Application of XeCl308nm excimer laser radiation to mutate industrial microorganisms

EnIn this study, we have investigated the effects of an XeCl308 nm excimer laser radiation on bacterial mutagenesis. Our experiments have revealed that the mutagenesis inducted by the XeCl308 nm excimer laser radiation is independent from RecA protein, the regulator of the SOS response, unlike UV254 nm radiation that is not mutagenic for Escherichia coli mutants lacking the RecA protein. This found suggests that the UV308 nm laser radiation might be mutagenic also in microorganisms naturally lacking the SOS response. To test this hypothesis, we applied our innovative mutagenesis approach on Nonomuraea ATCC 39727, an industrial strain producing an antibiotic, which is relatively refractory to UV254 nm radiation-induced mutagenesis. Our results demonstrated the efficiency of XeCl308 nm excimer laser radiation to induce mutagenesis in Nonomuraea ATCC 39727

DNA damage by a single intense shot of soft X-rays emitted by a laser-produced plasma

EnA suitable plane transmission line was developed and its behaviour analysed at 900 MHz radiofrequency fields to study the DNA mutability and repair of microorganisms. In this work, utilizing such a device, we investigated the behaviour of the DNA mutability and repair of Escherichia coli strains. The transmission line was very simple and versatile in changing its characteristic resistance and field intensity by varying its sizes. In absence of cell samples inside the transmission line, the relative modulation of the electric and/or magnetic field was ±31% with respect to the mean values, allowing the processing of more samples at different exposure fields in a single run. Slight decrease in spontaneous mutability to rifampicin-resistance of the E. Coli JC411 strain, was demonstrated in mismatch-repair proficient samples exposed to the radio-frequency fields during their growth on solid medium

Sorgenti laser per biomateriali

In questo lavoro vengono messe a confronto due diverse tecniche per migliorare le proprietà delle superfici di materiali biomedici; l‟irraggiamento laser e l‟impiantazione ionica. L‟irraggiamento laser è eseguito mediante una sorgente ad eccimeri KrF e l‟impiantazione ionica mediante l‟acceleratore Platone che utilizza la tecnica LIS (Laser Ion Source). Mi-sure di angolo di contatto e rugosità sono state eseguite sui campioni prima e dopo ogni trattamento in modo da avere informazioni sulle modifiche. L‟impiantazione ionica è stata eseguita anche su target di acciaio AISI 420, lega utilizzata per realizzare strumenti medicali. Si è visto che l‟utilizzo di fasci di ioni di Ag aumenta l‟antibattericità degli strumenti

Oral complications of Type 1 diabetes mellitus in a non-smoking population

Type 1 diabetes mellitus (T1DM) is a complex metabolic condition that results in hyperglycemia due to insulin deficiency (Daneman, 2006). Diabetes has a range of effects on almost every system in the body including the kidneys, the eyes, the cardiovascular system, the genito-urinary system, the gastro-intestinal system and the nervous system (Daneman, 2006). The effects of this ondition are widespread and have a significant impact both on life expectancy and the quality of life of individuals suffering from diabetes (Scottish Diabetes Survey Monitoring Group, 2011). The impact of diabetes on oral health has been investigated over many decades, however, the conclusions have been varied and study design has not always been adequate (Mealey et al., 2006; Khader et al., 2006; Chávarray et al., 2009). Research presented in this thesis is largely the result of a cross-sectional clinical study examining the oral cavities of non-smoking T1DM patients, funded by the Chief Scientist Office of the Scottish Government. The clinical part of the study took place between January 2006 and May 2009 in Glasgow Dental Hospital. Chapter one provides an introduction and narrative review on the subject of T1DM, periodontal disease, and the various other reported oral manifestations of diabetes mellitus. The methods for measuring general and oral health related quality of life outcomes are also discussed. Chapter one reveals some of the inadequacies of studies nvestigating the link between T1DM and oral disease to date and ontextualises the studies presented in this thesis. Chapter two presents the main periodontal findings of a large cross-sectional study. 112 non-diabetic subjects and 203 subjects with type 1 diabetes were examined. 203 diabetic patients were divided into well controlled and poorly controlled groups based on their average blood sugar levels over the previous two years. 169 were poorly controlled. (PCD). Those with T1DM, (especially those with poor glycaemic control) had a greater extent and severity of periodontitis than those without diabetes. There was also some evidence that never smoking T1DM patients were more likely to have periodontal disease than non-diabetic subjects. The odds ratio (OR) was 1.43 [0.74 to 2.75] (p = 0.29) for all T1DM patients and 1.58 [0.75 to 3.33] (p = 0.23) for PCD. This difference remained even after the multivariable analysis took into account age, gender and lifestyle including: body mass index of the subject; whether they had smoked in the past; whether they attended a dentist; their level of education and how deprived the area they lived in was. Chapter three presents an analysis of the impact of age, HbA1c, and duration on the expression of periodontal disease in T1DM subjects. Cross-tabulations and multivariable logistic regression analysis was performed on the periodontal data from T1DM subjects and non-diabetic subjects in order to determine the relationship between age, HbA1c and duration, and periodontitis. Diabetic subjects developed periodontitis at a younger age than non-diabetes subjects. This will represent a significant impact on life time dental service provision for subjects affected at a young age. The relationship between HbA1c and severe periodontitis is not a simple one. It is possible that unknown factors confound the relationship between glycaemic control and periodontitis. There was no relationship between duration of diabetes and periodontitis when age was controlled for. Chapter four presents the results of a small study investigating biomarkers of bone turnover in patients with and without T1DM and in patients with and without periodontitis. Patients with T1DM had higher levels of osteoprotegerin an osteoprotective molecule that normally leads to a reduced propensity for bone loss. T1DM patients were also shown to have reduced levels of biomarkers of bone formation (osteocalcin). It is possible that a reduced capacity for bone repair and regeneration may account for the increase levels of periodontitis seen in T1DM. Further prospective studies would be required to confirm this hypothesis. Chapter five investigated the level of caries and oral mucosal abnormalities in T1DM. There was little difference in caries indicators or in oral mucosal lesions between the groups. There was no difference in the bacterial microflora and in the level of resistance to antibiotics found in this cohort. T1DM patients, however, did have an increase in the symptoms of dry mouth, an increased density of candida colonisation and reduced salivary flow rates.Chapter six reports the data derived from the oral health questionnaire, including the Oral Health Impact Profile -14 (OHIP-14) and the Audit of Diabetes Dependent Quality of Life (ADDQOL©). Patients with T1DM, despite having increased levels of periodontal disease, reduced salivary flow rates and increased symptoms of xerostomia did not have higher OHIP scores by any measure. The reasons for this apparently negligible impact of oral disease or oral health related quality of life are discussed. The OHIP-14 was shown to have construct validity in this population although the correlations were relatively weak and the differences were small. It is possible that patients with T1DM do not consider the impact of their oral health to be a significant problem in light of their other on-going medical issues. This finding requires further in-depth investigation of the psychology behind this apparent reduced impact. This is the first study of its kind to examine the oral and dental health of non-smoking type 1 diabetic patients. The conclusions from the clinical data support the view that patients with T1DM should be targeted with oral and dental health advice. Encouragingly the prevalence of periodontitis was lower in well controlled diabetic subjects suggesting that the effect of T1DM on the oral cavity can be ameliorated by good glycaemic control even though logistic regression analysis did not show a linear relationship. It is important that health rofessionals work together in order to prevent and manage the oral complications of T1DM in the same way that there are preventive and screening programmes for other diabetic complications. The pathogenesis behind the increased prevalence and severity of periodontal disease in T1DM requires further study.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Caratterizzazione di Batteri Vibrio harveyi irradiati con luce UV e raggi X

Lo studio dei batteri sottoposti a stimolazioni dovute all'ambiente è di estremo interesse per impli-cazioni strutturali, meccanicistiche ed evolutive. Bat-teri luminescenti evoluti in determinati ambienti han-no sviluppato particolari risposte e il loro comporta-mento può fornire informazioni sulla funzione e sulla produzione dell‟enzima luciferina. Per esaminare l'in-terazione con radiazione UV, in condizioni controlla-te di laboratorio sono stati utilizzati ceppi batterici foto-luminescenti appartenenti alla specie Vibrio har-veyi campionati da una grotta costiera con elevato contenuto di radon che genera radiazioni ionizzanti. La sopravvivenza dei ceppi batterici è stata analizza-ta, alla luce e al buio, a seguito di una varietà di trat-tamenti genotossici tra cui esposizione alle radiazioni UV. I ceppi sono stati irradiati mediante una lampada germicida. I risultati hanno dimostrato che la maggior parte dei ceppi esibiscono un basso tasso di sopravvi-venza dopo l'esposizione ai raggi UV. Tutti i ceppi dopo esposizione a luce visibile e ai raggi UV hanno mostrato una forte capacità di fotoriattivazione. Que-sta capacità era inaspettata, poiché questi batteri sono stati prelevati da un ambiente buio in assenza raggi UV. Questo porta ad ipotizzare che la fotoriattivazio-ne in questi batteri potrebbe essere stata sviluppata dagli stessi per riparare le lesioni del DNA provocate anche da radiazioni diverse dall‟UV (ad esempio, raggi X) e che i batteri luminescenti potrebbero usare la luce da essi emessa per effettuare la fotoriattivazio-ne. L'elevata capacità di fotoriattivazione dei batteri è stata anche confermata dai risultati di deconvoluzio-ne. La deconvoluzione è stata applicata agli spettri di emissione che ha evidenziato la presenza di diversi picchi. La presenza del picco nel visibile è in grado di controllare l'enzima fotoliasi

Microbes at work in perfumery: odorous compounds from free-living and symbiotic bacteria living on plants and humans

Bacteria synthesise an extremely rich repertoire of odorous compounds. Unfortunately this feature is not much known and bacteria are more often associated with the bad smell of rotting material. The focus of this review is on the capability of bacteria to synthesize odorous volatiles, either when they are free-living in soil and aquatic environments or when they establish symbiotic association with plants and animals, with specific reference to humans. In particular, the biological and ecological significance of bacterial volatiles and their biotechnological perspectives are covered in this present work

Enhancing UHMWPE Antibacterial Properties Through Ion Implantation

We propose a new technique for the surface modification of biomedical polymers in order to strongly enhance its antimicrobial quality via ion implantation, in alternative to the well known ones that use chemical reactions or films deposition. We present the experimental results of implantation of ultra high molecular weight polyethylene (UHMWPE) samples by Ag, Cu and Ti ions. As accelerator we used “Platone”, a homemade laser ion source accelerator device. The ions were extracted from the plasma generated by a KrF excimer laser operating at 248 nm. A laser beam of 12 mJ/pulse was focused on a solid target mounted in a vacuum chamber in order to obtain plasma. The laser spot was estimated to be of 0.005 cm2. This device has an accelerating system composed by two different stages. Using pure Ag, Cu and Ti disks as laser targets and applying voltages of 40 kV to the first accelerating stage and 20 kV to the second one, we produced ion beams containing about 1011 ions/cm2 per pulse. The penetration depth of ions was estimated by the Srim code and the largest depth was achieved with Ti ions. Operating 22000 laser shots we implanted our samples with doses of about 1015 ions/cm2. Next we analyzed the effects of ion implantation on the bacterial adherence to UHMWPE samples. To test their antimicrobial quality, a Staphylococcus aureus strain isolated from a catheter-related bloodstream infection was used in these assays. The results demonstrate that the adherence of bacteria is reduced of 21%, 7% and 90% for Ag, Cu and Ti ions-implanted samples with respect to the control ones, confirming the effectiveness of our approach

Radiofrequency transmission line for bioluminescent Vibrio sp. irradiation

We present the study and the analyses of a transmission line for radiofrequency (RF) irradiation of bacteria belonging to Vibrio harveyi-related strain PS1, a bioluminescent bacterium living in symbiosis with many marine organisms. The bioluminescence represents a new biologic indicator which is useful for studying the behaviour of living samples in the presence of RF waves due to the modern communication systems. A suitable transmission line, used as an irradiating cell and tested up to the maximum frequency used by the global system for mobile communications and universal mobile telecommunications system transmissions, was characterized. In this experiment, the RF voltage applied to the transmission line was 1V. Due to short dimensions of the line and the applied high frequencies, standing waves were produced in addition to progressing waves and the electric field strength varies particularly along the longitudinal direction. The magnetic field map was not strongly linked to the electric one due to the presence of standing waves and of the outgoing irradiation. RF fields were measured by two homemade suitable probes able to diagnostic fields of high frequency. The field measurements were performed without any specimens inside the line. Being our sample made of living matter, the real field was modified and its value was estimated by a simulation code. The bioluminescence experiments were performed only at 900MHz for two different measured electric fields, 53 and 140V/m. The light emission was measured right from the beginning and after 7 and 25 h. Under RF irradiation, we found that the bioluminescence activity decreased. Compared with the control sample, the diminution was 6.8% and 44% after 7 and 25 h of irradiation, respectively, both with the low or high field. No changes of the survival factor for all the samples were observed. Besides, to understand the emission processes, we operated the deconvolution of the spectra by two Gaussian curves. The Gaussian peaks were approximately centered at 460 nm and 490 nm. The 490 nm peak was higher than the control one. Under RF, the 490 nm peak decreased compared to the 460 nm one. The decreasing was stronger for the sample in the higher field. The ratio of the emission area of the 490 nm to 460 nm was 5 for the control sample. It decreased up to 1.6 for the samples under RF. The bioluminescence improves the DNA repair by photoreactivation, and there is evidence that photolyase is preferentially activated by blue/violet light. Our finding suggests that RF exposure may stimulate DNA repair by shifting the emission spectra from blue/green (490 nm) to blue/violet (460 nm). VC 2012 American Institute of Physics

Un approccio computazionale per lo studio di nodi metabolici coinvolti con la sintesi di spiramicina I in Streptomyces ambofaciens

Gli streptomiceti rappresentano il genere di organismi maggiormente utilizzati per la produzione industriale di metaboliti secondari. In particolare S. ambofaciens è il ceppo produttore della spiramicina (antibiotico). Una delle sfide scientifiche più importanti in questo campo è la capacità di modulare il metabolismo veicolando il flusso di carbonio verso la sintesi della molecola di interesse. In questo studio, utilizzando metodi computazionali, è stata indagata la funzione di una proteina sconosciuta (pirina) che regola la tappa iniziale della sintesi della spiramicina. In particolare uno dei target della pirina è una deidrogenasi che è correlata con la β-ossidazione e che controlla in maniera indiretta la formazione di etilmalonil-CoA importante precursore dell'antibiotico in questione

Pseudomonas aeruginosa orchestrates twitching motility by sequential control of type IV pili movements

Prokaryotes have the ability to walk on surfaces using type IV pili (TFP), a motility mechanism known as twitching1,2. Molecular motors drive TFP extension and retraction, but whether and how these movements are coordinated is unknown3. Here, we reveal how the pathogen Pseudomonas aeruginosa coordinates the motorized activity of TFP to power efficient surface motility. To do this, we dynamically visualized TFP extension, attachment and retraction events at high resolution in four dimensions using label-free interferometric scattering microscopy (iSCAT)4. By measuring TFP dynamics, we found that the retraction motor PilT was sufficient to generate tension and power motility in free solution, while its partner ATPase PilU may improve retraction only in high-friction environments. Using precise timing of successive attachment and retraction, we show that P. aeruginosa engages PilT motors very rapidly and almost only when TFP encounter the surface, suggesting contact sensing. Finally, measurements of TFP dwell times on surfaces show that tension reinforced the adhesion strength to the surface of individual pili, thereby increasing effective pulling time during retraction. The successive control of TFP extension, attachment, retraction and detachment suggests that sequential control of motility machinery is a conserved strategy for optimized locomotion across domains of life. </p