Talk2clean: application of probiotics to control biofilm in industrial water circuits – a innovative application

2020 ◽  
Author(s):  
Hetty KleinJan ◽  
Christophe Meunier ◽  
Stéphane Nonet ◽  
Mickael Michel
Keyword(s):  
Synthetic Medium ◽  
Cooling Water ◽  
Protective Layer ◽  
Quorum Quenching ◽  
Pilot Scale ◽  
Signalling Molecules ◽  
Biofilm Removal ◽  
Plate Counts ◽  
Heterotrophic Plate Counts ◽  
User Friendly

<p>Biofilms are omnipresent in industrial cooling water circuits and frequently lead to technical and economic problems. Yet, methods to remove biofilms may be inefficient, due to the EPS layer, which provides a protective layer against penetration of disinfectants. In combination with stricter legislation and increased environmental awareness, this has opened the search for alternative strategies to control biofilms in cooling water systems.</p> <p>In this study we implement a novel biofilm removal strategy, in which we target the intercellular language involved in the formation of biofilm structures. This language consists of signalling molecules (autoinducers) excreted by biofilm forming bacteria, a process referred to as quorum sensing (QS). We aim to alter QS via the activation of an antagonistic process called quorum quenching (QQ). Quorum quenching is a process that naturally occurs in bacterial communities; hence the final product is environment, - and user-friendly and thus a valuable alternative to the oxidising chemical products that are often used to clean cooling water circuits.</p> <p>Here we present the first application of a QQ-product tested on pilot scale using parameters that resemble industrial evaporative cooling towers. This setting is particularly interesting as it an open system, fed with various types of make-up water, and comprised of biofilms adjusted to high operating temperatures.</p> <p>The QQ product was tested using a closed, tube-like system, under continuous flow, fed with a propionic, - and acetic acid rich synthetic medium. Hydraulic retention time (HRT) was gradually shifted over a time span of 6 weeks. Heterotrophic plate counts were acquired once per week from the planktonic and biofilm phase. A pilot without the addition of QQ was ran in parallel as a control.</p> <p>Our results show that the QQ product reduced and delayed the formation of biofilm compared to the control. Interestingly, this difference diminished when the HRT was modified. Metagenomic analysis of the biofilm phase, revealed that 16S rRNA sequences corresponding to the QQ were also strongly reduced during this shift, indicating a wash-out of the QQ product. The exact interaction of HRT and presence of QQ will be analysed in more depth using QQ specific qPCR primers.</p>

scholarly journals A single point mutation converts a glutaryl-7-aminocephalosporanic acid acylase into an N-acyl-homoserine lactone acylase

2021 ◽  
Author(s):  
Shereen A. Murugayah ◽  
Gary B. Evans ◽  
Joel D. A. Tyndall ◽  
Monica L. Gerth
Keyword(s):  
Single Point ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Site Directed Mutagenesis ◽  
Saturation Mutagenesis ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Acyl Homoserine Lactone ◽  
Signalling Molecules ◽  
Single Amino Acid Residue

Abstract Objective To change the specificity of a glutaryl-7-aminocephalosporanic acid acylase (GCA) towards N-acyl homoserine lactones (AHLs; quorum sensing signalling molecules) by site-directed mutagenesis. Results Seven residues were identified by analysis of existing crystal structures as potential determinants of substrate specificity. Site-saturation mutagenesis libraries were created for each of the seven selected positions. High-throughput activity screening of each library identified two variants—Arg255Ala, Arg255Gly—with new activities towards N-acyl homoserine lactone substrates. Structural modelling of the Arg255Gly mutation suggests that the smaller side-chain of glycine (as compared to arginine in the wild-type enzyme) avoids a key clash with the acyl group of the N-acyl homoserine lactone substrate. Conclusions Mutation of a single amino acid residue successfully converted a GCA (with no detectable activity against AHLs) into an AHL acylase. This approach may be useful for further engineering of ‘quorum quenching’ enzymes.

scholarly journals Endotoxin contamination in the dental surgery

2007 ◽  
Vol 56 (9) ◽  
pp. 1230-1234 ◽  
Author(s):  
M. K. Huntington ◽  
J. F. Williams ◽  
C. D. Mackenzie
Keyword(s):  
Bacterial Load ◽  
Dental Surgery ◽  
Paired Samples ◽  
Dental Procedures ◽  
Large Numbers ◽  
Endotoxin Exposure ◽  
Endotoxin Contamination ◽  
Plate Counts ◽  
High Concentrations ◽  
Heterotrophic Plate Counts

Dental waterlines contain large numbers of Gram-negative bacteria. Endotoxin, a component of such organisms, has significant health implications. Paired samples of dental unit water and the aerosols generated during dental procedures were collected, and assayed for bacteria and endotoxin levels, using heterotrophic plate counts and the Limulus amoebocyte lysate test. Consistent with published studies, the extent of bacterial contamination in the dental waters sampled for this investigation surpassed the levels associated with potable water, with counts in excess of 2.0×106 c.f.u. ml−1 in some samples. Correspondingly high concentrations of endotoxin [up to 15 000 endotoxin units (EU) ml−1] were present in the water. A statistically significant Spearman correlation coefficient of ρ=0.94 between endotoxin (EU ml−1) and bacterial load (c.f.u. ml−1) was demonstrated. All of the aerosol samples contained detectable endotoxin. Further studies of the consequences of dental endotoxin exposure, and evaluation of means to prevent exposure, are warranted.

Parameters predictive of Legionella contamination in hot water systems: Association with trace elements and heterotrophic plate counts

2011 ◽  
Vol 45 (6) ◽  
pp. 2315-2321 ◽  
Author(s):  
Annalisa Bargellini ◽  
Isabella Marchesi ◽  
Elena Righi ◽  
Angela Ferrari ◽  
Stefano Cencetti ◽  
...  
Keyword(s):  
Trace Elements ◽  
Water Systems ◽  
Hot Water ◽  
Plate Counts ◽  
Heterotrophic Plate Counts

scholarly journals Taking Screenshots of the Invisible: A Study on Bacterial Contamination of Mobile Phones from University Students of Healthcare Professions in Rome, Italy

2020 ◽  
Vol 8 (7) ◽  
pp. 1075 ◽  
Author(s):  
Domenico Cicciarella Modica ◽  
Massimo Maurici ◽  
Gian Loreto D’Alò ◽  
Cinzia Mozzetti ◽  
Alessandra Messina ◽  
...  
Keyword(s):  
Mobile Phones ◽  
Staphylococcus Epidermidis ◽  
Univariate Analysis ◽  
Clinical Settings ◽  
Linear Regression Models ◽  
Biochemical Tests ◽  
E Coli ◽  
Plate Counts ◽  
Healthcare Professions ◽  
Heterotrophic Plate Counts

Mobile phones (MPs) are commonly used both in the personal and professional life. We assessed microbiological contamination of MPs from 108 students in healthcare professions (HPs), in relation to their demographic characteristics and MPs handling habits, collected by means of a questionnaire. Cultural and biochemical tests were performed, and statistical analyses were carried out. Staphylococci were present in 85% of MPs, Enterococci in 37%, Coliforms in 6.5%; E. coli was never detected. Staphylococcus epidermidis was the most frequently isolated staphylococcal species (72% of MPs), followed by S. capitis (14%), S. saprophyticus, S. warneri, S. xylosus (6%), and by S. aureus (4%). Heterotrophic Plate Counts (HPC) at 37 °C, ranged from 0 to 1.2 × 104 CFU/dm2 (mean = 362 CFU/dm2). In univariate analysis, the male gender only was significantly associated with higher HPCs and enterococcal contamination. Multiple linear regression models explained only 17% and 16% of the HPC 37 °C and staphylococcal load variability, respectively. Developing specific guidelines for a hygienic use of MPs in clinical settings, for preventing cross-infection risks, is advisable, as well as introducing specific training programs to HP students. MPs decontamination procedures could also be implemented in the community.

Coliforms and other microbial indicators occurrence in water and biofilm in full-scale distribution systems

2006 ◽  
Vol 54 (3) ◽  
pp. 41-48 ◽  
Author(s):  
M. Batté ◽  
C. Féliers ◽  
P. Servais ◽  
V. Gauthier ◽  
J.-C. Joret ◽  
...  
Keyword(s):  
Water Quality ◽  
Residence Time ◽  
Distribution Systems ◽  
Full Scale ◽  
Bacterial Indicators ◽  
Total Coliforms ◽  
E Coli ◽  
Plate Counts ◽  
Microbiological Water Quality ◽  
Heterotrophic Plate Counts

Biofilm and microbial water quality were studied in four middle size full-scale distribution systems (DS) in France serving 5,000–30,000 inhabitants (maximum residence time 23–160 h) through three sampling campaigns over 1 year. Three of these DSs were chosen because of a quite high occurrence of bacterial indicators (i.e. total coliforms), the last DS was considered as a reference. Biofilm was studied on cast iron coupons incubated for more than 1 month in devices continuously fed with water from the DS in conditions imitating those met in DS. The devices were located at different points (4–6) along each DS. The abundance of bacteria in biofilm was estimated by heterotrophic plate counts (HPC) after detachment of the biofilm from the support by sonication. Microbiological water quality was estimated in parallel; analysis of total coliforms, E. coli, enterococci and anaerobic sulphide-reducing bacteria spores (ASRB spores) was carried out in biofilm and water. Over the period of the study, 171 water samples and 57 biofilm samples were collected. Over these 171 waters, 19 (11%) were positive for at least one of the measured indicators while two biofilm samples were positive (3.5%). Significant differences were observed in the levels of contamination between the DSs. High residence time in the DS, low disinfectant residual and high temperature increased the risk of indicator occurrence in the water phase. Due to the low number of biofilm samples positive for bacterial indicators, the data collected in the present study did not allow observation of a direct association between biofilm and water contaminations, even if the occurrence of indicators in water appeared on DSs with the highest density of biofilm (HPC).

scholarly journals Effects of Hydrogen Peroxide on Dental Unit Biofilms and Treatment Water Contamination

2011 ◽  
Vol 05 (01) ◽  
pp. 047-059 ◽  
Author(s):  
Shih-Ming Lin ◽  
Kathy K.H. Svoboda ◽  
Anthony Giletto ◽  
Jeff Seibert ◽  
Raghunath Puttaiah
Keyword(s):  
Hydrogen Peroxide ◽  
Water Contamination ◽  
Challenge Test ◽  
Control Unit ◽  
Effluent Water ◽  
Municipal Water ◽  
Plate Counts ◽  
Contamination Levels ◽  
Heterotrophic Plate Counts

ABSTRACTObjectives: To study effects of various concentrations of hydrogen peroxide on mature waterline biofilms and in controlling planktonic (free-floating) organisms in simulated dental treatment water systems; and to study in vitro the effects of 2%, 3%, and 7% hydrogen peroxide on the removal of mature biofilms and inorganic compounds in dental waterlines. Methods: Four units of an automated dental unit water system simulation device was used for 12 weeks. All units were initially cleaned to control biofilms and inorganic deposits. H2O2 at concentrations of 1%, 2%, 3% was used weekly for periodic cleaning in three treatment group units (units 1, 2 & 3), with 0.05%, 0.15% and 0.25% H2O2 in municipal water used as irrigant respectively. The control unit (unit 4) did not have weekly cleanings and used municipal water as irrigant. Laser Scanning Confocal Microscopy and Scanning Electron Microscopy were used to study deposits on lines, and weekly heterotrophic plate counts done to study effluent water contamination. A 24 hour in vitro challenge test with 7%, 3% and 2% H2O2 on mature biofilms was conducted using harvested waterlines to study biofilm and inorganic deposit removal. Results: Heterotrophic plate counts of effluent water showed that the control unit reached contamination levels in excess of 400,000 CFU/mL while all treatment units showed contamination levels <500 CFU/mL through most of the 12 weeks. All treatment units showed varying levels of biofilm and inorganic deposit control in this short 12 week study. The in vitro challenge test showed although there was biofilm control, there was no eradication even when 7% H2O2 was used for 24 hours. Conclusions: 2% H2O2 used as a periodic cleaner, and diluted to 0.05% in municipal water for irrigation was beneficial in controlling biofilm and planktonic contamination in dental unit water systems. However, to remove well established biofilms, it may take more than 2 months when initial and multiple periodic cleanings are performed using H2O2. (Eur J Dent 2011;5:47-59)

scholarly journals Evaluation of Microbiological and Free-Living Protozoa Contamination in Dental Unit Waterlines

2019 ◽  
Vol 16 (15) ◽  
pp. 2648 ◽  
Author(s):  
Anna Maria Spagnolo ◽  
Marina Sartini ◽  
David Di Cave ◽  
Beatrice Casini ◽  
Benedetta Tuvo ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Tap Water ◽  
Microbiological Quality ◽  
Coliform Bacteria ◽  
Dental Staff ◽  
Plate Counts ◽  
Dental Unit Waterlines ◽  
Heterotrophic Plate Counts

Studies conducted over the last 40 years have demonstrated that the water output from dental unit waterlines (DUWLs) is often contaminated with high densities of microorganisms. It has been monitored the microbiological quality of the water in 30 public dental facilities in northern Italy in order to assess the health risk for patients and dental staff. In each facility, samples of water both from taps and from DUWLs were analyzed in order to evaluate heterotrophic plate counts (HPCs) at 22 °C and 36 °C, and to detect coliform bacteria, Pseudomonas aeruginosa, Legionella pneumophila and amoebae. In 100% of the samples taken from the DUWLs, the concentration of HPCs was above the threshold as determined by the Ministère de la Santé et des Solidarités (2007). The concentration of P. aeruginosa was greater than the indicated threshold in 16.67% of the hand-pieces analyzed. A total of 78.33% of samples were contaminated by L. pneumophila, while in the samples taken from the DUWLs alone, this percentage rose to 86.67%. Amoebae were detected in 60% of the samples taken from hand-pieces; all belonging to the species V. vermiformis. This study documented the presence of various microorganisms, including Legionella spp., at considerably higher concentrations in water samples from DUWLs than in samples of tap water in the same facilities, confirming the role of the internal DUWLs in increasing microbial contamination, especially in the absence of proper management of waterborne health risks.

scholarly journals Mitigation of Odor, NH3, H2S, GHG, and VOC Emissions With Current Products for Use in Deep-Pit Swine Manure Storage Structures

2020 ◽  
Vol 8 ◽  
Author(s):  
Baitong Chen ◽  
Jacek A. Koziel ◽  
Chumki Banik ◽  
Hantian Ma ◽  
Myeongseong Lee ◽  
...  
Keyword(s):  
Swine Manure ◽  
Pilot Scale ◽  
Scientific Data ◽  
Gaseous Emissions ◽  
Factors Affecting ◽  
Deep Pit ◽  
Wide Range ◽  
Manure Storage ◽  
User Friendly ◽  
Storage Structures

Odorous gas emissions from swine production have been a concern for neighbors and communities near livestock farms. Manure storage is one of the main sources of gaseous emissions. Manure additive products are marketed as a simple solution to this environmental challenge. Manure additives are user-friendly for producers and can be applied (e.g., periodically poured into manure) without changing the current manure storage structure. Little scientific data exist on how these products perform in mitigating gaseous emissions from swine manure. The research objective was to evaluate the effectiveness of 12 marketed manure additives on mitigating odor, ammonia (NH3), hydrogen sulfide (H2S), greenhouse gases (GHG), and odorous volatile organic compounds (VOCs) from stored swine manure. A controlled pilot-scale setup was used to conduct 8-week long trials using manufacturer-prescribed dosages of additives into swine manures. Manure was outsourced from three swine farms to represent a variety of manure storage types and other factors affecting the properties. Measured gaseous emissions were compared between the treated and untreated manure. None of the tested products showed a significant reduction in gaseous emissions when all (n = 3) manures were treated as replicates. Selected products showed a wide range of statistically-significant reduction and generation of gaseous emissions when emissions were compared in pairs of manure types from one farm. The latter observation highlighted the lack of consistent mitigation of gaseous emissions by manure additives. The results of this study do not warrant full-scale trials with the tested products.

scholarly journals Determination of cytotoxicity and invasiveness of heterotrophic plate count bacteria isolated from drinking water

2002 ◽  
Vol 2 (3) ◽  
pp. 115-122 ◽  
Author(s):  
D. Pavlov ◽  
C.M.E. de Wet ◽  
W.O.K. Grabow ◽  
M.M. Ehlers
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Heterotrophic Bacteria ◽  
Penicillin G ◽  
Plate Count ◽  
Heterotrophic Plate Count ◽  
Water Supplies ◽  
Plate Counts ◽  
Study Support ◽  
Heterotrophic Plate Counts

Evidence has been presented that some heterotrophic bacteria often detected in drinking water supplies possess features associated with pathogenicity. This suggests that even the low numbers of heterotrophic bacteria considered acceptable by drinking water specifications may constitute a health risk, particularly to immunocompromised consumers. In this study, 339 bacteria were isolated at random from routine heterotrophic plate count (HPC) tests on selected drinking water supplies in South Africa. In a first screen for potentially pathogenic properties, 188 of the isolates (55.5%) displayed a- or b-haemolysis on blood agar. Further analysis of the haemolytic isolates for enzymes associated with virulence revealed the presence of chondroitinase (5.3%), coagulase (16.0%), DNase (60.6%), elastase (33.0%), fibrinolysin (53.7%), gelatinase (62.2%), hyaluronidase (21.3%), lecithinase (47.9%), lipase (54.8%) and proteinase (64.4%) of the isolates. No fluorescein or pyocyanin was detected in any of the isolates. Among the haemolytic isolates 68.6% were resistant to oxacillin (1 μg), 59.6% to penicillin G (2 units), 47.3% to penicillin G (10 units), 53.7% to ampicillin (10 μg) and 42.6% to ampicillin (25 μg). Cytotoxicity, invasiveness and adherence properties of the haemolytic isolates was determined on HEp-2 and Caco2 cell lines. Among the haemolytic isolates 96% were cytolytic on the HEp-2 cell line. All the haemolytic isolates adhered to HEp-2 and Caco2 cells but gram-negative isolates tended to adhere in larger numbers than gram-positive isolates. HEp-2 cells were invaded by 42% of the haemolytic isolates. Heterotrophic bacteria, which most frequently revealed the above features associated with pathogenicity included species of the following genera: Aeromonas, Acinetobacter, Aureobacterium, Bacillus, Klebsiella, Moraxella, Pseudomonas, Staphylococcus, Tsukamurella and Vibrio. The results obtained in this study support earlier indications that bacteria detected by routine heterotrophic plate counts on drinking water supplies may include bacteria associated with potentially pathogenic properties. The extent to which these bacteria in drinking water supplies may constitute a health risk remains to be investigated.

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