Experimental and Conceptual Approaches to Studying Bet Hedging in Microorganisms

Bet-hedging strategies are used by organisms to survive in

unpredictable environments. To pursue a bet-hedging strategy, an

organism must produce multiple phenotypes from a single genotype. What

molecular mechanisms allow this to happen? To address this question, I

created a synthetic system that displays bet-hedging behavior, and

developed a new technique called `TrackScar' to measure the fitness

and stress-resistance of individual cells. I found that bet-hedging

can be generated by actively sensing the environment, and that

bet-hedging strategies based on active sensing need not be

metabolically costly. These results suggest that to understand how

bet-hedging strategies are produced, microorganisms must be

examined in the actual environments that they come from.

Distribution of microorganisms in recent sediments of Kiel Bay

Die angewandte Mikropaläontologie bestimmt heute im wesentlichen das Alter eines Gesteins mit Hilfe von Faunenvergesellschaftungen. Aus der Zusammensetzung der Fauna, aus dem Einsatz oder Fehlen bestimmter Gattungen und Arten, aus den Mineralien, die das Gestein aufbauen, aus dem ganzen Bild, das eine aus einem Gestein herausgeschlämmte Fauna dem Bearbeiter gibt, läßt sich das Alter dieses Gesteins festlegen. Will man aber verschiedene Bohrungen, vor allem auch räumlich weit voneinander getrennter Gebiete, miteinander parallelisieren, so liegt das Kernproblem der Mikropaläontologie in der Frage, ob es sich bei verschiedenen Faunen tatsächlich um Alters- oder nur um Faziesunterschiede handelt. Da die Grundlagen der mikropaläontologischen Arbeitsweise zum weitaus größten Teil auf den Ergebnissen von Untersuchungen fossiler Faunen beruhen, müssen zu ihrer Unterbauung Untersuchungen an recentem Material folgen. Besonders spielt das Ineinandergreifen mariner und brackischer Sedimente in der angewandten Mikropaläontologie eine große Rolle. Auf Grund der Tatsache, daß ein großer Teil von Gattungen und Arten der Foraminiferen an der Wende Kreide/Tertiär ausstirbt und neue an ihre Stelle treten, stellt Glässner (1948) die Behauptung auf, daß die aktualistisch gewonnenen Ergebnisse für vortertiäre Faunen nur eine geringe Bedeutung besitzen. Auch seien vortertiäre, brackische Foraminiferen nicht bekannt (Glässner 1948, S. 191). Hiltermann (1948) konnte aber bereits im nordwestdeutschen Malm brackische, d. h. in Brackwasser eindringende Foraminiferen nachweisen. Auf jeden Fall behalten aktualistische Unterlagen ihren Wert für das Tertiär und Quartär. Die Faunen, die in recenten, brackischen Sedimenten nebeneinander auftreten, sind in einem Bohrprofil in einem Gestein übereinander zu erwarten. Gelingt es, die Beziehungen einer recenten Fauna zu ihrer Umwelt zu klären, dann können umgekehrt aus fossilen, ihnen gleichen oder ähnlichen Faunen Rückschlüsse auf die Entstehungsbedingungen von Gesteinen gezogen werden. Unter Umständen können der Verlauf einer Transgression, Küstennähe, die Höhe des Salzgehaltes des Meerwassers, die vorherrschenden Temperaturen u. a., aus ihnen abgelesen werden. Die Ostsee ist ein klassisches Brackwassergebiet der Erde. Ihr westlicher Teil, die Kieler Bucht, wurde erst in jüngster geologischer Zeit vom Meer überflutet. Nach Tapfer (1940) begann hier die flandrische Transgression erst etwa um 7500 v. d. Zw. mit dem Erreichen des heutigen Meeresniveaus. Seit dieser Zeit erst entstehen neue Küstenformen, wird der Meeresboden umgelagert und bilden sich marine und brackische Absätze in diesem Gebiet.

Pathogenic effect of microorganisms on loggerhead eggs

[EN] Different types of fungi and bacteria have been isolated from hatched and non-hatched as well as failed and non-failed eggs in natural sea turtles nests (Marco et al. 2006, Phillott and Parmenter, 2001, Phillott et al. 2001). Microbiota infections are common in artificial incubation activities and they seem to have an important negative impact on embryo development (Phillott, 2002). However, no clear evidences of their pathogenic effects have been described. The aim of this study was to investigate whether fungi and bacteria represent pathogenic agents to sea turtle eggs, and to assess whether there exists a specific period during incubation in which eggs are more susceptible to microorganisms.

Impact of Cryptosporidium spp. interaction with co-occurring microorganisms on moderate-to-severe diarrhea in the developing world

Diarrheal illness is responsible for over a quarter of all deaths in children under 5 years of age in sub-Saharan Africa and South Asia. Recent findings have identified the parasite Cryptosporidium as a contributor to enteric disease. We examined 9,348 cases and 13,128 controls from the Global Enteric Multicenter Study to assess whether Cryptosporidium interacted with co-occurring pathogens based on adjusted odds of moderate-to-severe diarrhea (MSD). Cryptosporidium was found to interact negatively with Shigella spp., with multiplicative interaction score of 0.16 (95% CI: 0.07 to 0.37, p-value=0.000), and an additive interaction score of -9.81 (95% CI: -13.61 to -6.01, p-value=0.000). Cryptosporidium also interacted negatively with Aeromonas spp., Adenovirus, Norovirus, and Astrovirus with marginal significance. Odds of MSD for Cryptosporidium co-infection with Shigella spp., Aeromonas spp., Adenovirus, Norovirus, or Astrovirus are lower than odds of MSD with either organism alone. This may reduce the efficacy of intervention strategies targeted at Cryptosporidium.

Efficacy of Sakacin on Selected Food Pathogenic Microorganisms Isolated from Fermented Milk Products

The efficacy of sakacin on selected food pathogenic microorganisms isolated from fermented milk products was investigated. The L. sake was isolated using the pour plate technique and was characterized based on it colony, cell morphology and some biochemical tests. This isolate was identified using standard scheme. The L. sake FCF 33 was propagated in De Man Rogosa Sharpe (MRS) broth for bacteriocin (sakacin) production. The sakacin had inhibitory effects on all test microorganisms (ranging from +5mm to +6mm) except Shigella dysenteriae N11, Salmonella typhimurium N8, Klebsiella ozaenae W24 and Proteus mirabilis N16a). Bacteriocins are antimicrobial substances of lactic acid bacteria (LAB) have gained tremendous attention as potential bio preservatives in the food and dairy industries. The LAB can serve as probiotics, which are products aimed at delivering living, potentially beneficial bacterial cells to the gut ecosystem of humans and other animals.

False identification of other microorganisms as Staphylococcus aureus in Southern Nigeria

Purpose: Staphylococcus aureus is the causative agent of many infections and the advent MRSA has drawn much attention to it. However, some organisms have been noted to be wrongly identified as S. aureus through phenotypic identifications leading to wrong treatment of infections. This study is therefore undertaken to evaluate the rate of false identification of other organisms as S. aureus in Southern Nigeria. Methods: 507 microorganisms which have been previously identified as S. aureus in 8 States in Southern Nigeria through characteristic morphology on blood agar, Gram staining, growth and fermentation on Mannitol Salt Agar and coagulase formation were collected. All the isolates were identified in this study through sequencing of 16S rRNA and detection of spa gene. The percentages of true and false identities were determined. Results: Of the 507 isolates previously identified as S. aureus, only 54 (11 %) were confirmed as S. aureus while the rest were coagulase negative Staphylococci (85 % misidentification rate), Bacillus sp. (12 % misidentification rate), and Brevibacterium sp. (3 % misidentification rate). Conclusion: A high rate of false positive identification of S. aureus which could lead to the misuse of antibiotics in emergency situation has been identified in this study. The use of standard methods for the identification of S. aureus at all times is highly recommended.

An integrated approach for assessing the bioreceptivity of glazed tiles to phototrophic microorganisms

A laboratory-based methodology was designed to assess the bioreceptivity of glazed tiles. The experimental set-up consisted of multiple steps: manufacturing of pristine and artificially aged glazed tiles, enrichment of phototrophic microorganisms, inoculation of phototrophs on glazed tiles, incubation under optimal conditions and quantification of biomass. In addition, tile intrinsic properties were assessed to determine which material properties contributed to tile bioreceptivity. Biofilm growth and biomass were appraised by digital image analysis, colorimetry and chlorophyll a analysis. SEM, micro-Raman and micro-particle induced X-ray emission analyses were carried out to investigate the biodeteriorating potential of phototrophic microorganisms on the glazed tiles. This practical and multidisciplinary approach showed that the accelerated colonization conditions allowed different types of tile bioreceptivity to be distinguished and to be related to precise characteristics of the material. Aged tiles showed higher bioreceptivity than pristine tiles due to their higher capillarity and permeability. Moreover, biophysical deterioration caused by chasmoendolithic growth was observed on colonized tile surfaces.

Rock paintings and microorganisms: a new insight on Escoural cave

European cave art is of tremendous importance to understand the cultural traditions of the Upper Palaeolithic (35 000 – 10 000 BP) populations. Indeed, Prehistoric communities performed numerous cave paintings all over Western Europe. Understanding these artworks should provide a better knowledge of these early cultural aspects. Although numerous studies have been carried out to analyse the materials used by those communities, nothing has been done on the techniques’ palette of Escoural Cave’s representations. The present work aims at providing the very first data about the techniques and materials used by the Prehistoric to perform the cave paintings of Escoural (Alentejo, Portugal), and the microorganisms possibly endangering this unique parietal art. In situ observations coupled with an extensive micro-sampling and micro-destructive analyses allowed to characterize the coloured material and the way they were applied on the walls of the cave. Both red and black pigments present major composition’s disparities among the different paintings and drawings, supporting a more complex occupations’ chronology than what was earlier thought. The Palaeolithic paintings have suffered deterioration from environmental conditions and include chemical, mechanical and aesthetic alterations, possibly as a result of fungal activity. The standard techniques for biological assessments used in these contexts provided important insights on the diversity of the microbial population, though they have accuracy limitations. To understand the extent and viability of the existing microbiota, DNA quantification and biomarkers analyses, such as desidrogenase activity were performed and correlated with ergosterol amounts; RESUMO: A Arte Rupestre Europeia é de grande importância para compreender as tradições culturais da população do Paleolítico Superior (35 000 - 10 000 BP). De fato, as comunidades Pré-históricas realizaram inúmeras pinturas rupestres em toda a Europa Ocidental, sendo crucial compreender estas obras de forma a proporcionar um melhor conhecimento destes ancestrais aspectos culturais. Embora vários estudos tenham sido realizados para analisar os materiais utilizados por estas comunidades, nada foi efetuado sobre a técnica de execução das representações presentes na Gruta do Escoural. O presente trabalho visa fornecer os primeiros dados sobre as técnicas e materiais utilizados na Pré-História para executar as pinturas rupestres de Escoural (Alentejo, Portugal) bem como caracterização dos microorganismos possivelmente associados aos danos deste bem único. Observações in situ, juntamente com uma extensa micro-amostragem e análises micro-destrutivas permitiu caracterizar os pigmentos utilizados e a forma como eles foram aplicados nas paredes da caverna. Tanto os pigmentos vermelhos como os pretos apresentam composição distinta nas diversas pinturas e desenhos aí representados, apoiando a presença de diferentes ocupações contrariamente ao que se pensava até então. As pinturas Paleolíticas têm sofrido deterioração, devido às condições ambientais, nomeadamente alterações químicas, mecânicas e, possivelmente como resultado da atividade fúngica. As técnicas usualmente utilizadas para a avaliação de contaminação biológica fornecem informação importante sobre a diversidade da população microbiana, embora apresentem algumas limitações. Para entender a extensão e a viabilidade da microbiota existente, a quantificação de DNA e análise de biomarcadores como actividade de desidrogenases foram realizadas e correlacionadas com o conteúdo em ergosterol.

Inimigos naturais da parte aérea da cultura de milho tratada com EM (Eficient Microorganisms), na região de Guaíra-SP.

As pragas da parte aérea da cultura de milho na regiao de Guaira-SP sao atacadas pelos inimigos naturais Doru luteipes Cycloneda sanguinea, Chrysoperla externa, Callida sp., Zelus sp., Geocoris sp., varias especies de aranhas e parasitoides. Este trabalho teve como objetivo avaliar o efeito do EM (efficient microorganisms) sobre a fauna benéfica dessa cultura. Foram avaliados 5 campos sendo 3 deles conduzidos pelo sistema de plantio convencional e 2 deles sob sistema de plantio direto. Cada campo foi divido em 4 faixas (parcelas), sendo 2 delas tratadas com EM e duas sem aplicação do produto, que serviram de testemunhas. No campo 1 foram feitas 3 avaliações, nos estágios de 4-6 folhas, 8-10 folhas de espigamento, tendo sido constatado no tratamento PCEM (plantio convencional com EM), 7,56%, 43,99% e 32,83% de inimigos naturais; no tratamento PC (testemunha) foram encontrados 14,22%, 52,07% e 28,19%, respectivamente. No campo 2 foram feitas 2 avaliações nos estágios de 12-14 folhas e no de espigamento, tendo sido obtidos no tratamento PCEM, 21,90% e 31,79%; em PC, 19,53% e 25,53%. No campo 3 foram feitas 2 avaliações, ambas no estagio de espigamento, tendo sido encontrados em PCEM 18,81% e 13,78; em PC, 26,28% e 16,71%. No campo 4 , sob plantio direto, foram feitas 3 avaliações nos estágios de 6-8 folhas, e 2 avaliações no estagio espigamento, tendo sido obtidos em PDEM 13,71%,31,44% e 18,00%; em PD, 11,41%, 28,15% e 18,74%. No campo 5 teve 2 avaliações, nos estágios de 8-10 folhas e no de espigamento, obtendo-se em PDEM 17,22% e 30,96%; em PD, 20,24% e 30,38. A medida que a cultura envelhece, em ambos os sistemas de condução da cultura as parcelas tratadas com EM tendem a apresentar maior proporção de inimigos naturais.

Inimigos naturais da parte aérea da cultura de feijão tratada co EM (Efficient Microorganisms), na região de Guaíra.

Os inimigos naturais de pragas da cultura de feijão constituídas por aranhas, Chrysoperla externa, Cycloneda sanguínea, Zelus sp., Geocoris sp. e Nabis sp. são importantes controladores de pragas dessa cultura. Este trabalho teve como objetivo testar o efeito de EM (efficient microorganisms) sobre a fauna de organismos benéficos. Foram avaliados 5 campos, sendo três deles conduzidos pelo sistema de plantio convencional (campos 1,2 e 3) e dois deles pelo sistema de plantio direto (campos 4 e 5). No campo 1 foram feitas 3 avaliações com a cultura nos estágios V4, R6 e R7, tendo sido encontrados nas parcelas tratadas com EM (PCEM), 19,735, 17,89%, 7,87% de inimigos naturais, enquanto nas parcelas testemunhas sem aplicação de EM (PC), 25,70%, 15,94% e 13,54%. No campo 2 foram feitas 2 avaliações nos estágios R6 e R7, tendo sido encontrados nas parcelas PCEM 20,20% e 15,84%; nas parcelas PC esses percentuais foram de 18,83, e 13,66. No campo 3 foram feitas 2 avaliações nos estagios R7 e R9, obtendo-se em PCEM, 18,16% e 20,37%, enquanto em PC, 22,59% e 14,90% de inimigos naturais. No campo 4 foi feita uma única avaliação no estagio R7 e os resultados foram de 21,47% (PDEM) e 22,89% (PD). No campo 5 foram feitas duas avaliações nos estágios R6 e R7, obtendo-se em PDEM 22,05% e 18,89%; no tratamento PD, 28,80 e 24,54%. Estes resultados se referem ao primeiro ano de aplicacao de EM, devendo ser repetidas nos anos seguintes, nos quais se espera maior percentual de inimigos naturais nas parcelas tratadas com EM que na parcelas testemunhas, o que já esta ocorrendo nos campos 2 e 3.

Microbial Evaluation Of Traumatized Teeth Treated With Triple Antibiotic Paste Or Calcium Hydroxide With 2% Chlorhexidine Gel In Pulp Revascularization.

Revascularization outcome depends on microbial elimination because apical repair will not happen in the presence of infected tissues. This study evaluated the microbial composition of traumatized immature teeth and assessed their reduction during different stages of the revascularization procedures performed with 2 intracanal medicaments. Fifteen patients (7-17 years old) with immature teeth were submitted to the revascularization procedures; they were divided into 2 groups according to the intracanal medicament used: TAP group (n = 7), medicated with a triple antibiotic paste, and CHP group (n = 8), dressed with calcium hydroxide + 2% chlorhexidine gel. Samples were taken before any treatment (S1), after irrigation with 6% NaOCl (S2), after irrigation with 2% chlorhexidine (S3), after intracanal dressing (S4), and after 17% EDTA irrigation (S5). Cultivable bacteria recovered from the 5 stages were counted and identified by means of polymerase chain reaction assay (16S rRNA). Both groups had colony-forming unit counts significantly reduced after S2 (P < .05); however, no significant difference was found between the irrigants (S2 and S3, P = .99). No difference in bacteria counts was found between the intracanal medicaments used (P = .95). The most prevalent bacteria detected were Actinomyces naeslundii (66.67%), followed by Porphyromonas endodontalis, Parvimonas micra, and Fusobacterium nucleatum, which were detected in 33.34% of the root canals. An average of 2.13 species per canal was found, and no statistical correlation was observed between bacterial species and clinical/radiographic features. The microbial profile of infected immature teeth is similar to that of primarily infected permanent teeth. The greatest bacterial reduction was promoted by the irrigation solutions. The revascularization protocols that used the tested intracanal medicaments were efficient in reducing viable bacteria in necrotic immature teeth.

Inhibitory Effects Of A Cured Antibacterial Bonding System On Viability And Metabolic Activity Of Oral Bacteria.

To evaluate the antimicrobial efficacy of Clearfil SE Protect (CP) and Clearfil SE Bond (CB) after curing and rinsed against five individual oral microorganisms as well as a mixture of bacterial culture prepared from the selected test organisms. Bacterial suspensions were prepared from single species of Streptococcus mutans, Streptococcus sobrinus, Streptococcus gordonii, Actinomyces viscosus and Lactobacillus lactis, as well as mixed bacterial suspensions from these organisms. Dentin bonding system discs (6 mm×2 mm) were prepared, cured, washed and placed on the bacterial suspension of single species or multispecies bacteria for 15, 30 and 60 min. MTT, Live/Dead bacterial viability (antibacterial effect), and XTT (metabolic activity) assays were used to test the two dentin system's antibacterial effect. All assays were done in triplicates and each experiment repeated at least three times. Data were submitted to ANOVA and Scheffe's f-test (5%). Greater than 40% bacteria killing was seen within 15 min, and the killing progressed with increasing time of incubation with CP discs. However, a longer (60 min) period of incubation was required by CP to achieve similar antimicrobial effect against mixed bacterial suspension. CB had no significant effect on the viability or metabolic activity of the test microorganisms when compared to the control bacterial culture. CP was significantly effective in reducing the viability and metabolic activity of the test organisms. The results demonstrated the antimicrobial efficacy of CP both on single and multispecies bacterial culture. CP may be beneficial in reducing bacterial infections in cavity preparations in clinical dentistry.

Lawsonia Inermis-mediated Synthesis Of Silver Nanoparticles: Activity Against Human Pathogenic Fungi And Bacteria With Special Reference To Formulation Of An Antimicrobial Nanogel.

Lawsonia inermis mediated synthesis of silver nanoparticles (Ag-NPs) and its efficacy against Candida albicans, Microsporum canis, Propioniabacterium acne and Trichophyton mentagrophytes is reported. A two-step mechanism has been proposed for bioreduction and formation of an intermediate complex leading to the synthesis of capped nanoparticles was developed. In addition, antimicrobial gel for M. canis and T. mentagrophytes was also formulated. Ag-NPs were synthesized by challenging the leaft extract of L. inermis with 1 mM AgNO₃. The Ag-NPs were characterized by Ultraviolet-Visible (UV-Vis) spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), nanoparticle tracking and analysis sytem (NTA) and zeta potential was measured to detect the size of Ag-NPs. The antimicrobial activity of Ag-NPs was evaluated by disc diffusion method against the test organisms. Thus these Ag-NPs may prove as a better candidate drug due to their biogenic nature. Moreover, Ag-NPs may be an answer to the drug-resistant microorganisms.

Clustering Of Water Bodies In Unpolluted And Polluted Environments Based On Escherichia Coli Phylogroup Abundance Using A Simple Interaction Database.

Different types of water bodies, including lakes, streams, and coastal marine waters, are often susceptible to fecal contamination from a range of point and nonpoint sources, and have been evaluated using fecal indicator microorganisms. The most commonly used fecal indicator is Escherichia coli, but traditional cultivation methods do not allow discrimination of the source of pollution. The use of triplex PCR offers an approach that is fast and inexpensive, and here enabled the identification of phylogroups. The phylogenetic distribution of E. coli subgroups isolated from water samples revealed higher frequencies of subgroups A1 and B23 in rivers impacted by human pollution sources, while subgroups D1 and D2 were associated with pristine sites, and subgroup B1 with domesticated animal sources, suggesting their use as a first screening for pollution source identification. A simple classification is also proposed based on phylogenetic subgroup distribution using the w-clique metric, enabling differentiation of polluted and unpolluted sites.