Investigation of the physiology and architecture of Salmonella Enteritidis biofilms under alkaline conditions

Formation of bacterial biοfilms is an important survival strategy in multiple adverse environments. It is often affected by the nature of the attachment surface, the bacterial strain and the surrounding physicochemical conditions. The effect of low pH on biofilm formation has been well studied, in contrast to the alkaline range. The aim of this project was tο study the effect of alkaline stress on the formation οf biοfilm by Salmonella enteritidis and to examine the biofilm architecture patterns under different conditions, by use of confocal microscopy. The optimal pH for Salmonella biofilm formation was found to be pH 7.0, while pH 10.0 (adjusted by use of sodium hydroxide) reduces it significantly (p-value = 0.015). Planktonic cell growth was hindered due to the alkaline pH, yet the number of viable cells remained high. In addition, the effect on biofilm formation was stronger when the alkaline stimulus was applied during stationary phase (9 h after inoculation). When the pH was adjusted to 10 by use of a commercial alkaline detergent (sodium carbonate or washing soda) similar results were observed. Finally, the biofilm architecture at pH 7.0 was characterized by small cell clusters, whereas at pH 10.0 a slightly thinner layer of individual cells was observed. These findings indicate that although most cells survive the alkaline stress, their ability to form biofilm is impaired at alkaline pH, potentially leading to new disinfectant strategies involving alkaline reagents

In Silico Genomic and Metabolic Atlas of Limosilactobacillus reuteri DSM 20016: An Insight into Human Health

Probiotics are bacterial strains that are known to provide host health benefits. Limosilacto-bacillus reuteri is a well-documented lactic acid bacterium that has been cultured from numerous human sites. The strain investigated was L. reuteri DSM 20016, which has been found to produce useful metabolites. The strain was explored using genomic and proteomic tools, manual searches, and databases, including KEGG, STRING, BLAST Sequence Similarity Search, and UniProt. This study located over 200 key genes that were involved in human health benefit pathways. L. reuteri DSM 20016 has metabolic pathways to produce acetate, propionate, and lactate, and there is evidence of a pathway for butanoate production through a FASII mechanism. The bacterium produces histamine through the hdc operon, which may be able to suppress proinflammatory TNF, and the bacterium also has the ability to synthesize folate and riboflavin, although whether they are secreted is yet to be explored. The strain can bind to human Caco2 cells through srtA, mapA/cnb, msrB, and fbpA and can compete against enteric bacteria using reuterin, which is an antimicrobial that induces oxidative stress. The atlas could be used for designing metabolic engineering approaches to improve beneficial metabolite biosynthesis and better probiotic-based cures

Microbes Against Humanity, a workshop game for horrible students: using a creative card game in higher education microbiology teaching

Introducing creative workshops in higher education curricula, in addition to formal lectures, is an excellent way of reinforcing knowledge and encouraging creative thinking. In particular, the use of card games as a tool for inducing student engagement and enthusiasm has been reported to be a very effective approach. Here, we report an innovative card game-based workshop for use at the intermediate undergraduate level. The name of the game is Microbes Against Humanity and has been adapted from the widely known party game Cards Against Humanity, which is freely available under a creative commons licence. Overall, 64 students and two academics participated in this 2 h workshop. Our students found the workshop to be very enjoyable, considered it to be helpful for their learning and suggested interesting ideas for further improvement. In conclusion, it was shown that such exciting workshops can trigger students’ enthusiasm for microbiology and enhance their learning potential

Multi-dimensional experimental and computational exploration of metabolism pinpoints complex probiotic interactions

Multi-strain probiotics are widely regarded as effective products for improving gut microbiota stability and host health, providing advantages over single-strain probiotics. However, in general, it is unclear to what extent different strains would cooperate or compete for resources, and how the establishment of a common biofilm microenvironment could influence their interactions. In this work, we develop an integrative experimental and computational approach to comprehensively assess the metabolic functionality and interactions of probiotics across growth conditions. Our approach combines co-culture assays with genome-scale modelling of metabolism and multivariate data analysis, thus exploiting complementary data- and knowledge-driven systems biology techniques. To show the advantages of the proposed approach, we apply it to the study of the interactions between two widely used probiotic strains of Lactobacillus reuteri and Saccharomyces boulardii, characterising their production potential for compounds that can be beneficial to human health. Our results show that these strains can establish a mixed cooperative-antagonistic interaction best explained by competition for shared resources, with an increased individual exchange but an often decreased net production of amino acids and short-chain fatty acids. Overall, our work provides a strategy that can be used to explore microbial metabolic fingerprints of biotechnological interest, capable of capturing multifaceted equilibria even in simple microbial consortia

Olive Pomace Oil can be Used as an Alternative Carbon Source for Clavulanic Acid Production by Streptomyces clavuligerus

Clavulanic acid is an important drug, both medically and economically. It is used to combat bacterial resistance to β-lactam antibiotics and is on the World Health Organisation’s List of Essential Medicines in combination with amoxicillin. An olive oil industry waste product, olive pomace oil (OPO), is a potential alternative carbon source for clavulanic acid production by Streptomyces clavuligerus. OPO is six times cheaper than glycerol, which is the current industry standard. The aims of this study were to examine if OPO can be used as a carbon source for clavulanic acid production and to compare the clavulanic acid yield achieved in shake flasks and 1.8 L bioreactors. It was observed that OPO was efficiently utilised as a sole carbon source by S. clavuligerus growing in a P-limited medium. The S. clavuligerus cells grew faster in OPO-containing cultures compared to the glycerol-containing cultures (control) and produced comparable levels of clavulanic acid, but much earlier. In cultures with ISP2 medium that contained glycerol or OPO, higher levels of clavulanic acid were obtained in shake flask cultures with OPO. Interestingly, the same levels of clavulanic acid were observed in oil-containing cultures in bioreactors, but 48 h earlier. Furthermore, the oil-containing cultures did not need addition of an antifoam agent, while higher levels of cell viability were maintained after 72 h in these fermentations compared to the cultures that contained glycerol. Our results suggest that OPO can replace glycerol for clavulanic acid production in S. clavuligerus fermentations, which will significantly increase the productivity and cut the cost for industrial clavulanic acid biosynthesis. The same carbon source can be tested in other similar fermentation approaches for the production of antibiotics or other valuable bioproducts

A strong inhibitory effect of heather honey, propolis and medicinal plant extracts on biofilm formation by pathogenic bacteria

Introduction: P. aeruginosa and S. aureus are opportunistic pathogens that cause a wide range of infections. Their increasing resistance to antibiotics is a serious concern and making them susceptible to treatments is now more essential than ever. There is a need to discover new biofilm inhibitors to increase the susceptibility of these bacteria to antibiotics. Hypothesis and aims: To evaluate the antibiofilm activity of heather honey, propolis and medicinal plant extracts against P. aeruginosa and S. aureus. Methodology: Determination of optimum biofilm growth was carried out using a time-course assay over 24 h intervals, using P. aeruginosa PA14 and S. aureus NCTC 4135 strains. The inhibitory effects of all extracts were determined by biofilm inhibition assay in 24-well plates, with biofilms stained with crystal violet and de-stained with ethanol:acetone; OD were measured at 550 nm. Planktonic growth was measured at 600 nm and samples from the wells were streaked to determine bactericidal effects. Results: Heather honey extracts inhibited both P. aeruginosa and S. aureus by 68%. At 60 μg/mL, one of the propolis extracts promoted biofilm growth of both pathogens. Two other propolis extracts also promoted growth in P. aeruginosa but inhibited biofilm formation in S. aureus by 76.5% and 13.8%, respectively. Three plant extracts inhibited S. aureus biofilm by 7.5%, 10.2% and 87.6% and inhibited P. aeruginosa by −34.9%, 34.7% and 19.4%, respectively. Conclusion: All samples showed varying biofilm inhibition capabilities, but biofilm formation seemed to be more easily inhibited in S. aureus than in P. aeruginosa

Transcriptomic Adjustments of Staphylococcus aureus COL (MRSA) Forming Biofilms Under Acidic and Alkaline Conditions

© Copyright © 2019 Efthimiou, Tsiamis, Typas and Pappas. Methicillin-resistant Staphylococcus aureus (MRSA) strains are important human pathogens and a significant health hazard for hospitals and the food industry. They are resistant to β-lactam antibiotics including methicillin and extremely difficult to treat. In this study, we show that the Staphylococcus aureus COL (MRSA) strain, with a known complete genome, can easily survive and grow under acidic and alkaline conditions (pH5 and pH9, respectively), both planktonically and as a biofilm. A microarray-based analysis of both planktonic and biofilm cells was performed under acidic and alkaline conditions showing that several genes are up- or down-regulated under different environmental conditions and growth modes. These genes were coding for transcription regulators, ion transporters, cell wall biosynthetic enzymes, autolytic enzymes, adhesion proteins and antibiotic resistance factors, most of which are associated with biofilm formation. These results will facilitate a better understanding of the physiological adjustments occurring in biofilm-associated S. aureus COL cells growing in acidic or alkaline environments, which will enable the development of new efficient treatment or disinfection strategies

Grounding the Simulation of Iconic Gestures in Gesture Typology

Bergmann K, Kopp S, Rieser H. Grounding the Simulation of Iconic Gestures in Gesture Typology. In: Efthimiou E, Kouroupetroglou G, eds. Proceedings of the 9th International Gesture Workshop: Gestures in Embodied Communication and Human-Computer Interaction. Berlin/Heidelberg, Germany: Springer; 2011: 33-36

Spontaneous expulsion from rectum: a rare presentation of intestinal lipomas

Lipomas are rare, subserosal, usually solitary, pedunculated small lesions appearing mainly in the large intestine with a minimal malignancy potential. They usually run asymptomatic and become symptomatic when they become enlarged or complicated causing intestinal obstruction, perforation, intusucception or massive bleeding. In rare cases they can be self-detached and expulsed via the rectum as fleshy masses. This event mainly occurs in large, pendunculated lipomas which detach from their pedicle. The reason for this event remains in most of cases unclear although in some cases a predisposing factor does exist. Abdominal pain and obstructive ileus may be observed while in many cases bleeding occurs. The expulsed mass sets the diagnosis and in most of the cases all symptoms subside. Diagnosis is rarely established before surgery with the use of barium enema, computed tomography and colonoscopy which additionally provides measures of treatment and diagnosis. In atypical cases though, in cases where the malignancy can not be excluded or in complicated cases, surgery is recommended. Usually the resection of the affected intestinal part is adequate. If during surgery a lipoma is encountered simple lipomatectomy seems also to be adequate