proteobacterium MBIC 3368, Idiomarina sp. and Pseudomonas sp., respectively). Moreover, a recombinant perforin-like protein was cloned from S. domuncula that dis- played strong antibacterial activity. Based on these observations, it is proposed that the sponge may be provided with a …

Comparison of growth, acidification and productivity of pure and mixed cultures of Streptococcus salivarius subsp. thermophilus 404 and Lactobacillus…

1994

International audience; Pure and mixed controlled-pH batch cultures of Streptococcus salivarius subsp. thermophilus 404 and Lactobacillus delbrueckii subsp. bulgaricus 398 have been conducted. The characteristics of growth and acidification and the productivity of the cultures were compared. During the mixed cultures, the growth characteristics revealed a pronounced stimulation of S. thermophilus whereas L. bulgaricus metabolism was not significantly improved. The final total population was 1.4 to 4.9 higher than in pure cultures. The acidification characteristics were not enhanced by the mixed culture conditions. The productivity of mixed cultures was 1.7 to 2.4 times higher as compared to…

2019

So far, studies on the bacterial immune system CRISPR-Cas and its ecological and evolutionary effects have been largely limited to laboratory conditions. While providing crucial information on the constituents of CRISPR-Cas, such studies may overlook fundamental components that affect bacterial immunity in natural habitats. Translating laboratory-derived predictions to nature is not a trivial task, owing partly to the instability of natural communities and difficulties in repeated sampling. To this end, we review how aquaculture, the farming of fishes and other aquatic species, may provide suitable semi-natural laboratories for examining the role of CRISPR-Cas in phage/bacterium coevolution…

Detection of Candida albicans biofilm proteins induced by glucose, lactose, soy protein, and iron

2019

Background Oral candidiasis is one of the most common fungal infections, which attack the mucosa of the oral cavity. These lesions are mostly caused by the fungal species Candida albicans. Candida albicans is included in the normal oral microorganisms that are opportunistic pathogens, and its presence is quite large, which can reach 75% of the total oral fungal population. Research on specific proteins of Candida biofilm can be an alternative to early prevention of oral infections such as Oral Candidiasis. This biofilm protein can be used as a reference in making kits to detect the presence of microbes that cause infectious diseases. The purpose of this study was to determine molecular weig…

Selenomethionine labeling of large biological macromolecular complexes: probing the structure of marine bacterial virus PM2.

2008

There is a need for improved tools for labeling protein species within large macromolecular assemblies. Here we describe a method for the efficient selenomethionine labeling of the membrane-containing bacterial virus PM2 for structural studies. By examining potential host cells a strain was found which was auxotrophic for methionine, and by performing a multiparameter search of conditions it was possible to derive a robust protocol which simultaneously minimized the toxic effects of the selenomethionine, so that a reasonable virus yield was maintained, whilst still achieving essentially complete labeling. This has allowed us to fingerprint the protein constituents of the virus in a relative…

Modelling the inhibitory effect of copper sulfate on the growth of Penicillium expansum and Botrytis cinerea

2011

Aims:  This study aimed to investigate the effect of copper sulfate (from 0 to 8 mmol kg−1) on radial growth rate and lag time of two moulds responsible for vine grapes spoilage: Penicillium expansum strain 25·03 and Botrytis cinerea, strains BC1 and BC2. Methods and results:  A new model was developed to describe tailing and shoulders in the inhibition curves. Because of tailing, the minimum inhibitory concentration (MIC), was not defined as the concentration at which no growth was observed, but as the concentration at which the lag time was infinite. The concentrations at which μ = μopt/2, (Cu50), were in the range of 2·2–2·6 mmol kg−1. Radial growth rate of P. expansum and the reciprocal…

“Framboisé” spoilage in French ciders: Zymomonas mobilis implication and characterization

2006

Abstract Biodiversity of 17 Zymomonas mobilis strains isolated from French “framboise” ciders from 7 different geographical areas of France was analysed using random amplified polymorphic DNA (RAPD) and 6 different strain fingerprints were observed. One of the fingerprints was identical for 10 of the 17 cases. No correlation between geographical origin and strain fingerprint was observed. In parallel, the cider-making process was followed from the orchard to the final product for Z. mobilis presence. Detection of the bacterium only occurred during the fermentation process. The French isolate, strain AN0101, recently proposed as a novel subspecies ( Z. mobilis subsp. francensis ) was charact…

Origin of modern syphilis and emergence of a contemporary pandemic cluster

2016

AbstractSyphilis swept across the world in the 16th century as one of most prominent documented pandemics and is re-emerging worldwide despite the availability of effective antibiotics. Little is known about the genetic patterns in current infections or the evolutionary origins of the disease due to the non-cultivable and clonal nature of the causative bacterium Treponema pallidum subsp. pallidum. In this study, we used DNA capture and next generation sequencing to obtain whole genome data from syphilis patient specimens and from treponemes propagated in laboratory settings. Phylogenetic analyses indicate that the syphilis strains examined here share a common ancestor after the 15th century…