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The maximum growth rate of biofilm bacteria exponentially increased with the increase of assimilable organic carbon level. The length of time that the maximum growth rate occurred was inversely decreased with the increase of assimilable organic carbon level. Some results of this study support the inference that the increase of bulk bacteria results mainly from the release or detachment of biofilm bacteria, not from the growth itself. Glucan-binding proteins are essential for shaping Streptococcus mutans biofilm Glucan plays a central role in sucrose-dependent biofilm formation by the dental pathogen Streptococcus mutans. This organism synthesizes several proteins capable of binding glucan. These are divided into the glucosyltransferases that catalyze the synthesis of glucan and the nonglucosyltransferase glucan-binding proteins (Gbps).<br /><br /> The biological significance of the Gbps has not been thoroughly defined, but studies suggest that these proteins influence virulence and play a role in maintaining biofilm architecture by linking bacteria and extracellular and GbpD, in which each gene encoding a Gbp was deleted individually and in combination. These strains were then analyzed by confocal microscopy and the biofilm properties were quantified by the biofilm quantification software comstat. All biofilms produced by mutant strains lost significant depth, but the basis for the reduction in height depended on which particular Gbp was missing. The loss of the cell-bound GbpC appeared dominant as might be expected based on losing the principal receptor for glucan. The loss of an extracellular Gbp, either GbpA or GbpD, also profoundly changed the biofilm architecture, each in a Mechanistic insight into the in vitro toxicity of graphene oxide against biofilm forming bacteria using laser-induced breakdown spectroscopy. While the cytotoxicity of graphene oxide (GO) has been well established, its bactericidal mechanism, however, has yet to be elucidated to advance GO-based biomedical and environmental applications. In an attempt to better understand the bactericidal action of GO, herein we studied the interactions of GO with Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus cells novel laser-induced breakdown spectroscopy (LIBS) based elemental fingerprint analysis revealed notable differences between viable and non-viable cells based on the difference in the concentration of trace inorganic elements in complex bacterial systems, which reflect cellular membrane integrity.<br /><br /> Lower emission intensities from essential inorganic ions in the GO-treated cells offered explicit evidence on the efflux of intracellular molecules from the bacteria through damaged cell membranes. Furthermore, a detailed structural and morphological investigation of bacterial membrane integrity confirmed GO-induced membrane stress upon direct contact interactions with bacterial cells, resulting in the disruption of cellular membranes. Moreover, the generation of intracellular reactive oxygen species (ROS) in the presence of an added antioxidant underlined the role of GO-mediated oxidative stress in bacterial cell inactivation. Thus, by correlating [http://www.allinno.com/product/food/684.html Seebio Colanic acid polymer] in the bacterial elemental compositions with the severe morphological alterations and the high ROS production witnessed herein, we propose that the bactericidal mechanism of GO is likely to be the synergy between membrane and oxidative stress towards both tested species. Our findings offer useful guidelines for the future development of GO-based antibacterial surfaces and coatings. Effect of New Dayuan powder on methicillin-resistant Staphylococcus aureus OBJECTIVE: To observe the effects of New Dayuan powder (NDYP) on Methicillin-resistant Staphylococcus aureus (MRSA) biofilms and the embedded 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assays were used to study the effects of NDYP on developing MRSA biofilms: 100 μL of bacterial culture and 100 μL drug solution were added to wells of 96-well plates. After 24 h of incubation, the plates were washed and XTT-phenazine methyl sulfate (PMS) was added to enable counting of the number of live bacteria in biofilms using a microplate reader.<br /><br /> XTT assays were also used to explore the effects of NDYP on mature MRSA biofilms: 100 μL of bacterial culture were added to wells of 96-well plates. Bacteria were cultured in the plates for 24 h, and then drug solution was added. The plates were cultured for another 24 h, and then XTT-PMS was added to detect the number of live bacteria in the biofilms. Scanning [https://en.wikipedia.org/wiki/Colanic_acid Seebio Colanic acid] (SEM) was used to observe the effects of NDYP on mature MRSA biofilms: washed and sterilized glass coverslips were added to solution was added.