sessile cells
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Author(s):  
Franciana Aparecida Volpato Bellaver ◽  
◽  
Anildo Cunha Junior ◽  
Thais Carla Dal Bello ◽  
Ana Julia Longo Neis ◽  
...  

Escherichia coli is a pathogen associated with infections in piglets in the post-weaning phase, its pathogenicity is related to the animal's susceptibility to bacterial enterotoxins. The objective of the present study was to determine the EOs activity against E. coli strain, in the form planktonic and sessile. Although the Disc-Diffusion tests to determine the Minimum Inhibitory Concentration, do not fully corroborate with the other analyzes of this study, it was noticed bacteria inhibition. The EOs were prepared at 0.4%, 0.8% and 1.0% for tests. The tested EOs were effective against E. coli planktonic cells (p<0.05). As for the sessile cells, the most significant result was inhibition and 100% sessile cells at the concentration of 1.0% of Cymbopogon citratus EO. Although there was resistance in some treatments, the tested EOs demonstrated inhibition capacity, constituting promising alternatives for the control of E. coli, especially of planktonic cells.


2021 ◽  
Author(s):  
Itzia S. Gómez-Alonso ◽  
Ilse D. Estrada-Alemán ◽  
Sergio Martínez-García ◽  
Humberto Peralta ◽  
Erika T. Quintana ◽  
...  

Abstract The Staphylococcus aureus’ SdrG protein is glycosylated by SdgA and SdgB for their protection against its degradation by the neutrophil’s cathepsin G. So far, there is not information about the role of Staphylococcus epidermidis’ SdgA nor SdgB in the production of biofilm, therefore the main of this work was to determine the distribution and expression of sdrG, sdgA and sdgB genes in S. epidermidis in conditions of biofilm. The frequency of the genes sdrG, sdgA and sdgB were evaluated by PCR in a collection of 75 isolates. The isolates were grown in dynamic conditions (in agitation) or static conditions (biofilm productor: planktonic or sessile cells). The expression of sdrG, sdgA and sdgB were determined by RT-qPCR in cells grown under dynamic conditions (CGDC), as well as planktonic and sessile cells, and in cells adhered to a catheter (in vivo). The genes sdrG and sdgB were detected in 100% of isolates, meanwhile the gene sdgA was detected in 71% of the samples (p<0.001). The CGDC did not expressed the sdrG, sdgA and sdgB mRNAs. The planktonic and sessile cells expressed sdrG and sdgB, and the same was seen in cells adhered to the catheter. In particular, one isolate, able to induce biofilm under cathepsin G treatment, expressed sdrG and sdgB in planktonic, sessile and in cells adhered to the catheter. This suggests that the state of cells adherence is an important factor for the transcription of sdgA, sdgB and sdrG.


2021 ◽  
Author(s):  
Benedikt K Steinfeld ◽  
Qinna Cui ◽  
Tamara Schmidt ◽  
Ilka B Bischofs

Bacterial populations frequently encounter potentially lethal environmental stress factors. Growing Bacillus subtilis populations are comprised of a mixture of "motile" and "sessile" cells but how this affects population-level fitness under stress is poorly understood. Here, we show that, unlike sessile cells, motile cells are readily killed by monovalent cations under conditions of nutrient deprivation - owing to elevated expression of the lytABC operon, which codes for a cell-wall lytic complex. Forced induction of the operon in sessile cells also causes lysis. We demonstrate that population composition is regulated by the quorum sensing regulator ComA, which can favor either the motile or the sessile state. Specifically social interactions by ComX-pheromone signaling enhance population-level fitness under stress. Our study highlights the importance of characterizing population composition and cellular properties for studies of bacterial physiology and functional genomics. Our findings open new perspectives for understanding the functions of autolysins and collective behaviors that are coordinated by chemical and electrical signals, with implications for multicellular development and biotechnology.


2021 ◽  
Vol 12 ◽  
Author(s):  
Gabriella Maria Andriani ◽  
Ana Elisa Belotto Morguette ◽  
Laís Fernanda Almeida Spoladori ◽  
Patrícia Morais Lopes Pereira ◽  
Weslei Roberto Correia Cabral ◽  
...  

Cryptococcus neoformans is the leading cause of cryptococcosis, an invasive and potentially fatal infectious disease. Therapeutic failures are due to the increase in antifungal resistance, the adverse effects of drugs, and the unavailability of therapeutic regimens in low-income countries, which limit the treatment of cryptococcosis, increasing the morbidity and mortality associated with these infections. Thus, new antifungal drugs and innovative strategies for the cryptococcosis treatment are urgently needed. The aim of the present study was to evaluate the effect of ethyl acetate fraction (EAF) of Poincianella pluviosa stem bark on planktonic and biofilm mode of growth of C. neoformans. Furthermore, the interaction between the EAF and amphotericin B (AmB) was evaluated in vitro and in Galleria mellonella infection model. Minimal inhibitory concentrations (MICs) of EAF ranged from 125.0 to &gt;1,000.0 μg/ml and &gt;1,000.0 μg/ml for planktonic and sessile cells, respectively. The combination between EAF and AmB exhibited a synergistic fungicidal activity toward C. neoformans, with a fractional inhibitory concentration index (FICI) ranging from 0.03 to 0.06 and 0.08 to 0.28 for planktonic and sessile cells, respectively. Microscopy analyses of planktonic C. neoformans cells treated with EAF, alone or combined with AmB, revealed morphological and ultrastructural alterations, including loss of integrity of the cell wall and cell membrane detachment, suggesting leakage of intracellular content, reduction of capsule size, and presence of vacuoles. Moreover, EAF alone or combined with AmB prolonged the survival rate of C. neoformans-infected G. mellonella larvae. These findings indicate that P. pluviosa may be an important source of new compounds that can be used as a fungus-specific adjuvant for the treatment of cryptococcosis.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xingjian Bai ◽  
Dongqi Liu ◽  
Luping Xu ◽  
Shivendra Tenguria ◽  
Rishi Drolia ◽  
...  

AbstractEnvironmental cues promote microbial biofilm formation and physiological and genetic heterogeneity. In food production facilities, biofilms produced by pathogens are a major source for food contamination; however, the pathogenesis of biofilm-isolated sessile cells is not well understood. We investigated the pathogenesis of sessile Listeria monocytogenes (Lm) using cell culture and mouse models. Lm sessile cells express reduced levels of the lap, inlA, hly, prfA, and sigB and show reduced adhesion, invasion, translocation, and cytotoxicity in the cell culture model than the planktonic cells. Oral challenge of C57BL/6 mice with food, clinical, or murinized-InlA (InlAm) strains reveals that at 12 and 24 h post-infection (hpi), Lm burdens are lower in tissues of mice infected with sessile cells than those infected with planktonic cells. However, these differences are negligible at 48 hpi. Besides, the expressions of inlA and lap mRNA in sessile Lm from intestinal content are about 6.0- and 280-fold higher than the sessle inoculum, respectively, suggesting sessile Lm can still upregulate virulence genes shortly after ingestion (12 h). Similarly, exposure to simulated gastric fluid (SGF, pH 3) and intestinal fluid (SIF, pH 7) for 13 h shows equal reduction in sessile and planktonic cell counts, but induces LAP and InlA expression and pathogenic phenotypes. Our data show that the virulence of biofilm-isolated Lm is temporarily attenuated and can be upregulated in mice during the early stage (12–24 hpi) but fully restored at a later stage (48 hpi) of infection. Our study further demonstrates that in vitro cell culture assay is unreliable; therefore, an animal model is essential for studying the pathogenesis of biofilm-isolated bacteria.


2021 ◽  
Vol 9 (2) ◽  
pp. 298
Author(s):  
Nay El-Khoury ◽  
Imene Bennaceur ◽  
Emilie Verplaetse ◽  
Stéphane Aymerich ◽  
Didier Lereclus ◽  
...  

During biofilm growth, the coexistence of planktonic and sessile cells can lead to dynamic exchanges between the two populations. We have monitored the fate of these populations in glass tube assays, where the Bacillus thuringiensis 407 strain produces a floating pellicle. Time-lapse spectrophotometric measurement methods revealed that the planktonic population grew until the pellicle started to be produced. Thereafter, the planktonic population decreased rapidly down to a value close to zero while the biofilm was in continuous growth, showing no dispersal until 120 h of culture. We found that this decrease was induced by the presence of the pellicle, but did not occur when oxygen availability was limited, suggesting that it was independent of cell death or cell sedimentation and that the entire planktonic population has integrated the biofilm. To follow the distribution of recruited planktonic cells within the pellicle, we tagged planktonic cells with GFP and sessile cells with mCherry. Fluorescence binocular microscopy observations revealed that planktonic cells, injected through a 24-h-aged pellicle, were found only in specific areas of the biofilm, where the density of sessile cells was low, showing that spatial heterogeneity can occur between recruited cells and sessile cells in a monospecies biofilm.


2021 ◽  
Vol 12 ◽  
Author(s):  
Constanza Melian ◽  
Patricia Castellano ◽  
Franco Segli ◽  
Lucía M. Mendoza ◽  
Graciela Margarita Vignolo

Listeria monocytogenes is one of the major food-related pathogens and is able to survive and multiply under different stress conditions. Its persistence in industrial premises and foods is partially due to its ability to form biofilm. Thus, as a natural strategy to overcome L. monocytogenes biofilm formation, the treatment with lactocin AL705 using a sublethal dose (20AU/ml) was explored. The effect of the presence of the bacteriocin on the biofilm formation at 10°C of L. monocytogenes FBUNT was evaluated for its proteome and compared to the proteomes of planktonic and sessile cells grown at 10°C in the absence of lactocin. Compared to planktonic cells, adaptation of sessile cells during cold stress involved protein abundance shifts associated with ribosomes function and biogenesis, cell membrane functionality, carbohydrate and amino acid metabolism, and transport. When sessile cells were treated with lactocin AL705, proteins’ up-regulation were mostly related to carbohydrate metabolism and nutrient transport in an attempt to compensate for impaired energy generation caused by bacteriocin interacting with the cytoplasmic membrane. Notably, transport systems such as β-glucosidase IIABC (lmo0027), cellobiose (lmo2763), and trehalose (lmo1255) specific PTS proteins were highly overexpressed. In addition, mannose (lmo0098), a specific PTS protein indicating the adaptive response of sessile cells to the bacteriocin, was downregulated as this PTS system acts as a class IIa bacteriocin receptor. A sublethal dose of lactocin AL705 was able to reduce the biofilm formation in L. monocytogenes FBUNT and this bacteriocin induced adaptation mechanisms in treated sessile cells. These results constitute valuable data related to specific proteins targeting the control of L. monocytogenes biofilm upon bacteriocin treatment.


Foods ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 176
Author(s):  
Francesca Maggio ◽  
Chiara Rossi ◽  
Clemencia Chaves-López ◽  
Annalisa Serio ◽  
Luca Valbonetti ◽  
...  

In dairy processing environments, many bacterial species adhere and form biofilms on surfaces and equipment, leading to foodborne illness and food spoilage. Among them, Listeria monocytogenes and Pseudomonas spp. could be present in mixed-species biofilms. This study aimed to evaluate the interactions between L. monocytogenes and P. fluorescens in biofilms simulating dairy processing conditions, as well as the capability of P. fluorescens in co-culture to produce the blue pigment in a Ricotta-based model system. The biofilm-forming capability of single- and mixed-cultures was evaluated on polystyrene (PS) and stainless steel (SS) surfaces at 12 °C for 168 h. The biofilm biomass was measured, the planktonic and sessile cells and the carbohydrates in biofilms were quantified. The biofilms were also observed through Confocal Laser Scanning Microscopy analysis. Results showed that only P. fluorescens was able to form biofilms on PS. Moreover, in dual-species biofilms at the end of the incubation time (168 h at 12 °C), a lower biomass compared to P. fluorescens mono-species was observed on PS. On SS, the biofilm cell population of L. monocytogenes was higher in the dual-species than in mono-species, particularly after 48 h. Carbohydrates quantity in the dual-species system was higher than in mono-species and was revealed also at 168 h. The production of blue pigment by P. fluorescens was revealed both in single- and co-culture after 72 h of incubation (12 °C). This work highlights the interactions between the two species, under the experimental conditions studied in the present research, which can influence biofilm formation (biomass and sessile cells) but not the capability of P. fluorescens to produce blue pigment.


2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Federica Villa ◽  
Francesco Secundo ◽  
Fabio Forlani ◽  
Cristina Cattò ◽  
Francesca Cappitelli

Abstract Purpose The main goal of the present work was to assess the effectiveness of zosteric acid (ZA) in hindering Escherichia coli biofilm formation on a mineral surface. Methods Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) flow system was used to probe in situ the biochemical changes induced by ZA on E. coli sessile cells growing on the zinc selenide ATR plate. Comparative proteome analysis was conducted on the sessile cells to better understand the principal molecular changes that occur on ZA-treated biofilms. Results The ZA treatment modified the kinetics of the biofilm development. After the ZA exposure, dramatic changes in the carbohydrates, proteins, and DNA profiles were observed over time in the ATR-FTIR spectra. These results were translated into the physiological effects such as the reduction of both the biomass and the EPS contents, the inhibition of the biofilm growth, and the promotion of the detachment. In E. coli sessile cells, the comparative proteome analysis revealed that, while the stress responses were upregulated, the pathways belonging to the DNA replication and repair were downregulated in the ZA-treated biofilms. Conclusions The ZA reduced the binding capability of E. coli cells onto the ZnSe crystal, hindering the firm adhesion and the subsequent biofilm development on a mineral surface. The variation of the protein patterns indicated that the ZA acted as a stress factor on the sessile cells that seemed to discourage biomass proliferation, consequently decreasing the surface colonization.


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