Biofilm Formation Of Microorganisms Research Articles

Microscopic and transcriptomic characterization of Listeria monocytogenes aggregation and biofilm formation in cantaloupe juice

Plant exudate is likely the major nutrient source supporting the survival and biofilm formation of microorganisms in fresh produce processing environments. This study compared the impact of cantaloupe juice on the physiology and gene expression of Listeria monocytogenes (Lm) using microscopic and transcriptomic tools.Lm showed a strong autoaggregation and formed significantly more biofilms on stainless steel (SS) coupons when grown in cantaloupe juice in comparison to in TSB. SEM images revealed a different attachment profile of Lm on SS coupons. In TSB, Lm cells were mainly found in scratches and grooves of the metal surface, whereas, in cantaloupe juice they attached to the smooth surface as well. Lm planktonic and biofilm cells in cantaloupe juice exhibited stress-induced phenotypes, including strong cell elongation and increased proportion of cells with membrane permeability.Lm growth in cantaloupe juice resulted in distinct transcriptional profiles of both biofilm and planktonic cells in comparison to that in TSB. Functional annotation indicated that the significantly differentially expressed genes mainly participated in metabolism, signaling and stress response. Notably, certain pathways downregulated for planktonic cells were significantly upregulated for biofilm cells in cantaloupe juice compared to TSB, including ABC transporters, two-component system, quorum sensing, chemotaxis, and flagellar assembly.

Effect of low concentrations of caffeine and colchicine on microbial growth and biofilm formation

A study into the effect of low concentrations of caffeine and colchicine alkaloids on the growth and biofilm formation of rhizospheric microorganisms – Gram-positive Rhodococcus qingshengii and Gramnegative Rhizobium radiobacter – is presented. Alkaloids present in plants effectively protect them from being eaten by animals of various taxa, as well as from fungal and bacterial infections. Forming part of a complex, evolutionary system of plant-microbial interactions, they occur naturally in the medium at low concentrations. One of the decisive factors in the spread of microorganisms is the formation of biofilms. In the study, alkaloids were added to the bacterial suspension at time intervals corresponding to distinct phases of biofilm formation. In order to determine the level of biofilm formation, bacterial cells were stained with crystal violet. The optical density of the suspension was used to assess the effect of alkaloids on bacterial growth and biofilm formation. The effect of caffeine and colchicine in concentrations of 10-5 g/L on the growth and biofilm formation of microorganisms is revealed for the first time. Although alkaloids did not affect the growth of the suspension of Gram-positive Rhodococcus qingshengii, they effectively suppressed the suspension of Gram-negative Rhizobium radiobacter. While Rhodococcus qingshengii showed greater sensitivity to alkaloids at the stage of biofilm formation, Rhizobium radiobacter was more sensitive at the stage of "mature" biofilms. The effect of alkaloids could be expressed both in terms of suppression and enhancement of biofilm growth. It can be assumed that the mechanism of action of plant alkaloids at the level of signaling systems and bacterial quorum sensing allows the protective function to be maintained even with a significant decrease in the number of alkaloids under conditions of permanent antagonism in which they are constantly being destroyed by phytopathogens.

The microbiome of oral cavity patients with periodontitis, adhesive and biofilm forming properties.

The microbiome of oral cavity in healthy people and patients with periodontitis was analyzed to determine their adhesive properties and the ability to form biofilms. The study involved 2 groups: healthy, 18 people, and an experimental group, 20 patients with chronic generalized periodontitis moderate severity of the disease. The average age of the studied people was 35-45 years. Material - dental plaque, scraping from the mucous membrane of the back of the tongue, the contents of the periodontal groove and periodontal pocket, as well as oral fluid. The main method of diagnostic was bacteriological. The average adhesion index (AAI) was used to determine adhesion level of microorganisms to epithelial cells of oral cavity's mucous membrane. The microbiota's ability to form biofilm was tested on glass and plastic surface. The microbiota of oral cavity of patients with periodontitis was characterized by decrease in the frequency of bacteria of the genera: Streptococcus, Peptostreptococcus, Peptococcus, and an increase in Staphylococcus aureus, Veillonella spp., Bacillus spp. The microbiota of the oral cavity of patients with generalized periodontitis has a greater ability to adhere to the cells of the mucous membrane than in healthy people, while their ability to form biofilms and exhibit pathogenic properties is enhanced. The biofilm formation of microorganisms in healthy and sick people differs both on glass and on plastic surfaces.

Effect of chlorhexidine on oral airway biofilm formation of Staphylococcus epidermidis

Objective: Biofilm formation of microorganisms on the surface of airways may lead to supraglottic colonization that may cause lower respiratuar tract infections. Studies searching the efficiency of local disinfectants on biofilm formation are limited. The aim of this study was to investigate the effects of chlorhexidine coated airways on biofilm formation of Staphylococcus epidermidis. Methods: Culture and electron microscopy methods were used for biofilm assessment. Airways were divided into two groups to investigate the effects of chlorhexidine on number of bacteria attached to the airway and biofilm formation. Group 1(control): naive material, S. epidermidis, Group 2: chlorhexidine coated material, S. epidermidis. No process was applied in Group 1. Chlorhexidine gluconate (0.2%) was sprayed on the surface of naive material for four seconds and then left to dry in air, in Group to. Number of bacteria attached to the airway were counted by microbiological methods and biofilm formation was shown by Scanning Electron Microscope (SEM). Mann-Whitney u test was performed for statistical analyses. Results: In Group 2, bacteria numbers were 1x102-8x102 cfu/ml, whereas they were 3x103-1x104 cfu/ml in Group 1. Chlorhexidine decreased number of microorganisms attached to the airways with statistical significance (p=0.04). The results of the electron microscopic evaluation were in accordance with the bacteriological findings. Conclusion: This study has shown that chlorhexidine coating can successfully reduce the number of adhered bacteria and biofilm formation on airways. J Microbiol Infect Dis 2015;5(4): 162-166 Key words: Chlorhexidine; oral airway; biofilm; Staphylococcus epidermidis

Interspecies Interactions of Metal-Oxidizing Thermo-Acidophilic Archaea <i>Acidianus</i> and <i>Sulfolobus</i>

Biofilm formation of microorganisms on relevant surfaces is of great importance for biomining and acid mine drainage (AMD). Thermo-acidophilic archaea like Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to enhance leaching rates. Visualization and investigation of microbial attachment and biofilm formation of metal-oxidizing organisms up to now has been done mostly with mesophilic or moderately thermophilic bacteria. In this study, attachment and biofilms by the crenarchaeota Sulfolobus metallicus DSM 6482T and a new isolate Acidianus sp. DSM 29099 on sulfur or pyrite were analyzed. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes specific for nucleic acids or glycoconjugates were used to monitor biofilm formation on surfaces. The data indicate that cell attachment and the subsequently formed biofilm structures were species and substrate dependent. The investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. In addition, physical contact between the two species was visible, as revealed by specific lectins able to distinguish single species.

The effects of d-Tyrosine combined with amikacin on the biofilms of Pseudomonas aeruginosa

The biofilm formation of microorganisms causes persistent tissue infections resistant to treatment with antimicrobial agents. Pseudomonas aeruginosa is commonly isolated from the airways of patients with chronic fibrosis (CF) and often forms biofilms, which are extremely hard to eradicate and a major cause of mortality and morbidity. Recent studies have shown that d-amino acids (D-AAs) inhibited and disrupted biofilm formation by causing the release of the protein component of the polymeric matrix. However, the effects of D-AAs combined with common antibiotics on biofilms have rarely been studied. The current study first determined whether D-AAs disrupted the biofilms of PAO1 and the clinical airway isolates of P. aeruginosa. It was then determined whether combinations of D-Tyr (the most effective one) and the antibiotic amikacin (AMK) enhanced the activity against these biofilms. The results of the current study showed that D-Tyr is the most effective among those that disassemble the d-amino acids (d-leucine, d-methionine, D-Tyrptophan, and d-tryptophan), and D-Tyr at concentrations higher than 5 mM significantly reduced the biofilm biomass of P. aeruginosa (p < 0.05) without influencing bacterial growth. It was also revealed that D-Tyr improved the efficacy of AMK to combat P. aeruginosa biofilms, as indicated by a reduction in the minimal biofilm-inhibiting concentration (MBIC50 and MBIC90) without a change in the minimal inhibitory concentration (MIC) of planktonic bacteria. Thus, the findings indicated that D-Tyr supplementation overcame the resistance of P. aeruginosa biofilms to AMK, which might be helpful for preventing AMK overuse when this specific D-Tyr is recommended for combatting these biofilms. Also, toxicity of the liver and kidney from AMK could be potentially mitigated by co-delivery with D-Tyr.

Biofilm infections, their resilience to therapy and innovative treatment strategies

Biofilm formation of microorganisms causes persistent tissue and foreign body infections resistant to treatment with antimicrobial agents. Up to 80% of human bacterial infections are biofilm associated; such infections are most frequently caused by Staphylococcus epidermidis, Pseudomonas aeruginosa, Staphylococcus aureus and Enterobacteria such as Escherichia coli. The accurate diagnosis of biofilm infections is often difficult, which prevents the appropriate choice of treatment. As biofilm infections significantly contribute to patient morbidity and substantial healthcare costs, novel strategies to treat these infections are urgently required. Nucleotide second messengers, c-di-GMP, (p)ppGpp and potentially c-di-AMP, are major regulators of biofilm formation and associated antibiotic tolerance. Consequently, different components of these signalling networks might be appropriate targets for antibiofilm therapy in combination with antibiotic treatment strategies. In addition, cyclic di-nucleotides are microbial-associated molecular patterns with an almost universal presence. Their conserved structures sensed by the eukaryotic host have a widespread effect on the immune system. Thus, cyclic di-nucleotides are also potential immunotherapeutic agents to treat antibiotic-resistant bacterial infections.