Bacterial Cell Surface Hydrophobicity Research Articles

Bradyrhizobium diazoefficiens USDA 110 displays plasticity in the attachment phenotype when grown in different soybean root exudate compounds.

Bradyrhizobium diazoefficiens, a symbiotic nitrogen fixer for soybean, forms nodules after developing a symbiotic association with the root. For this association, bacteria need to move toward and attach to the root. These steps are mediated by the surface and phenotypic cell properties of bacteria and secreted root exudate compounds. Immense work has been carried out on nodule formation and nitrogen fixation, but little is known about the phenotype of these microorganisms under the influence of different root exudate chemical compounds (RECCs) or how this phenotype impacts the root attachment ability. To address this knowledge gap, we studied the impact of 12 different RECCs, one commonly used carbon source, and soil-extracted solubilized organic matter (SESOM) on attachment and attachment-related properties of B. diazoefficiens USDA110. We measured motility-related properties (swimming, swarming, chemotaxis, and flagellar expression), attachment-related properties (surface hydrophobicity, biofilm formation, and attachment to cellulose and soybean roots), and surface polysaccharide properties (colony morphology, exopolysaccharide quantification, lectin binding profile, and lipopolysaccharide profiling). We found that USDA 110 displays a high degree of surface phenotypic plasticity when grown on the various individual RECCs. Some of the RECCs played specific roles in modulating the motility and root attachment processes. Serine increased cell surface hydrophobicity and root and cellulose attachment, with no EPS formed. Gluconate and lactate increased EPS production and biofilm formation, while decreasing hydrophobicity and root attachment, and raffinose and gentisate promoted motility and chemotaxis. The results also indicated that the biofilm formation trait on hydrophilic surfaces (polystyrene) cannot be related to the attachment ability of Bradyrhizobium to the soybean root. Among the tested phenotypic properties, bacterial cell surface hydrophobicity was the one with a significant impact on root attachment ability. We conclude that USDA 110 displays surface plasticity properties and attachment phenotype determined by individual RECCs from the soybean. Conclusions made based on its behavior in standard carbon sources, such as arabinose or mannitol, do not hold for its behavior in soil.

Abstract 4233: The anti-genotoxic function of Lactobacillus species in the context of bile-mediated DNA damage and inflammation in experimental models of GERD

Abstract Lactobacillus species are commensal organisms with probiotic characteristics found in the human oral cavity and gastrointestinal tract. It has been shown that gram-positive organisms, including lactobacilli, make up the majority of the microbiome in the healthy human esophagus. The general consensus is that the microbiome shifts from gram-positive to gram-negative bacteria during gastroesophageal reflux disease (GERD). In patients suffering from GERD, the esophageal tissue is injured by the low pH and bile acids present in the refluxate, resulting in Barrett’s esophagus if untreated. Interestingly, it has been reported that there is a proportional increase in gram-positive lactobacilli within the esophagus during the progression from GERD to Barrett’s esophagus, and finally esophageal adenocarcinoma. To investigate how lactobacilli are able to colonize and survive in a bile-rich environment of the esophagus during GERD, we first exposed three Lactobacillus species (L. acidophilus, L. plantarum, and L. fermentum) to cholate/deoxycholate bile salts or ox-bile as a more physiological model for human reflux. All three species exhibited bile resistance, in addition to bile adaptation after pre-exposure to sub-lethal concentrations. When assessed for changes in bacterial cell surface hydrophobicity, an indicator for bacterial adhesion to various surfaces, both bile types led to an increase of hydrophobicity in L. plantarum and L. fermentum, while L. acidophilus remained high. This provides mechanistic insight into how Lactobacillus species' attachment and colonization remain during reflux-related diseases. Next, we assessed the host-microbe interactions between lactobacilli and esophageal cells and the role these probiotic organisms may have in disease prevention. Acidic bile salts can induce inflammation and DNA damage to esophageal tissue through ROS during GERD, yet we found that the presence of lactobacilli co-cultured with bile-treated esophageal epithelial cells aids in the repair of bile-induced DNA damage in addition to NFKB reductions. To further investigate the host-microbe interactions, we supplemented epithelial cells with lactobacilli postbiotic metabolites and assessed cell viability during 48 hours of growth. Our current preliminary data show that postbiotic supplementation increases cell viability, providing insight into why lactobacilli are present within the normal and diseased human esophagus. This study demonstrates how the colonization of the esophagus during GERD with lactobacilli is based on their adaptability and survival due to changes in hydrophobicity thereby sustaining attachment. Furthermore, the anti-genotoxic and anti-inflammatory effects these organisms exhibit make them of significant interest in the prevention of Barrett’s esophagus and esophageal adenocarcinoma in patients with GERD. Citation Format: Joshua Bernard, Divya Joshi, Claudia Andl. The anti-genotoxic function of Lactobacillus species in the context of bile-mediated DNA damage and inflammation in experimental models of GERD. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4233.

Fish Probiotics: Cell Surface Properties of Fish Intestinal Lactobacilli and Escherichia coli

The properties of intestinal bacteria/probiotics, such as cell surface hydrophobicity (CSH), auto-aggregation, and biofilm formation ability, play an important role in shaping the relationship between the bacteria and the host. The current study aimed to investigate the cell surface properties of fish intestinal bacteria and probiotics. Microbial adhesion to hydrocarbons was tested according to Kos and coauthors. The aggregation abilities of the investigated strains were studied as described by Collado and coauthors. The ability of bacterial isolates to form a biofilm was determined by performing a qualitative analysis using crystal violet staining based on the attachment of bacteria to polystyrene. These studies prove that bacterial cell surface hydrophobicity (CSH) is associated with the growth medium, and the effect of the growth medium on CSH is species-specific and likely also strain-specific. Isolates of intestinal lactobacilli from fish (Salmo ischchan) differed from isolates of non-fish/shrimp origin in the relationship between auto-aggregation and biofilm formation. Average CSH levels for fish lactobacilli and E. coli might were lower compared to those of non-fish origin, which may affect the efficiency of non-fish probiotics use in fisheries due to the peculiarities of the hosts' aquatic lifestyles.

Antibacterial Components and Modes of the Methanol-Phase Extract from Commelina communis Linn.

Infectious diseases caused by pathogenic bacteria severely threaten human health. Traditional Chinese herbs are potential sources of new or alternative medicine. In this study, we analyzed for the first time antibacterial substances in the methanol-phase extract from a traditional Chinese herb-Commelina communis Linn-which showed an inhibition rate of 58.33% against 24 species of common pathogenic bacteria. The extract was further purified using preparative high-performance liquid chromatography (Prep-HPLC), which generated four single fragments (Fragments 1 to 4). The results revealed that Fragment 1 significantly increased bacterial cell surface hydrophobicity and membrane permeability and decreased membrane fluidity, showing disruptive effects on cell integrity of Gram-positive and Gram-negative bacteria, such as Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, and Salmonella enterica subsp., compared to the control groups (p < 0.05). In sum, 65 compounds with known functions in Fragment 1 were identified using liquid chromatography and mass spectrometry (LC-MS), of which quercetin-3-o-glucuronide was predominant (19.35%). Comparative transcriptomic analysis revealed multiple altered metabolic pathways mediated by Fragment 1, such as inhibited ABC transporters, ribosome, citrate cycle and oxidative phosphorylation, and upregulated nitrogen metabolism and purine metabolism, thereby resulting in the repressed bacterial growth and even death (p < 0.05). Overall, the results of this study demonstrate that Fragment 1 from C. communis Linn is a promising candidate against common pathogenic bacteria.

Biodegradation of mixed hydrocarbon and eicosane by novel Enterococcus mundtii SS1 isolated from automobile service station soil

Increasing use of hydrocarbon (HC) in automobiles has made them a threat to the environment. One effective solution to this is biodegradation by indigenous and efficient microorganisms. This study focuses on the biodegradation of mixed real HC i.e., burnt engine oil (BEO) and n-alkane (eicosane) by bacterial isolates from automobile garage soil. Isolates were screened and identified by colony characteristics and 16 s rRNA sequencing. Biodegraded HC was evaluated gravimetrically and by gas chromatography. HC biodegradation can also be correlated with cell growth, biosurfactant production, emulsification index (E24%), pseudo-solubilization, and bacterial cell surface hydrophobicity (CSH). The selected strains were identified as novel Enterococcus mundtii (EM) and well-known Bacillus specie (BS). BEO degradation was 55.15 % and 65.54 % by EM & BS, respectively. Eicosane degradation was 65.17 % and 35.74 % by EM & BS, respectively. These strains were producing biosurfactants i.e., lipoprotein by EM and glycoprotein by BS. E24% with BEO was 43 ± 7 % and 53 ± 10 %; with eicosane was 55 ± 12 % and 48 ± 5 % by EM and BS, respectively. BS showed the highest CSH with BEO and EM with eicosane i.e., 87 % and 82 %, respectively. Results of all the tests collectively support the possibility of efficient bioremediation of BEO by isolates.

The potency of herbal extracts and its green synthesized nanoparticle formulation as antibacterial agents against Streptococcus mutans associated biofilms

This study aims to determine the effects of the extracts of Streblus asper, Cymbopogon citratus, Syzygium aromaticum and its formulation of green synthesized silver nanoparticle (AgNPs) on Streptococcus mutans growth and biofilm formation. The ethanolic extracts of S. asper, C. citratus, S. aromaticum, and a mix of the three herbs demonstrated antibacterial activity against S. mutans isolates by reducing bacterial biofilm formation and decreasing bacterial cell surface hydrophobicity. The formulated AgNPs from the ethanolic extracts could enhance the antibacterial activities of the plant extracts. Molecular docking found the best interaction between luteolin isolated from C. citratus and glucosyltransferase protein (GtfB), assuming the promising anti-biofilm activity. The scanning electron microscopy revealed morphological changes in the biofilm structure and a significant decrease in the biofilm area of the AgNPs treated. The study suggested that the extracts and its application could be used as natural alternative agents with multi-action against S. mutans infections.

In vitro assessment of probiotic properties of Pseudomonas entomophilaCOFCAU_PEP4 isolated from Labeo rohita intestine

AbstractAssessment of beneficial properties by in vitro approaches forms the basis of selection of a potential probiotic. Moreover, bacterial strains of autochthonous origin are considered more useful than strains from allochthonous sources. In this study, a bacterial strain Pseudomonas entomophila COFCAU_PEP4, isolated from the intestine of Indian major carp rohu (Labeo rohita), was evaluated for its probiotic potential using a range of in vitro tests, along with safety assessment. The strain showed antagonistic activity against 12 pathogenic indicator bacteria and tolerance to a wide range of pH (2–9) and bile salt concentrations (up to 10%). The strain also demonstrated significant in vitro adhesion properties, including mucosal adherence, auto‐aggregation capacity, and bacterial cell surface hydrophobicity. Besides being non‐hemolytic, the strain COFCAU_PEP4 was able to produce extracellular enzymes and showed free radical scavenging potential. An experimental challenge study revealed the strain COFCAU_PEP4 as safe for L. rohita. Taken together, the in vitro and safety assessments demonstrated the probiotic potential of the strain P. entomophila COFCAU_PEP4 isolated from an autochthonous source.

Antibacterial Activity and Components of the Methanol-Phase Extract from Rhizomes of Pharmacophagous Plant Alpinia officinarum Hance.

The rhizomes of Alpinia officinarum Hance (known as the smaller galangal) have been used as a traditional medicine for over 1000 years. Nevertheless, little research is available on the bacteriostatic activity of the herb rhizomes. In this study, we employed, for the first time, a chloroform and methanol extraction method to investigate the antibacterial activity and components of the rhizomes of A. officinarum Hance. The results showed that the growth of five species of pathogenic bacteria was significantly inhibited by the galangal methanol-phase extract (GMPE) (p < 0.05). The GMPE treatment changed the bacterial cell surface hydrophobicity, membrane fluidity and/or permeability. Comparative transcriptomic analyses revealed approximately eleven and ten significantly altered metabolic pathways in representative Gram-positive Staphylococcus aureus and Gram-negative Enterobacter sakazakii pathogens, respectively (p < 0.05), demonstrating different antibacterial action modes. The GMPE was separated further using a preparative high-performance liquid chromatography (Prep-HPLC) technique, and approximately 46 and 45 different compounds in two major component fractions (Fractions 1 and 4, respectively) were identified using ultra-HPLC combined with mass spectrometry (UHPLC-MS) techniques. o-Methoxy cinnamaldehyde (40.12%) and p-octopamine (62.64%) were the most abundant compounds in Fractions 1 and 4, respectively. The results of this study provide data for developing natural products from galangal rhizomes against common pathogenic bacteria.

Autoinducer Analogs Can Provide Bactericidal Activity to Macrolides in Pseudomonas aeruginosa through Antibiotic Tolerance Reduction

Macrolide antibiotics are used in treating Pseudomonas aeruginosa chronic biofilm infections despite their unsatisfactory antibacterial activity, because they display several special activities, such as modulation of the bacterial quorum sensing and immunomodulatory effects on the host. In this study, we investigated the effects of the newly synthesized P. aeruginosa quorum-sensing autoinducer analogs (AIA-1, -2) on the activity of azithromycin and clarithromycin against P. aeruginosa. In the killing assay of planktonic cells, AIA-1 and -2 enhanced the bactericidal ability of macrolides against P. aeruginosa PAO1; however, they did not affect the minimum inhibitory concentrations of macrolides. In addition, AIA-1 and -2 considerably improved the killing activity of azithromycin and clarithromycin in biofilm cells. The results indicated that AIA-1 and -2 could affect antibiotic tolerance. Moreover, the results of hydrocarbon adherence and cell membrane permeability assays suggested that AIA-1 and -2 changed bacterial cell surface hydrophobicity and accelerated the outer membrane permeability of the hydrophobic antibiotics such as azithromycin and clarithromycin. Our study demonstrated that the new combination therapy of macrolides and AIA-1 and -2 may improve the therapeutic efficacy of macrolides in the treatment of chronic P. aeruginosa biofilm infections.

Method-induced variation in the bacterial cell surface hydrophobicity MATH test

Bacterial cell surface hydrophobicity is a relevant property in determining the ability of bacteria to adhere to inert surfaces. This property has been measured using the microbial adhesion to hydrocarbon (MATH) test. Several reports in the literature establish the percentage of adhesion to hydrocarbons (PoAtH) value produced by the MATH test for a broad variety of bacteria. Discrepancies in PoAtH values reported for the same strain of a specific microorganism suggest that some method-induced variation may exist, as different research teams employ different versions of the assay. The objective of the present study was to compare the performance of different versions of the MATH test as reported in the literature, to quantify the magnitude of the method-induced variation on PoAtH values. The study demonstrated that PoAtH values are influenced twice as much by variations in the employed assay than by actual differences in cell surface composition or architecture. The two L. reuteri strains studied responded differently to changes in assay conditions showing 40 and 70% method-dependent variation for strain ATCC 53609 and 55730, respectively. These results highlight the need to properly standardize the MATH test to enable comparison of PoAtH values produced by independent research teams.

Lactobacillus acidophilus ve Lactobacillus rhamnosus için Nerium oleander L. Ekstraktının Prebiyotik Olarak Kullanım Olanaklarının Araştırılması

The use of microorganisms that support human health and stimulate the immune system is gaining more importance. It is thought that probiotic bacterial strains, representing a significant portion of these microorganisms, may be treated in different disease groups. For instance, prevention of gastrointestinal diseases, ulcerative colitis, diarrhea, necrotizing enterocolitis, inflammatory bowel diseases, constipation, urogenital system health, rotavirus diarrhea as well as colon cancer can be prevented using probiotics. The probiotic bacterial strains, have basic needs such as bacterial auto-aggregation and cell surface hydrophobicity. Due to the phytochemicals contained in the Nerium oleander L., this plant has been used as medicinal plants. Such plants, when ingested, contact with the human gastrointestinal microbiome, so beneficial microorganisms can be affected. Thus, present study aimed to investigate the effects of Nerium oleander L. extract on two of the most studied and very well-known probiotic bacteria, Lactobacillus acidophilus and Lactobacillus rhamnosus. Nerium oleander L. was extracted using ethanol. Probiotics were grown in the presence of this extract. Surface hydrophobicity of probiotics grown in the presence of plant extract was assessed by Microbial Adhesion to Solvents (MATS) Assay, and auto-aggregation was performed. Auto-aggregation and surface hydrophobicity properties of these bacteria can be modulated by this plant, due to its phytochemicals. Auto-aggregation, as well as surface hydrophobicity were increased or decreased dependent on the dose as the plant extract The combinations of this plant and a probiotic strain could be next generation functional food, defined as food ingredient that has positive health benefits to the human.

A statistical approach for modelling the physical process of bacterial attachment to abiotic surfaces

A statistical approach using a polynomial linear model in combination with a probability distribution model was developed to mathematically represent the process of bacterial attachment and study its mechanism. The linear deterministic model was built based on data from experiments investigating bacterial and substratum surface physico-chemical factors as predictors of attachment. The prediction results were applied to a normal-approximated binomial distribution model to probabilistically predict attachment. The experimental protocol used mixtures of Streptococcus salivarius and Escherichia coli, and mixtures of porous poly(butyl methacrylate-co-ethyl dimethacrylate) and aluminum sec-butoxide coatings, at varying ratios, to allow bacterial attachment to substratum surfaces across a range of physico-chemical properties (including the surface hydrophobicity of bacterial cells and the substratum, the surface charge of the cells and the substratum, the substratum surface roughness and cell size). The model was tested using data from independent experiments. The model indicated that hydrophobic interaction was the most important predictor while reciprocal interactions existed between some of the factors. More importantly, the model established a range for each factor within which the resultant attachment is unpredictable. This model, however, considers bacterial cells as colloidal particles and accounts only for the essential physico-chemical attributes of the bacterial cells and substratum surfaces. It is therefore limited by a lack of consideration of biological and environmental factors. This makes the model applicable only to specific environments and potentially provides a direction to future modelling for different environments.

Investigation of the bacterial cell envelope nanomechanical properties after long-term exposure to nitrofurans

Antibiotic residues in the environment may negatively affect biological communities in the natural ecosystems. However, their influence on environmental bacterial strains has not been thoroughly investigated. In this study, two representatives of 5-nitrofuran antibiotics (nitrofurantoin and furaltadone) were investigated in terms of their long-term influence on the cell envelopes of newly isolated environmental bacterial strains (Sphingobacterium caeni FTD2, Achromobacter xylosoxidans NFZ2 and Pseudomonas hibiscicola FZD2). A 12-month exposure of bacterial cells to nitrofurans at a concentration of 20 mg L−1 induced changes in the cell structure and texture (bacteria under stress conditions showed a loss of their original shape and seemed to be vastly inflated, the cells increased average surface roughness after exposure to NFT and FTD, respectively). AFM observations allowed the calculation of the bacterial cell nanomechanical properties. Significant increase in adhesion energy of bacteria after prolonged contact with nitrofurantoin was demonstrated. Changes in the permeability of bacterial membrane, fatty acids’ composition and bacterial cell surface hydrophobicity were determined. Despite visible bacterial adaptation to nitrofurans, prolonged presence of pharmaceuticals in the environment has led to significant alterations in the cells’ structures which was particularly visible in P. hibiscicola.

Studies on reclamation of crude oil polluted soil by biosurfactant producing Pseudomonas aeruginosa (DKB1)

Abstract One of the primary issues noted worldwide in the marine environment is contamination by crude oil and it's by products. Contrasted with conventional methods, bioremediation offer a possible alternative to remove hydrocarbon pollution from the environment. The present study was undertaken to examine the capability of biosurfactant producing Pseudomonas aeruginosa (DKB1) on recovery of hydrocarbon contaminated soil. Initially Bacterial cell surface hydrophobicity (BATH) of the selected organism towards various hydrocarbons was observed in the following order; hexadecane (91.44%), sunflower oil (83.21%), olive oil (81.86%), hexane (74.78%), toluene (73.99%), diesel (72.60%) and a lower affinity was found against crude oil (46.98%). Further the biosurfactant produced by the candidate strain was extracted and the toxicity effect of the produced biosurfactant was tested against the micro crustacean, brine shrimp Artemia salina nauplii (Cytotoxicity) and the plants like cauliflower, cabbage, rice and green gram (Phytotoxicity). The result revealed that there was no toxicity observed in the tested A. salina and also in the tested plants. The biodegradation efficacy of the potent strain was screened by DCPIP (2, 6- Dichlorophenol indophenol) method using various hydrocarbons (kerosene, benzene, toluene and diesel). The result revealed that the selected organism has high hydrocarbon degrading potential and it turns the medium to become colorless. The crude oil biodegradation by the selected strain was evaluated by gravimetric analysis and also optimized the crude oil degradation potential. Finally the bioremediation of the crude oil contaminated soil was performed in situ laboratory scale experiment using the potent strain and the result indicated that there was up to 63.38% degradation of crude oil after 60 days of incubation. FTIR analysis result of the treated and untreated crude oil was confirmed that the candidate strain has the ability to recover the hydrocarbon polluted environment.

The LuxI/LuxR-Type Quorum Sensing System Regulates Degradation of Polycyclic Aromatic Hydrocarbons via Two Mechanisms.

Members of the Sphingomonadales are renowned for their ability to degrade polycyclic aromatic hydrocarbons (PAHs). However, little is known about the regulatory mechanisms of the degradative pathway. Using cross-feeding bioassay, a functional LuxI/LuxR-type acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) system was identified from Croceicoccus naphthovorans PQ-2, a member of the order Sphingomonadales. Inactivation of the QS system resulted in a significant decrease in PAHs degradation. The QS system positively controlled the expression of three PAH-degrading genes (ahdA1e, xylE and xylG) and a regulatory gene ardR, which are located on the large plasmid. Interestingly, the transcription levels of these three PAH-degrading genes were significantly down-regulated in the ardR mutant. In addition, bacterial cell surface hydrophobicity and cell morphology were altered in the QS-deficient mutant. Therefore, the QS system in strain PQ-2 positively regulates PAH degradation via two mechanisms: (i) by induction of PAH-degrading genes directly and/or indirectly; and (ii) by an increase of bacterial cell surface hydrophobicity. The findings of this study improve our understanding of how the QS system influences the degradation of PAHs, therefore facilitating the development of new strategies for the bioremediation of PAHs.

Unraveling the anti-biofilm potential of green algal sulfated polysaccharides against Salmonella enterica and Vibrio harveyi.

One of the main reasons for the bacterial resistance to antibiotics is caused by biofilm formation of microbial pathogens during bacterial infections. Salmonella enterica and Vibrio harveyi are known to form biofilms and represent a major health concern worldwide, causing human infections responsible for morbidity and mortality. The current study aims to investigate the effect of purified sulfated polysaccharides (SPs) from Chlamydomonas reinhardtii (Cr) on planktonic and biofilm growth of these bacteria. The effect of Cr-SPs on bacterial planktonic growth was assessed by using the agar well diffusion method, which showed clear zones ranging from 13 to 26mm in diameter from 0.5 to 8mg/mL of Cr-SPs against both the bacteria. Time-kill activity and reduction in clonogenic propagation further help to understand the anti-microbial potential of Cr-SPs. The minimum inhibitory concentration of Cr-SPs against S. enterica and V. harveyi was as low as 440μg/mL and 490μg/mL respectively. Cr-SPs inhibited bacterial cell attachment up to 34.65-100% at 0.5-8mg/mL in S. enterica and V. harveyi respectively. Cr-SPs also showed 2-fold decrease in the cell surface hydrophobicity, indicating their potential to prevent bacterial adherence. Interestingly, Cr-SPs efficiently eradicated the preformed biofilms. Increased reduction in total extracellular polysaccharide (EPS) and extracellular DNA (eDNA) content in a dose-dependent manner demonstrates Cr-SPs ability to interact and destroy the bacterial EPS layer. SEM analysisshowed that Cr-SPs effectively distorted preformed biofilms and also induced morphological changes. Furthermore, Cr-SPs also showed anti-quorum-sensing potential by reducing bacterial urease and protease activities. These results indicate the potential of Cr-SPs as an anti-biofilm agent and will help to develop them as alternative therapeutics against biofilm-forming bacterial infections. KEY POINTS: • Cr-SPs not only inhibited biofilm formation but also eradicated preformed biofilms. • Cr-SPs altered bacterial cell surface hydrophobicity preventing biofilm formation. • Cr-SPs efficiently degraded eDNA of the EPS layer disrupting mature biofilms. • Cr-SPs reduced activity of quorum-sensing-mediated enzymes like protease and urease.

Response of Microbes Associated with Internal and External Surfaces of Blattella germanica towards Hydrophobicity and Autoaggregation

German cockroaches (Blattella germanica) are distributed worldwide. Pathogens present on cockroach have always raised safety concerns. Present study aimed to check the bacterial autoaggregation and hydrophobicity potential. Cockroaches were trapped from house sewerage of Lahore, Pakistan in March 2016 and bacteria were isolated from external as well as internal part of cockroach. For isolation from internal colon part of digestive tract were serially diluted and selected (IM1 and IM3) from bacterial growth on agar plates while isolates from external surfaces of cockroach were selected by surface swabbing (EM4, EM5 and EM6). Morphological and biochemical characterization of isolates showed diverse morphology. The auto aggregation was recorded in all isolates after 4 hours of culture incubation. Results of hydrophobicity assay showed that isolates IM1, IM3, EM5 showed 98.09 %, 80.5 %, 90.33 % affinity towards toluene, respectively. Bacteria commonly associated with common pests, cockroaches showed the tendency to adhere to different biotic and abiotic surfaces. Isolate IM3 showed 35 % auto-aggregation after 4 hours while isolate EM4 showed 47 % aggregation as compared to rest of isolates. Result showed that on the basis of bacterial cell surface hydrophobicity and auto aggregation tendency of cells towards adherence and aggregation on host increases.

Blood protein polymorphisms and the gut bacteria: impact of probiotic Lactobacillus acidophilus Narine on Salmonella carriage in sheep.

Related to previous reports on correlations between an animal's genotype, its commensal microbiota, and the ability to resist infections, the aim of the current study was to investigate the associations between sheep genotype and 5-methylcytosine (5-mC) DNA methylation patterns, sheep genotype and cell surface hydrophobicity of sheep gut commensal bacteria. In addition, the effect of the probiotic Lactobacillus acidophilus strain INMIA 9602 Er 317/402 (probiotic formulation Narine) on Salmonella carriage in sheep at Armenian farms was also investigated. Allelotypes and genotypes of different pathogen-sensitive sheep breeds from Armenian farms were studied based on genetic markers of blood transferrin, albumin, and ceruloplasmin. Additionally, the differences between the breeds of Mazekh, Balbas, and Mazekh/Balbas hybrids were reported. The relationship between host sheep blood transferrin and albumin polymorphisms and cell surface hydrophobicity/5-mC DNA methylation patterns from the predominant gut commensal bacteria was shown. The Narine probiotic eliminates Salmonella from the sheep gut microbiota. At the same time, no significant changes in the percentage of 5-mC DNA methylation of predominant gut bacteria after probiotic administration were observed. The evaluation of bacterial cell surface hydrophobicity, the most significant factor affecting bacterial adhesion, as well as 5-mC DNA methylation, might be used for specific sheep husbandry/breeding programs. This study suggests that the commercial probiotic Narine could potentially be used to reduce Salmonella carriage in sheep.

Neutrophil activation by Escherichia coli isolates from human intestine: effects of bacterial hydroperoxidase activity and surface hydrophobicity.

Successful colonization of the intestine requires that bacteria interact with the innate immune system and, in particular, neutrophils. Progression of inflammatory bowel diseases (IBD) is associated with alterations in gut microbiota, and dysbiosis in Crohn’s disease (CD) patients is often associated with an expansion of Escherichia coli. Here, we investigated the ability of such E. coli isolates to avoid neutrophil activation and to utilize reactive oxygen species. Neutrophil activation was detected in vitro in normal human blood via luminol chemiluminescence (CL) induced by reactive oxygen and halogen species generated by neutrophils. No significant difference in neutrophil activation in vitro was detected between isolates from inflamed (23 isolates) vs healthy intestines (5 isolates), with 10‐fold variation within both groups (2.9–61.2 mV). CL activity of isolates from the same patient differed by 1.5–5 times. Twenty‐four isolates from ileal aspirate, biopsy, and feces of seven patients with CD and one patient with no intestine inflammation were tested for extracellular peroxidase and catalase activity and cell surface hydrophobicity. Average values between patients varied from 26 ± 3 to 73 ± 18 µmol·g−1 of air dry weight for peroxidase activity, from 15 ± 2 to 189 ± 56 mmol·g−1 of air dry weight for catalase activity, and from 5 ± 3 to 105 ± 9 a.u. for the hydrophobic probe fluorescence. Extracellular peroxidase activity and hydrophobicity of bacterial cell surface correlated negatively with stimulated neutrophil CL. The ability of some isolates to avoid neutrophil activation and to utilize reactive oxygen species may provide a strategy to survive assault by the innate immune system.

Antimicrobial Activity of Cinnamaldehyde on Streptococcus mutans Biofilms.

Streptococcus mutans is considered the most relevant bacteria in the transition of non-pathogenic commensal oral microbiota to biofilms which contribute to the dental caries process. The present study aimed to evaluate the antimicrobial activity of a natural plant product, cinnamaldehyde against S. mutans biofilms. Minimum inhibitory concentrations (MIC), minimal bactericidal concentration (MBC), and growth curves were determined to assess its antimicrobial effect against planktonic S. mutans. The biofilm biomass and metabolism with different concentrations of cinnamaldehyde and different incubation time points were assessed using the crystal violet and MTT assays. The biofilms were visualized using confocal laser scanning microscopy (CLSM). Bacterial cell surface hydrophobicity, aggregation, acid production, and acid tolerance were evaluated after cinnamaldehyde treatment. The gene expression of virulence-related factors (gtfB, gtfC, gtfD, gbpB, comDE, vicR, ciaH, ldh and relA) was investigated by real-time PCR. The MIC and MBC of cinnamaldehyde against planktonic S. mutans were 1000 and 2000 μg/mL, respectively. The results showed that cinnamaldehyde can decrease biofilm biomass and metabolism at sub-MIC concentrations. CLSM images revealed that the biofilm-covered surface areas decreased with increasing concentrations of cinnamaldehyde. Cinnamaldehyde increased cell surface hydrophobicity, reduced S. mutans aggregation, inhibited acid production, and acid tolerance. Genes expressions in the biofilms were down-regulated in the presence of cinnamaldehyde. Therefore, our data demonstrated that cinnamaldehyde at sub-MIC level suppressed the microbial activity on S. mutans biofilm by modulating hydrophobicity, aggregation, acid production, acid tolerance, and virulence gene expression.