High Concentrations Of Bacteria Research Articles

Associative analysis of sludge microbiota and wastewater degradation efficacy within swine farm sludge systems

Industrial wastewater management is a significant global challenge. Sludge microbiota from swine farms may play a crucial role in enhancing wastewater treatment processes, thereby reducing water pollution from industrial activities. A deeper understanding of this complex community could lead to innovative approaches for improving wastewater treatment methods. Sludge samples were collected from the anaerobic, sedimentation, and thickening tanks of ten swine farms. The microbiota communities were analyzed using 16S rRNA full-length sequencing on the PacBio platform, with subsequent data analysis conducted on the QIIME2 platform utilizing the SILVA database. Compared to anaerobic and thickening tanks, the sedimentation tanks exhibited a unique profile of sludge microbiota, with higher abundances of the phyla Proteobacteria, Bacteroidota, and Caldatribacteriota. Additionally, sludges from farms already utilized in processing industrial water—specifically farms B, G, and J—contained higher concentrations of bacteria (> 20 ng/μL), indicating the robustness of the bacterial load for practical industrial use. Furthermore, sludge from farms with higher alpha diversity, such as E, G, I, and J, exhibited enriched degradation profiles, including the degradation of aromatic compounds, polymers, industrial compounds, toluene, and vanillin. The farms were categorized based on wastewater ammonia nitrogen degradation levels, revealing a clustering effect of the microbiota from the sedimentation tanks in the Principal Coordinates Analysis (PCoA) plot. A higher relative abundance of the families Rhodocyclaceae, AKYH767, and Comamonadaceae, and a lower abundance of the families Anaerolineaceae and Christensenellaceae, were found in groups with high ammonia nitrogen reduction, suggesting potential targets for bioaugmentation strategies. In conclusion, this study underscores the critical role of microbial abundance, composition, and biodiversity in optimizing wastewater treatment and advocates for comprehensive microbiota analysis to identify suitable sludge for industrial applications.

Relationships between fecal indicator abundance in water and sand and the presence of pathogenic genes in sand of recreational beaches.

For decades, the risk of exposure to infectious diseases in recreational beaches has been evaluated through the quantification of fecal indicator bacteria in water samples using culture methods. The analyses of sand samples have recently been developed as a complement to the monitoring of recreational waters in beach quality assessments. The growing use of molecular techniques for environmental monitoring allows for the rapid detection of pathogenic genes, thus providing more accurate information regarding the health risk of exposure to contaminated sand. The aim of this work was to determine the relationship between the fecal indicators abundance in water and sand and the presence of Shiga toxin-producer Escherichia coli (STEC) in sand by analyzing samples from touristic beaches using culture-dependent (fecal coliforms assay) and culture-independent (real-time PCR of stx1, stx2, and eae genes) techniques. We found a high concentration of coliform bacteria in water and sand in several beaches in eastern Uruguay, with different levels of sanitation networks and levels of urbanization. The presence of STEC virulence genes (mainly stx1) was confirmed in 8 out of 20 sand samples. The recreational use of sandy beaches may imply a risk to the health of its users, especially near streams and creek outflows, thus highlighting the need of monitoring sand bacteriological quality and pathogens using molecular tools.

Label-free electrochemical immunosensor for rapid and highly sensitive detection of Brucella abortus in serum

Accurate and efficient detection of Brucella is crucial to control the disease and mitigate its impact on animal health and human safety. In this study, a simple and rapid label-free electrochemical immunosensor for the detection of Brucella abortus was fabricated based on the principle of current decrease after specific capture of the bacteria. A certain proportion of multi-walled carbon nanotubes (MWCNTs), dopamine hydrochloride (DA), and gold nanoparticles (AuNPs) were modified on the surface of a gold disc electrode. Then, Brucella abortus antibody and bovine serum albumin (BSA) were immobilized in sequence to complete the assembly of the sensor. The electrodes from various assembly steps were characterized by a cyclic voltammetry (CV) curve. The immunosensor exhibited high sensitivity with a wide linear range between 10 CFU/mL and 108 CFU/mL. Additionally, the sensor displayed good repeatability, stability, and interference resistance. The recovery rates for low, medium, and high concentrations of bacteria were all within the range of 90 % to 100 %, indicating a high level of accuracy. The method established in this study can provide reference and assistance for early diagnosis of Brucella abortus in clinical practice.

Reducing moisture content can promote the removal of pathogenic bacteria and viruses from sheep manure compost on the Qinghai-Tibet Plateau

Livestock manure contains a high concentration of pathogenic bacteria, viruses, and other harmful microorganisms. The effective elimination of these pathogens is of great significance to the harmless and resource utilization of livestock and poultry manure. Building upon prior research, this study further explored the removal efficiency of pathogenic bacteria and viruses in sheep manure compost on Qinghai-Tibet Plateau under 45 % (M45) and 60 % (M60) moisture content. The results showed that M45 led to a significant increase in the average composting temperature (P＜0.05), a notable reduction in the levels of Salmonella and Coliforms in the compost products, and facilitated the decline in abundance of various pathogens. As composting progressed, the abundance of viruses declined rapidly. Uroviricota was the most dominant viral phylum, and Siphoviridae, Myoviridae, Herpesviridae, and Podoviridae as the predominant viral families. M45 can significantly reduce the diversity and abundance of compost virus community (P＜0.05). The correlation analysis indicated a negative relationship between pathogens and the average temperature and humus content of the compost. In summary, the reduction of moisture content can enhance the biosafety of sheep manure compost products on the Qinghai-Tibet Plateau. These findings provide theoretical basis and technical support for the harmless and resource utilization of sheep manure waste on the Qinghai-Tibet Plateau.

A Clean and Health-Care-Focused Way to Reduce Indoor Airborne Bacteria in Calf House with Long-Wave Ultraviolet.

Long-term exposure to a relatively high concentration of airborne bacteria emitted from intensive livestock houses could potentially threaten the health and welfare of animals and workers. There is a dual effect of air sterilization and promotion of vitamin D synthesis for the specific bands of ultraviolet light. This study investigated the potential use of A-band ultraviolet (UVA) tubes as a clean and safe way of reducing airborne bacteria and improving calf health. The composition and emission characteristics of airborne bacteria were investigated and used to determine the correct operating regime of UVA tubes in calf houses. Intermittent exceedances of indoor airborne bacteria were observed in closed calf houses. The measured emission intensity of airborne bacteria was 1.13 ± 0.09 × 107 CFU h-1 per calf. Proteobacteria were the dominant microbial species in the air inside and outside calf houses. After UVA radiation, the indoor culturable airborne bacteria decreased in all particle size ranges of the Anderson sampler, and it showed the highest reduction rate in the size range of 3.3-4.7 μm. The results of this study would enrich the knowledge of the source characteristics of the airborne bacteria in intensive livestock farming and contribute to the environmental control of cattle in intensive livestock production.

Fixation of high concentration CO2 using Chlorella – Bacteria symbiosis system

The mutualistic interaction between microalgae and bacteria provides a new strategy for improving carbon fixation by microalgae. In this study, Chlorella was co-cultured with natural flora at 15 % (v/v) CO2 concentration for 120 d. Three Chlorella symbiotic bacteria strains were identified and were co-cultured with Chlorella vulgaris HL02 (C. vulgaris HL02) to fix high concentrations of CO2. The results showed that the symbiotic bacteria significantly enhanced the fixation of 15 % CO2 by Chlorella, with C. vulgaris HL02 + Aeromonas GS-HL01 having the highest carbon fixation efficiency, which was 22.31 % higher than that of the sterile control, followed by C. vulgaris HL02 + Bacillus GS-F03, and C. vulgaris HL02 + Microbacterium GS-H02 (which was also 16.36 % higher than the sterile control). The composition of harvested Chlorella was not altered significantly following co-culturing with bacteria. Scanning electron microscopy and Excitation–emission matrix spectra analyses showed that at high concentrations of CO2, Microalgae and bacteria promote mutual growth and CO2 fixation mainly through extracellular secretion of organic matter. Our results provided a new strategy to improve the efficiency of microalgae in fixing high concentration of CO2.

Characteristics and health impacts of bioaerosols in animal barns: A comprehensive study

Bioaerosols produced during animal production have potential adverse effects on the health of workers and animals. Our objective was to investigate characteristics, antibiotic-resistance genes (ARGs), and health risks of bioaerosols in various animal barns. Poultry and swine barns had high concentrations of airborne bacteria (11156 and 10917 CFU/m3, respectively). Acinetobacter, Clostridium sensu stricto, Corynebacterium, Pseudomonas, Psychrobacter, Streptococcus, and Staphylococcus were dominant pathogenic bacteria in animal barns, with Firmicutes being the most abundant bacterial phylum. Based on linear discriminant analysis effect size (LEfSe), there were more discriminative biomarkers in cattle barns than in poultry or swine barns, although the latter had the highest abundance of bacterial pathogens and high abundances of ARGs (including tetM, tetO, tetQ, tetW sul1, sul2, ermA, ermB) and intI1). Based on network analyses, there were higher co-occurrence patterns between bacteria and ARGs in bioaerosol from swine barns. Furthermore, in these barns, relative abundance of bacteria in bioaerosol samples was greatly affected by environmental factors, mainly temperature, relative humidity, and concentrations of CO2, NH3, and PM2.5. This study provided novel data regarding airborne bio-contaminants in animal enclosures and an impetus to improve management to reduce potential health impacts on humans and animals.

Effect of Sulphate-Reducing Bacteria Activity on the Performance of Thermally Sprayed Aluminium and Polyurethane Coatings

In the present work, we studied whether the exposure of synthetic seawater with anaerobic sulphate-reducing bacteria (SRB) on some steel samples generates a bacterial biofilm in their surfaces. Bare steel belonging to a mooring chain as well as two coating systems applied on the steel surface were studied: polyurethane (PU) and thermally sprayed aluminium (TSA) with and without an epoxy-based sealant. After 30 days of immersion in SRB-inoculated synthetic seawater, a bacterial count was attained, and the samples were observed using scanning electron microscopy (SEM) and locally analysed using X-ray scattered energy spectroscopy (EDS). A biofilm developed on every tested surface (continuous or in the form of pustules), with evidence of metabolic activity of the SRB. Finally, a mechanism of degradation for TSA in the presence of SRB is proposed for environments with a high concentration of bacteria.

Contamination of Fish Feed with Pathogenic Organisms: Implications on Fish Diseases in Aquaculture Systems

Tracing contamination to its ultimate source is considered difficult as multiple factors affect stable microbial community in culture water. Feed, covering over 60 percent of production cost although less considered, could represent a significant source of fish diseases, the major constraint in aquaculture production. The present study based on the sensitivity of quantitative Polymerase Chain Reaction, indicated low to high concentrations of bacteria and fungi in fish-feed from various aquaculture farms in Ghana. Prevalence rate of bacteria isolated from the gut of fish (26.09%) were similar to that from diseased portions (26.89%). Although mode of transmission of most infections are largely through the water in which the fish are submerged, Staphylococcus aureus was not isolated from the culture water samples but occurred with the highest prevalence (60%) in fish-feed, thus confirming contamination of fish-feed as a significant pathway for entry of pathogens. Advancements towards the safety of fish should include the surveillance of fish-feed for microbial quality, and incorporation into human foodborne disease surveillance systems to ensure holistic effectiveness.

Characterization of four digestates from different types of substrates used in biogas production in Northern Peru

Background Biol is one of the best-known digestates, which occurs during anaerobic digestion in biodigesters to generate biogas, using animal manure and vegetable waste. This digestate type is used in organic agriculture due to its easy application, contributing simultaneously to the circular economy and food security. Methods The objective of this study was to characterize four types of biol, generated in four anaerobic biodigesters for biogas production implemented in northern Peru fed with manure: i) pig manure; ii) cattle manure; iii) horse manure; iv) cattle manure with coffee processing water. All the biodigesters implemented had the same design but worked under different environmental conditions. Descriptive and multivalent statistics were applied to the data obtained for the parameters evaluated. Results The biols obtained had different nutritional compositions, depending on the type of substrate used. The biol from pig manure was characterized by high concentrations of bacteria, the one from cattle manure had low concentrations of nutrients in general, the one from horse manure was rich in salts, and the one from cattle manure with coffee processing water was rich in organic matter. Conclusions These results showed that all the biols obtained can be used for organic agriculture. However, their selection will depend on the nutritional requirements of the type of crop and soil where the biols are to be applied.

Influence of phosphate on bacterial release from activated carbon point-of-use filters and on biofilm characteristics

Point-of-use (POU) filters certified to remove lead are often composed of activated carbon and have been shown to release high concentrations of bacteria, including opportunistic pathogens. In this study, we examine the impacts of the common corrosion inhibitor phosphate on biofilm characteristics and the relationship between biofilm structure and bacterial release from POU filters. This knowledge is essential for understanding how best to use the filters and where these filters fit in a system where other lead contamination prevention measures may be in place. We measured the bacterial release from activated carbon POU filters fed with groundwater - a common source of drinking water - with and without phosphate. We used optical coherence tomography (OCT) to quantitatively characterize biofilm growing on activated carbon filter material in which the biofilms were fed groundwater with and without phosphate. Phosphate filters released significantly less (57–87 %) bacteria than groundwater filters, and phosphate biofilms (median thickness: 82–331 μm) grew to be significantly thicker than groundwater biofilms (median thickness: 122–221 μm). The phosphate biofilm roughness ranged from 97 to 142 % of the groundwater biofilm roughness and was significantly greater in most weeks. Phosphate biofilms also had fewer pores per biofilm volume and shorter channels connecting those pores.

Bacteriological Assessment of Indoor Air Quality in Keystone (Male) Hostel, University of Benin, Benin City

This study examined and identified the level of bacteria present in the hostel to evaluate the potential health hazards for the residents and establish guidelines for controlling indoor air quality. Six (6) rooms were sampled out of 25 rooms at the keystone hostel, each with a height of 10 feet, and an average dimension of 9 feet by 10 feet. The study was done in July and November, 2023. Passive air sampling of settle plate method was employed. The isolates were identified using standard cultural and biochemical identification method. The outcome revealed that the concentration of bacteria isolates rose as media exposure time increased. In July, the maximum bacteria concentration was observed in room 37 at 20min (21.5 x 102CFU/m3) and the minimum in room 49 at 20 min (0.02 x 102 CFU/m3. The concentration of bacteria in room 48 at 20 min was (0.1 x 102 CFU/m3), room 47 at 20 min (11.0 x 102 CFU/m3), room 38 at 20 min (16.5 x 102 CFU/m3), room 39 at 20 min (10.5 x 102 CFU/m3), While for the month of November, the highest bacteria concentration was seen in room 37 at 20min (26.5 x 102 CFU/m3) and the least at room 49 at 20 min (0.09 x 102 CFU/m3). The concentration of bacteria at other room 48 at 20 min (0.3 x 102 CFU/m3), room 47 at 20 min (13.5 x 102 CFU/m3), room 38 at 20 min (19.2 x 102 CFU/m3), room 39 at 20 min (15.1 x 102 CFU/m3). A total of seven (7) distinct bacteria species: Escherichia coli (60%), Staphylococcus aureus (100%), Streptococcus pyogenes (50%), Bacillus cerus (30%), Seratia marcescens (30%), Klebsiella spp (50%) and Proteus spp (50%) were isolated and identified in four rooms ( 37, 38, 39, and 47), with six occupants each, while room 48 and 49 had two occupants respectively; hence bacterial load were relatively non-significant. However, Staphylococcus aureus, Streptococcus pyogenes and Bacillus cerus were identified as the most pathogenic isolates seen in the rooms under study. The study highlights the potential impact of occupancy levels on microbial presence within indoor spaces. The results shows that students in rooms 37, 38, 39 and 47 have a high risk of health and disease implications due to poor ventilation and overcrowding, unlike the students in rooms 48 and 49 with low risk of infectious diseases. Therefore, the study recommends a periodic indoor air quality assessment in the students’ hostel, implementation of good health hygiene practices, maintaining environmental sanitation and managing the environmental factors that supports the multiplication of the bacteria especially in the dry season are crucial to preventing the spread of diseases in the hostel.

Indoor air quality improvement with filtration and UV-C on mitigation of particulate matter and airborne bacteria: Monitoring and modeling

Indoor air, especially with suspended particulate matter (PM), can be a carrier of airborne infectious pathogens. Without sufficient ventilation, airborne infectious diseases can be transmitted from one person to another. Indoor air quality (IAQ) significantly impacts people's daily lives as people spend 90% of their time indoors. An industrial-grade air cleaner prototype (filtration + ultraviolet light) was previously upgraded to clean indoor air to improve IAQ on two metrics: particulate matter (PM) and viable airborne bacteria. Previous experiments were conducted to test its removal efficiency on PM and airborne bacteria between the inlet and treated air. However, the longer-term improvement on IAQ would be more informative. Therefore, this research focused on quantifying longer-term improvement in a testing environment (poultry facility) loaded with high and variable PM and airborne bacteria concentrations. A 25-day experiment was conducted to treat indoor air using an air cleaner prototype with intermittent ON and OFF days in which PM and viable airborne bacteria were measured to quantify the treatment effect. The results showed an average of 55% reduction of total suspended particulate (TSP) concentration between OFF days (110 μg/m3) and ON days (49 μg/m3). An average of 47% reduction of total airborne viable bacteria concentrations was achieved between OFF days (∼3200 CFU/m3) and ON days (∼2000 CFU/m3). A cross-validation (CV) model was established to predict PM concentrations with five input variables, including the status of the air cleaner, time (h), ambient temperature, indoor relative humidity, and day of the week to help simulate the air-cleaning effect of this prototype. The model can approximately predict the air quality trend, and future improvements may be made to improve its accuracy.

Association Between Air Microbiological Exposure With Sick Building Syndrome (SBS) among College Dormitory Students in Public University

Introduction: Microbiological pollutants in indoor air can lead to sick building syndrome (SBS). A conducive academic environment in university dormitories requires healthy indoor air quality to enhance student performance. This study aimed to determine the association between indoor air microbiological exposure and SBS among college dormitory students at a public university. Methods: A cross-sectional study was conducted among 112 male and female college dormitory students who stayed in the public university dormitory for more than three months. Respondents were given a self-administered questionnaire-based NIOSH Indoor Environmental Quality Survey. 14 houses were selected for the measurement of indoor air quality which included PM2.5, PM10, relative humidity (%), temperature (°C), air velocity (m/s), indoor bacterial concentration (cfu/m3), and indoor mould concentration (cfu/m3). Results: Higher percentages of SBS symptoms were reported among female (94.6%) college dormitory students compared to male (82.1%). A significant difference in itching symptom on the arms and forearms was found among individuals of different genders (p<0.05). Indoor air parameters such as temperature (OR = 2.56, 95% CI = 2.66-9.87), relative humidity (OR = 1.77, 95% CI = 1.54 – 5.79), indoor bacteria concentration (OR=2.28, 95% CI = 2.48 – 10.93), and indoor mould concentration (OR=2.59, 95% CI = 1.75 – 8.98) were significantly associated with the recent SBS symptoms. Multiple logistic regression showed that the most significant predictor of SBS was indoor mould concentration. Conclusion: Exposure to high concentrations of indoor bacteria and mould, high temperatures, and high relative humidity influenced the prevalence of SBS among college dormitory students. Further assessment and preventive action need to be taken to reduce the exposure of indoor air microbiological to the students.

Longitudinal examination of urine pH, specific gravity, protein, culture, and antimicrobial resistance profiles in healthy dogs.

Urine is routinely evaluated in dogs to assess health. Reference ranges for many urine properties are well established, but the scope of variation in these properties over time within healthy dogs is not well characterized. Longitudinally characterize urine properties in healthy dogs over 3 months. Fourteen healthy client-owned dogs. In this prospective study, dogs were evaluated for health; then, mid-stream free-catch urine was collected from each dog at 12 timepoints over 3 months. Urine pH, urine specific gravity (USG), protein, cultures, and antimicrobial resistance profiles were assessed at each timepoint. Urine pH varied within and between dogs over time (Friedman's test: within P = .03; between P < .005). However, USG, protein, and bacterial diversity of urine were consistent within dogs over time, and only varied between dogs (Kruskal-Wallis: between all P < .005). Antimicrobial resistant isolates were identified in 12 out of 14 dogs with 34 of 48 of the isolates demonstrating resistance to amoxicillin. Urine pH should be assessed at multiple timepoints via pH meter before making clinical decisions. Mid-stream free-catch urine with high concentrations of bacteria (>105 CFU/mL) should not be considered the only indicator of urinary tract infection. Bacterial isolatesfrom dogs in this study had widespread resistance to amoxicillin/oxacillin underscoring the need for antimicrobial stewardship.

Role of suspended solids on the co-precipitation of pathogenic indicators and antibiotic resistance genes with struvite from digested swine wastewater

Struvite recovered from wastewater contains high concentration of fecal indicator bacteria (FIB), porcine adenoviruses (PAdV) and antibiotic resistance genes (ARGs), becoming potential resources of these microbial hazards. Understanding the precipitation behavior of pathogenic indicators and ARGs with suspended solids (SS) will provide the possible strategy for the control of co-precipitation. In this study, SS was divided into high-density SS (separated by centrifugation) and low-density SS (further separated by filtration), and the role of SS on the co-precipitation of FIB, PAdV and ARGs was investigated. The distribution analysis showed that 35.5–73.0% FIB, 79.6% PAdV and 64.5–94.8% ARGs existed in high-density SS, while the corresponding values were 26.9–64.4%, 11.7% and 3.5–24.3% in low-density SS. During struvite generation, 82.7−96.9% FIB, 75.5% PAdV and 56.3–86.5% ARGs were co-precipitated into struvite. High-density SS contributed 20.7−68.5% FIB, 63.9% PAdV and 38.7–87.2% ARGs co-precipitation, and the corresponding contribution of low-density SS was 31.4−79.2%, 3.9% and 6.2–54.7%. Moreover, the precipitated SS in struvite obviously decreased inactivation efficiency of FIB and ARGs in drying process. These results provide a potential way to control the co-precipitation and inactivation of FIB, PAdV and ARGs in struvite through removing high-density SS prior to struvite recovery.

An esterase activity-based biosensor for rapid and sensitive detection of viable Escherichia coli O157:H7 in milk

Escherichia coli O157:H7 is harmful to humans by producing toxins that cause thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome. Real-time recombinase-aided amplification (rRAA) can generate real-time fluorescence signals to achieve sensitive detection of pathogens within 20 min but cannot distinguish dead bacteria from viable bacteria, leading to false-positive results. Thiazole orange monoazide (TOMA) is an activity-labile nucleic acid-modifying compound, permeating into bacterial cells and, in dead cells, covalently linking to genomic DNA to suppress DNA amplification. In viable cells, however, TOMA is cleaved by active esterase and so inhibition of DNA amplification would not occur. A rRAA assay integrated with TOMA was successfully developed potentially enabling rapid and sensitive identification of viable E. coli O157:H7 in milk. The limit of detection was less than 10 cfu mL−1 in both pure culture and skimmed milk. Moreover, this assay could resist interference from non-target bacteria and high concentrations of dead bacteria.

Human wastewater tracking in tropical Hawaiian island streams using qualitative and quantitative assessments of combined fecal indicating bacteria and sucralose, an organic micropollutant of emerging concern

Prevalence of cesspools on tropical islands suggests that high concentrations of enteric bacteria in streams and coastal waters are an indicator of groundwater contamination by human wastewater. But enterococci bacteria may also be from homeothermic animals common to these watersheds or bacteria living in sediments. Sucralose, a manufactured chemical not destroyed in passage through the human gut, cesspools, septic systems, or wastewater treatment facilities, was used to test for the presence of human wastewater in streams on the island of Kauai, Hawaii. Effluent from six municipal wastewater treatment plants showed an average concentration of 39,167 ng/L of sucralose, roughly back-calculated to 9 ng/L per person, enough to present itself in cesspool effluent contaminated waters. Of 24 streams tested, 79% were positive for sucralose at least once in four sets of sampling. All streams tested positive for enterococci bacteria above established standards. Serial testing of the pair of indicators in the same location over time and applying the Multiplication Rule to the independent samples provide a probabilistic certainty level that the water is chronically polluted by human waste. When repeatedly paired with tests for enterococci, sucralose testing is a cost-effective means for assessing human health risk and for developing proper waste management programs that has been underutilized in under-developed tropical and island settings.

Efficacy of UV and UV-LEDs Irradiation Models for Microbial Inactivation Applicable to Automated Sterile Drug Compounding

LEDs development has attracted attention over conventional mercury lamps for the tiny size, high efficiency, long lifetime, low operating temperature. The antimicrobial effectiveness of traditional UV-lamps radiation (wavelength of 254 nm) compared to UV-C LEDs (LED1 wavelength range 275–286 nm and LED2 range 260–270 nm) was carried out, for possible applications to automated sterile drug compounding. The UV lamp and the tested UV-LED devices remarkably reduced microbial load, following a time-dose response, but the best performance was evidenced by LED1, which guaranteed the complete inactivation of high concentrations of bacteria, yeasts, and spores at doses between 200 and 2000 J/m2.

Microfluidic isothermal amplification strategy coupled with improved propidium monoazide (PMAxx) for rapid detection of six viable foodborne pathogens

Based on the combination of the centrifugal microfluidic chip, programable loop-mediated isothermal amplification (pLAMP), and improved propidium monoazide (PMAxx), a new method called PMAxx-mpLAMP was developed for the quantitative determination of six viable foodborne pathogens in real food samples. Specific target genes and primers were designed and verified, and the PMAxx conditions were optimized. Treatment with PMAxx before pLAMP eliminated false-positive outcomes from dead bacteria and identified viable target bacteria with good specificity and sensitivity. The PMAxx-mpLAMP strategy could detect approximately 102 ∼ 103 CFU/mL pathogens without any pre-enrichment and 101 CFU/mL after a short period of enrichment. In addition, the PMAxx-mpLAMP strategy was performed in the presence of a high concentration of dead bacteria and non-target bacteria. Therefore, the established PMAxx-mpLAMP strategy in this study has potential value for the rapid and sensitive detection of foodborne pathogens.