Increase In Bacterial Concentration Research Articles

Bacterial populations in different parts of domestic drinking water systems are distinct and adapted to the given ambient temperatures

Drinking water enters buildings with a given microbiological community composition. Within premise plumbing systems, the drinking water is subject to very different conditions and temperatures. Whereas part of the water stays cold, another part is heated to provide hot water. In this study, drinking water samples were taken at different locations in four buildings that had central heating circles and that were equipped with ultrafiltration modules. The latter were intended to keep bacterial numbers low. When studying the increase in bacterial concentrations in these water samples using regrowth tests at different incubation temperatures, a temperature-dependence could be observed. Bacteria in cold water samples propagated best when incubated at 22°C, but often poorly at 36°C and not at all at 50°C. Bacteria in hot water samples showed the reverse behavior and grew best when incubated at 50°C, whereas growth at 22°C was poor or associated with a long growth lag. Water samples from distal taps in periphery locations used for retrieving both cold and hot water showed intermediate growth behaviors. Results suggest the existence of different temperature-adapted bacterial populations within domestic drinking water systems. The finding was supported by sequence data revealing distinct differences in the microbiomes between cold and hot water samples. Abundant bacterial groups in hot water included Deinococci, Kryptonia, Ignavibacteria, Nitrospiria, Gemmatimonadetes and different genera of Gammaproteobacteria. Stagnation of hot water at 50°C, 55°C, or 60°C furthermore shaped the microbiome in different ways indicating that small temperature differences can have a substantial impact on the bacterial communities.

Bacterial development in semen stored at ambient temperature in INRA96®

Sperm motility and mitochondrial activity can be maintained at room temperature for 24h in INRA96®. However bacterial development remains possible. Furthermore, very few studies evaluated the sensitivity of bacteria to the antibiotics included in INRA96. In experiment 1, semen from 8 stallions (28 ejaculates) was diluted to 20 × 106 sperm/mL in INRA96. The total amount of bacteria, dead or alive, was evaluated using Easykit6® (IMV-Technologies) immediately after dilution, then after 24h and 48h. Bacterial concentration remained stable during 48h cooled storage in Neopor® box (Minitube): mean±sem 9.8±2 × 105, 8.5±2 × 105, 8.4±12 × 105 bacteria/mL at 0h, 24h, 48h, respectively. Bacterial concentration significantly increased after 48h at ambient temperature between 13 and 26°C: 9.7±2 × 105a, 10±2 × 105ab, 28±6 × 105b bacteria/mL at 0h, 24h, 48h, and was significantly higher at ambient temperature than in cooled samples both after 24h and 48h. However, when data were analysed individually, the significant increase occured only for 3 of the 8 stallions. In experiment 2, semen from 7 stallions with 3 ejaculates each was evaluated in duplicate after 0h, 24h and 48h at ambient temperature. Easykit6® showed a significant increase in bacterial concentration for 2 stallions. Conventional bacteriology demonstrated an increase in CFU concentration for 3 stallions including the 2 mentioned above, and a decrease for another stallion. For example, stallion S showed 8±8a, 592±298ab, 8567±4493bCFU/mL at 0h, 24h, 48h, respectively, whereas stallion L showed 1259±504b, 92±53a,117±72aCFU/mL. Sixteen bacterialspecies (38 strains) and one yeast were identified. All the strains of Enterococcus fecalis, Listeria grayi, Streptococcus zooepidemicus, and some strains of Aerococcus viridans, Aeromonas salmonicida, Pasteurella multocida, Pseudomonas sepacia, Staphylococcus hominis, Staphylococcus xylosus, were resistant to both antibiotics of INRA96: 0.028g/L penicillinG and 0.077g/L gentamicin. Ten of the 20 strains identified at 0h and resistant to those antibiotics were not observed anymore at 24h. Eighteen of the 20 strains identified at 48h were resistant to those antibiotics. Eight of them have not been detected at 0h. Candida famata and the 17 bacterial strains identified at 0h and sensitive to those antibiotics were not observed anymore at 24h.The antibiotics and amphotericin B present in INRA96 seem enough to prevent microbial development at ambient temperature, provided that micro-organisms are sensitive to those molecules. Competition occurs between strains: those sensitive to the antibiotics of the extender cannot develop during storage, whereas others, even under the level of detection in raw semen, grow during storage because they are resistant. Bacterial concentration was not significantly correlated with sperm quality (motility, morphological abnormalities). Such bacterial level may not affect spermatozoa. Whether it could induce endometritis in inseminated mares needs investigation. Financial support: IFCE scientific council (Spermicrobes).

Multi-Drugs Resistant Bacteria Associated Particulate Matter In The Ambient Atmosphere of Dhaka, Bangladesh

Nowadays, air pollution is confined to the level of air pollutants and bio-aerosols since it might be pathogenic or induce allergic reactions. The research was carried out to discover the bacteria associated with suspended particulate matter in indoor and outdoor air, as well as to investigate their antibiotic susceptibility. The results revealed that the extent of outdoor air pollutants (i.e., PM2.5, PM10, HCHO, and TVOC) was significantly higher (p< 0.01) than the extent of indoor air pollutants. Culturing the sample filter paper in Nutrient Agar (NA) media at two different temperatures, 25°C and 37°C, allowed us to measure the quantity of bacteria in the air. The concentration of bacteria was 622±22 CFUm-3 at 26±2°C and 11±2 CFUm-3 at 20±2°C in both outdoor and indoor air, respectively. Positive Bacillus, Micrococcus luteus, Pseudomonas stutzeri and Brevundimonas diminuta bacteria were identified. All of the identified bacteria were found to be pathogenic. Moreover, some of the identified bacteria showed resistance to some commercially available antibiotics, such as Cefixime, Ceftazimidine, Nalidixic acid, Ampicillin, Ciprofloxacin, Gentamycin, etc. The positive correlation between fine particles and the bacterial concentration (R2= 0.75 for indoor and R2= 0.68 for outdoor air) revealed that the bacteria were highly associated with fine particles than coarse particles. Furthermore, the number and growth of bacteria were affected by the meteorological parameters (i.e., temperature and relative humidity). The rise in relative humidity favoured the increase in bacterial concentration. Therefore, the risk of being affected by bioaerosol is higher in the wet season than that of the dry season. J. Biodivers. Conserv. Bioresour. Manag. 2021, 7(2): 1-12

Application of MICP in Water Stability and Hydraulic Erosion Control of Phosphogypsum Material in Slope

Phosphogypsum is a kind of solid waste that occupies land resources and harms the environment. It can be used as a solidified material, but the utilization of phosphogypsum is limited by its impurities and weak strength performance. This study aimed to use microbial-induced carbonate precipitation (MICP) to improve the water stability, permeability, and hydraulic erosion resistance of phosphogypsum and evaluate its impact on the environment. In this paper, the phosphogypsum samples and artificial slopes were prepared and solidified by spraying various concentrations of bacteria solution and cementation solution to achieve microbial modification. The water stability and permeability test were used to calculate the mass of spalling under water shaking and the permeability coefficient. A rainfall scouring test was carried out to estimate the erosion resistance. The erosion degree was quantitatively calculated using 3D laser scanning technology. The results show that the microorganism treatment can improve water stability and reduce the permeability coefficient, while the differences between the content of CaCO3 in the outermost layer and in the inner layer gradually increase with the increase in bacterial concentration, and the permeability coefficient was reduced uniformly. The sediment loss of the slope after MICP treatment was much less than that of the untreated slope, and the connection force between the particles was strengthened. By observing the morphology of the scoured samples, we found that the treated particles were aggregated and flocculated with more macropores, which led to the formation of erosion pits under scouring. The pH of the outflow of the modified slope was neutral, and the heavy metal elements were fixed by microbial action and carbonate, which is not harmful to the environment.

A predictive model of the impact of urbanization on bacterial loads in watersheds

Bacterial concentration is one of the most important aspects of water quality. Many regions in the world are affected by increasing urbanization and a potential increase in bacterial concentrations in waters. We used long-term data from 68 stations in eight watersheds in Eastern Thailand to quantify the temporal and geographical variation in total and fecal coliform bacteria. Descriptive statistics showed considerable seasonal, inter-annual, and geographical variation. In order to quantify this multi-level variation, we built a predictive model of bacterial loads. Using fixed- and mixed-effects regression models, we built a model including the effects of urbanization and other significant variables. The best model, fitted by restricted maximum likelihood, included the effects of season, year, urbanization as fixed effects, and of watershed and station as nested, random effects. Temporal variation was related to seasonal and annual variations. Spatial variation had a very significant impact on the bacterial concentrations. Urbanization was an important factor controlling concentrations of bacteria in rivers: we found that the proportion of urban area around a station had a statistically significant effect on log-transformed total coliform bacterial concentration with a slope equal to 1.3 (SE = 0.3), and on log-transformed fecal coliform bacterial concentration with a slope equal to 1.4 (SE = 0.3). Our model predicts that bacterial concentrations would be multiplied by 20 if land is transformed from non-urban to fully urban.

Klebsiella pneumoniae infection inhibits autophagy by alveolar type II epithelial cells.

To investigate the molecular mechanism underlying the interaction between autophagosomes of alveolar type II epithelial (A549) cells and Klebsiella pneumoniae, an in vitro model of K. pneumoniae-infected A549 cells was established. Western blot analysis and immunofluorescence staining were used to detect the distribution of microtubule-associated protein 1A/1B-light chain 3 (LC3) and the expression of the LC3-phosphatidylethanolamine conjugate (LC3-II). K. pneumoniae-infected A549 cells were treated with different concentrations of an autophagy inhibitor or promoter for different time periods to assess the level of autophagy. Western blot analysis and immunofluorescence staining showed that K. pneumoniae could induce autophagy by A549 cells. With an increase in bacterial concentration and time of infection, autophagy gradually increased. The autophagy inhibitor significantly downregulated, while the promoter upregulated, expression of the autophagy-related protein LC3-II. Autophagy plays an important role in the resistance of alveolar type II epithelial (A549) cells to K. pneumoniae infection.

Rapid Detection of <em>Staphylococcus aureus</em> Using Graphene Oxide Coated Screen-Printed Sensor Strips

Staphylococcus aureus ( S. aureus ) is the most common reason behind bacterial infections in humans. They cause a wide array of infections on skin, bone and joint medical implants and blood stream. In order to mitigate these infections, detecting the presence of this bacterium is of prime importance. This paper explores a new rapid detection technique to identify S aureus bacteria. A screen-printed sensor coated with graphene oxide was used as an identification platform. Graphene oxide was synthesized using modified Hummer’s method and was characterized using X-ray Diffractometer and Scanning Electron Microscope. The developed sensors showed significant decrease in the bulk resistance with the increase in bacterial concentrations. The developed sensors were subjected to selectivity, repeatability and reusability tests and showed good results.

Growth Promotion and Immune Stimulation in Nile Tilapia, Oreochromis niloticus, Fingerlings Following Dietary Administration of a Novel Marine Probiotic, Psychrobacter maritimus S.

A 50-day feeding trial was conducted to evaluate the effects of dietary supplementation of a novel marine psychrotrophic bacterium, Psychrobacter maritimus S, on growth performance and immune responses of Nile tilapia (Oreochromis niloticus) fingerlings. Triplicate groups of Nile tilapia (10 fish each) were fed for 50days with three different diets: T0 (without probiotic, negative control), T0.5 (supplemented with 3.3 × 108CFUg-1P. maritimus S), and T1 (supplemented with 6.6 × 108CFUg-1P. maritimus S). The test diets were fed to fish at a daily rate of 3% of their live weights, three times per day. On the 50th day, fish were weighed and blood samples were collected to determine the main nonspecific humoral and cellular immune responses and digestive enzymes (protease, amylase, and lipase). Fish performance (weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and protein productive value) was also calculated. Growth rates and digestive enzyme activity were significantly increased (P < 0.05) with increasing dietary P. maritimus S up to 0.5%, and leveled off with further increase in bacterial concentrations. Phagocytic activity, lysozyme activity, alternative complement hemolysis, and hematological parameters were also significantly increased (P < 0.05) with increasing P. maritimus S concentration to 0.5%, followed by a slight decrease (P > 0.05) at 1% level. The expression of interleukin-4 and interleukin-12 genes was significantly upregulated, while heat shock protein gene was downregulated, with dietary supplementation of P. maritimus S up to 0.5% level. These results suggest that 0.5% of dietary Psychrobacter maritimus S supplementation could be considered as a novel probiont for optimum growth performance and immune response of Nile tilapia fingerlings.

Improvement of the mechanical properties of mortar and concrete using ureolytic bacteria

The construction industry uses cement, the production of which is heavy contributor to carbon dioxide (CO2) emissions and environmental damage. Any method that reduces the usage of cement could thus result in a substantial reduction of the overall carbon dioxide footprint of final cement-based products. In this study, ureolytic bacteria were used to improve the different properties of cement mortar and concrete. Properties such as compressive strength and sorptivity were studied experimentally. The experimental results showed that the compressive strength of both cement mortar and concrete increased with an increase in bacterial concentration due to microbiologically induced mineral precipitation. An optimum bacterial dosage of 107 colony-forming units (CFU)/ml was found for the maximum increase in compressive strength for both mortar and concrete. Capillary water absorption was also found to be lower for the bacterial specimens at the optimum dosage compared with that of the control specimens. Microstructural analysis, X-ray powder diffraction and field emission scanning electron microscopy confirmed the microbiologically induced mineral precipitation.

Biological Stabilization of a Swelling Fine-Grained Soil: The Role of Microstructural Changes in the Shear Behavior

In many engineering projects, improving soil shear strength is one of the goals. There are different methods for soil improvement among which biological soil stabilization techniques have emerged in recent decades. These techniques have been introduced as environmentally friendly techniques and have been shown to give promising results. However, different aspects of their effect on the soil mechanical properties have not yet been comprehensively understood. One of these aspects is the effect of different ingredients such as the effect of culture media as well as bacterial concentration on the improvement in the soil shear strength. In this study, the effect of one of the most commonly used biological stabilization techniques, namely microbial induced calcite precipitation on the shear strength of a swelling fine-grained soil has been studied by means of laboratory-scale tests and the influence of bacterial concentration as well as the chemicals used in the treatment (culture media) have been looked into. The results have been carefully analyzed and presented in terms of suitable formulas for practical purposes. Furthermore, the mechanisms contributing to the shear strength increase have been discussed based on the observed changes in the soil micro-fabric disclosed by X-ray diffraction analysis. The results reveal that by increasing bacterial concentration, the soil cohesion and the soil friction angle increase for which empirical relationships are presented. The increase in bacterial concentration thus increases the soil shear strength. Furthermore, the effect of culture media on the soil mechanical properties is examined. While the sole use of culture media slightly increases the soil shear strength, its impact on the soil shear strength is much less than that of the complete biological solution which includes bacteria. This proves the hypothesis that the improvement is indeed induced by the bio-geo-chemical processes which bacteria bring about rather than the chemical compounds present in the biological solution.

A thin-reflector microfluidic resonator for continuous-flow concentration of microorganisms: a new approach to water quality analysis using acoustofluidics.

An acoustofluidic device has been developed for concentrating vegetative bacteria in a continuous-flow format. We show that it is possible to overcome the disruptive effects of acoustic streaming which typically dominate for small target particles, and demonstrate flow rates compatible with the testing of drinking water. The device consists of a thin-reflector multi-layered resonator, in which bacteria in suspension are levitated towards a glass surface under the action of acoustic radiation forces. In order to achieve robust device performance over long-term operation, functional tests have been carried out to (i) maintain device integrity over time and stabilise its resonance frequency, (ii) optimise the operational acoustic parameters, and (iii) minimise bacterial adhesion on the inner surfaces. Using the developed device, a significant increase in bacterial concentration has been achieved, up to a maximum of ~60-fold. The concentration performance of thin-reflector resonators was found to be superior to comparable half-wave resonators.

Effects of Electric Field Strength on an Antimicrobial Air Filter

We investigated the effects of a surrounding electric field (EF) on the performance of antimicrobial air filters coated with natural-product nanoparticles. The filtration efficiency of the control filter increased with increasing EF strength, whereas the filtration efficiency of the antimicrobial filter did not, probably because its original efficiency was already high (> 99%) and non- or relatively weakly charged bacterial aerosols were hardly affected by EF strength. The bacterial deposition profiles through the depth of the antimicrobial filters were evaluated. The bacterial concentration at depths of 0–68 µm was increased by about 30% at an EF of 7.7 kV/cm compared with the concentration at 0 kV/cm. Scanning electron microscopy revealed that at 7.7 kV/cm, but not at 0 kV/cm, the bacteria formed dendrites on the fibers of the filter, and the concentration of bacteria deposited on the fibers at 7.7 kV/cm was two to three times that at 0 kV/cm. In antimicrobial tests, the performance of the antimicrobial filters increased with increasing concentration of antimicrobial nanoparticles, but the effectiveness differed between 0 and 7.7 kV/cm. At an identical nanoparticle concentration, the inactivation efficiency of the antimicrobial filter at 7.7 kV/cm was at most 23% lower than that at 0 kV/cm, because the relative increase in bacterial concentration and dendrite formation in the first layer of the antimicrobial filter at 7.7 kV/cm reduced the surface contact area between the bacteria and the antimicrobial nanoparticles. This study provides valuable information for developing a hybrid air purification system that serves various functions and can be used in an indoor environment.

Microbial and antibiotic resistant constituents associated with biological aerosols and poultry litter within a commercial poultry house

Poultry are known to harbor antibiotic resistant and pathogenic bacteria, and as such poultry litter and poultry house air can be contaminated with these bacteria. However, the presence of antibiotic resistant bacteria in biological aerosols and litter is largely not understood. The purpose of this study was to determine the amount of aerosolized bacteria and endotoxin, particularly fecal indicators, staphylococci, and enterococci, associated with poultry house and outdoor air. Aerosol samples were collected at multiple locations on the farm and in the house. Antibiotic resistance was investigated using the Kirby Bauer method on selected isolates using twelve different antibiotics spanning both narrow to broad spectrums of effectiveness. Overall there was a cyclical increase in bacterial concentrations as flocks progressed from pre-flock to late-flock, with > 2 orders magnitude lower concentration during pre-flock periods (no chickens), in both the litter and aerosol samples. The house environment provided for significantly concentrated bacterial and endotoxin levels. It was estimated that Staphylococcus bacteria accounted for at least 90% of cultured aerobic bacteria and culture-independent 16S rRNA analyses demonstrated that significant population changes occurred from pre- to late-flock. Rarely was an isolate resistant to more than 4 antibiotic classes; however there was a trend upwards in overall resistance of enterococci as the flock cycle progressed. It appears that although levels of antibiotic resistant bacteria were highly concentrated within the house, levels were much lower outside of the house, and very little house escape occurred.

Microbial Responses Viewer (MRV): A new ComBase-derived database of microbial responses to food environments

ComBase is a large database of microbial responses to food environments and has attracted the attention of many researchers and food processors. Although ComBase contains a vast amount of data, it is not easy to obtain desired information from the retrieved data. In the present study, we developed a new ComBase-derived database (Microbial Responses Viewer, MRV) consisting of microbial growth/no growth data. The response was defined as representing “growth” if a significant increase in bacterial concentration (> 1.0 log 10) was observed. Alternatively, “growth” was defined as a positive value of the specific growth rate. The growth/no growth data of nineteen different microorganisms were extracted from all the data in ComBase comprising 29 kinds of microorganism. Furthermore, the specific growth rate of each microorganism was modelled as a function of temperature, pH, and water activity ( a w) using a Poisson log-linear model, which is a family of generalized linear models (GLMs). For 16 of the 19 microorganisms, the specific growth/death rate was successfully modelled as a function of temperature, pH, and a w using GLM. The specific growth rate was illustrated using a two-dimensional contour plot with growth/no growth data. MRV provides information concerning growth/no growth boundary conditions and the specific growth rates of queried microorganisms. Using MRV, food processors can easily find the appropriate food design and processing conditions. This database will contribute to the efficient and safe production and distribution of processed foods.

Concentration effects of Winogradskyella sp. on the incidence and severity of amoebic gill disease

To study the concentration effects of the bacterium Winogradskyella sp. on amoebic gill disease (AGD), Atlantic salmon Salmo salar were pre-exposed to 2 different doses (10(8) or 10(10) cells 1(-1)) of Winogradskyella sp. before being challenged with Neoparamoeba spp. Exposure of fish to Winogradskyella sp. caused a significant increase in the percentage of AGD-affected filaments compared with controls challenged with Neoparamoeba only; however, these percentages did not increase significantly with an increase in bacterial concentration. The results show that the presence of Winogradskyella sp. on salmonid gills can increase the severity of AGD.

Grazing Characteristics and Growth Efficiencies at Two Different Temperatures for Three Nanoflagellates Fed with Vibrio Bacteria at Three Different Concentrations.

Small inocula of one of the flagellates Paraphysomonas imperforata, Pteridomonas danica, and Cafeteria roenbergensis were added to suspensions of the bacterium Vibrio natriegens at each of three concentrations between 107 and 108 cells ml-1 and incubated at each of the temperatures 10 degrees C and 25 degrees C. Samples were taken at intervals for counting the flagellates and bacteria to determine the timing of the maximum of flagellate numbers and the concentrations at that time. Measurements of the protein concentration of the suspensions during incubation were used to determine the gross growth efficiency (GGE) or yield of flagellate grazing in each experiment. The most effective grazer was Pteridomonas, followed by Paraphysomonas, with Cafeteria being least effective, as judged by the threshold bacterial concentrations at which flagellate multiplication ceased, which were about 2 x 105, 2 x 106, and 2 x 107, respectively, and by the finding that Pteridomonas consumed 99%, Paraphysomonas about 95%, and Cafeteria only 60-70% of the available bacteria in the experiments. Peak concentrations of flagellates were reached later at the lower temperature, but the numbers of flagellates produced and of bacteria eaten were of a similar order at the two temperatures and the GGE was only slightly higher at the lower temperature. The time taken to reach peak flagellate numbers changed little with a threefold increase in bacterial concentrations, but the GGE increased and the numbers of bacteria eaten to produce one flagellate decreased when the bacterial concentration was increased. The three flagellates show clear evidence of niche specialization in differences in thresholds of bacterial prey concentration.

Intrauterine Pressure Catheter in Labor: Associated Microbiology

Objective: The purpose of this study was to determine if bacterial growth occurred in the amniotic fluid of laboring women. Twenty patients who required an intrauterine pressure catheter (IUPC) during labor were studied. Amniotic fluid samples were aspirated during labor and at the time of delivery. Methods: IUPCs were placed in laboring patients for a variety of reasons. Cervical cultures were taken prior to insertion of an IUPC. After the IUPC was placed, amniotic fluid cultures were taken both at the time of placement and 30 minutes prior to delivery. These cultures were sent for aerobic, anaerobic, Mycoplasma, and Ureaplasma cultures. Results: The increase in bacterial concentration from the initial sample to the final sample was statistically significant (P < 0.01) for both aerobes and anaerobes. Amniotic fluid samples demonstrated a median of 0 bacterial species per patient on initial collection and 2 bacterial species per patient in final collection. The mean count of cfu for erobes in the initial amniotic samples was 3.5 × 104, compared to that of the second samples, which was 1.4 × 105. The mean count of cfu for anaerobes in the initial amniotic fluid samples,.was 4.1 × 102, compared to that of the second samples, which was 8.0 × 103. Only 3 of 20 patients developed chorioamnionitis, with only 1 patient having an increased number ofbacterial species significantly higher than the median. Although 80% of patients had a colony count ≥ 102 cfu/cc, only 19% of this group developed chorioamnionitis. Conclusions: The number of bacterial species and colony counts increased significantly during labor, but this factor alone was not enough to cause chorioamnionitis in a significant number of patients.

Detection of a Vibrio sp. by the bacteriophagous nematode Pelodera chitwoodi.

Summary. Pelodera chitwoodi was able to distinguish between a Vibrio sp. (food bacterium) and Chromobacterium janthinum (non‐food bacterium), and between bacteria and mud. Nematodes migrated preferentially to the Vibrio sp. at various distances, temperatures, and pH values. Migration to food bacteria increased with an increase in bacterial concentration. Resting and dead bacteria failed to attract nematodes. Nematodes were able to detect a vibrio colony separated from them by a plastic barrier, and migrated to areas on agar containing exudate and dialysate from the vibrio. Both exudate and dialyzate contained 4 amino acids and 3 vitamins which attracted nematodes. However, attraction of nematodes to these compounds was not as strong as to metabolizing bacteria, indicating that additional compounds were also involved.