Liquid Enrichment Research Articles

Molecular diagnosis of E.coliO157:H7 Which Isolated from Children with Diarrhea by using Multiplex PCR

A total of 96 stool samples were collected from children with bloody diarrhea from two hospitals in Baghdad. All samples were surveyed and examined for the presence of the Escherichia coli O157:H7 and differentiate it from other Non -Sorbitol Fermenting Escherichia coli (NSF E. coli). The Bacterial isolates were identifed by using morphological diagnostic methods, Samples were cultured on liquid enrichment medium, incubated at 37C? for 24 hrs, and then cultured on Cefixime Tellurite -Sorbitol MacConkey Agar (CT- SMAC). 32 non-sorbitol fermenting bacterial isolates were obtained of which 11 were identified as Escherichia coli by using traditional biochemical tests and API20E diagnostic system without differentiation between serotype O157:H7 and other NSF E. coli isolates . Four special biochemical tests were done for serotype O157:H7 differentiation from other NSF bacteria. Only 3 isolates belonging to the serotype O157:H7 were obtained . Latex agglutination test for O157 and H7 showed that the 3 isolates gave positive results with both tests. The Bacterial isolates were identifed by using Multiplex Polymerase Chain Reaction (MPCR) technology for the presence or absence of 4 genes (Stx1, Stx2, hlyA and eaeA) that encode for main virulence factors to diagnose E. coli O157:H7 isolated By using specific primers in MPCR . The result showed that one E. coli O157:H7 isolates contain all 4 genes , other isolates contain 3 genes: Stx2, hlyA & eaeA.

Temperature lowering of liquid nitrogen via injection of helium gas bubbles improves the generation of parahydrogen-enriched gas.

The para spin isomer of hydrogen gas possesses high nuclear spin order that can enhance the NMR signals of a variety of molecular species. Hydrogen is routinely enriched in the para spin state by lowering the gas temperature while flowing through a catalyst. Although parahydrogen enrichments approaching 100% are achievable near the H2 liquefaction temperature of 20 K, many experimentalists operate at liquid nitrogen temperatures (77 K) due to the lower associated costs and overall simplicity of the parahydrogen generator. Parahydrogen that is generated at 77 K provides an enrichment value of ~51% of the para spin isomer; while useful, there are many applications that can benefit from low-cost access to higher parahydrogen enrichments. Here, we introduce a method of improving parahydrogen enrichment values using a liquid nitrogen-cooled generator that operates at temperatures less than 77 K. The boiling temperature of liquid nitrogen is lowered through internal evaporation into helium gas bubbles that are injected into the liquid. Changes to liquid nitrogen temperatures and parahydrogen enrichment values were monitored as a function of helium gas flow rate. The injected helium bubbles lowered the liquid nitrogen temperature to ~65.5K, and parahydrogen enrichments of up to ~59% were achieved; this represents an ~16% improvement compared with the expected parahydrogen fraction at 77 K. This technique is simple to implement in standard liquid nitrogen-cooled parahydrogen generators and may be of interest to a wide range of scientists that require a cost-effective approach to improving parahydrogen enrichment values.

Efficacy and phytotoxicity of various thiabendazole and tebuconazole ratios in a fungicidal mordant

When developing combined preparations, a possible phytotoxic effect should be considered, depending on the dose of the mordant. Fusarium oxysporum and Pyrenophora graminea strains were cultured in a liquid enrichment culture with the addition of fungicides at a concentration of 1.5; 2.5; 3.3 ppm. Wheat grains of the Avesta variety were treated with thiabendazole and tebuconazole in the following doses: 20 g a.d./ t, 30 g a.d./t, 60 g a.d./t, 80 g a.d./t, 100 g a.d./t of grain. The effectiveness of tebuconazole and thiabendazole on mycelium growth slightly depended on their concentration. A.d. mutually reinforced each other. The synergism of the action of two a.d. is revealed. The analysis of variance showed that the effect of tebuconazole was greater than the thiabendazole effect. For both strains, the optimal ratios of tebuconazole and thiabendazole are 1.5:2.5 ppm. The addition of salicylic acid is effective at ratios of 2.5:0 and 2.5:3.3. The mixture of thiabendazole and tebuconazole reduced the germination energy of the grains mainly due to the appearance of abnormal seedlings. A composition of active substances for seed etching is proposed, including the following ratios of components, pts. wt.: tebuconazole 20-100, thiabendazole 20-150.

Andean soil-derived lignocellulolytic bacterial consortium as a source of novel taxa and putative plastic-active enzymes

An easy and straightforward way to engineer microbial environmental communities is by setting up liquid enrichment cultures containing a specific substrate as the sole source of carbon. Here, we analyzed twenty single-contig high-quality metagenome-assembled genomes (MAGs) retrieved from a microbial consortium (T6) that was selected by the dilution-to-stimulation approach using Andean soil as inoculum and lignocellulose as a selection pressure. Based on genomic metrics (e.g., average nucleotide and amino acid identities) and phylogenomic analyses, 15 out of 20 MAGs were found to represent novel bacterial species, with one of those (MAG_26) belonging to a novel genus closely related to Caenibius spp. (Sphingomonadaceae). Following the rules and requirements of the SeqCode, we propose the name Andeanibacterium colombiense gen. nov., sp. nov. for this taxon. A subsequent functional annotation of all MAGs revealed that MAG_7 (Pseudobacter hemicellulosilyticus sp. nov.) contains 20, 19 and 16 predicted genes from carbohydrate-active enzymes families GH43, GH2 and GH92, respectively. Its lignocellulolytic gene profile resembles that of MAG_2 (the most abundant member) and MAG_3858, both of which belong to the Sphingobacteriaceae family. Using a database that contains experimentally verified plastic-active enzymes (PAZymes), twenty-seven putative bacterial polyethylene terephthalate (PET)-active enzymes (i.e., alpha/beta-fold hydrolases) were detected in all MAGs. A maximum of five putative PETases were found in MAG_3858, and two PETases were found to be encoded by A. colombiense. In conclusion, we demonstrate that lignocellulose-enriched liquid cultures coupled with genome-resolved metagenomics are suitable approaches to unveil the hidden bacterial diversity and its polymer-degrading potential in Andean soil ecosystems.

Detection of Clostridium perfringens in donor milk at a human breast milk bank: a case report

BackgroundThe breast milk bank is a professional organization that collects donor human milk (DHM) for special medical needs by recruiting qualified breast milk donors. Such organizations are also responsible for the disinfection, processing, testing, storage, distribution, and use of breast milk. As DHM is a biological product, it may get contaminated. Microbiological testing is the final step to determine microbial contamination of DHM. However, a universal method for the microbiological analysis of DHM in breast milk banks globally is lacking.DHM without strict screening may become a potential carrier of pathogens and seriously threaten the health of infants. Clostridium perfringens, a gram-positive anaerobic bacterium, is capable of causing wound infections, including gas gangrene, enteritis/enterocolitis, and enterotoxemia. Here, the first case of C. perfringens detected in DHM has been reported to facilitate the identification of such contamination in breast milk banks.Case presentationA breastfeeding mother donated 3000 mL of milk to the breast milk bank of the First Affiliated Hospital of the Army Medical University(over 2900 beds and patient receiving capacity of over 132,000), Chongqing, China. The milk sample was subjected to microbiological screening using liquid enrichment, followed by anaerobic and aerobic culturing. The results revealed the growth of C. perfringens in the anaerobic culture medium, but no bacteria or yeast-like fungi were observed in the aerobic culture medium. The donor did not exhibit any clinical symptoms, and her routine blood results and body temperature were normal. However, the infant fed with her milk had recurrent bloody stools. Breast milk bank infection control emergency handling as well as environmental sampling and investigation revealed that the cause was contamination of the donor’s home-use breast pump with C. perfringens. The infant no longer experienced bloody stool once the donor changed the breast pump.ConclusionsC. perfringens can enter breast milk from contaminated pumping environments or devices, thus causing illness in infants. The microbiological testing of DHM in breast milk banks can be accomplished using liquid enrichment, along with anaerobic and aerobic culture, which is of immense significance in improving the standards for microbiological screening, DHM safety, and infant health.

Environmental sampling for typhoidal Salmonellas in household and surface waters in Nepal identifies potential transmission pathways.

Salmonella Typhi and Salmonella Paratyphi, fecal-oral transmitted bacterium, have temporally and geographically heterogeneous pathways of transmission. Previous work in Kathmandu, Nepal implicated stone waterspouts as a dominant transmission pathway after 77% of samples tested positive for Salmonella Typhi and 70% for Salmonella Paratyphi. Due to a falling water table, these spouts no longer provide drinking water, but typhoid fever persists, and the question of the disease's dominant pathway of transmission remains unanswered. We used environmental surveillance to detect Salmonella Typhi and Salmonella Paratyphi A DNA from potential sources of transmission. We collected 370, 1L drinking water samples from a population-based random sample of households in the Kathmandu and Kavre Districts of Nepal between February and October 2019. Between November 2019 and July 2021, we collected 380, 50mL river water samples from 19 sentinel sites on a monthly interval along the rivers leading through the Kathmandu and Kavre Districts. We processed drinking water samples using a single qPCR and processed river water samples using differential centrifugation and qPCR at 0 and after 16 hours of liquid culture enrichment. A 3-cycle threshold (Ct) decrease of Salmonella Typhi or Salmonella Paratyphi, pre- and post-enrichment, was used as evidence of growth. We also performed structured observations of human-environment interactions to understand pathways of potential exposure. Among 370 drinking water samples, Salmonella Typhi was detected in 7 samples (1.8%) and Salmonella Paratyphi A was detected in 4 (1.0%) samples. Among 380 river water samples, Salmonella Typhi was detected in 171 (45%) and Salmonella Paratyphi A was detected in 152 (42%) samples. Samples located upstream of the Kathmandu city center were positive for Salmonella Typhi 12% of the time while samples from locations in and downstream were positive 58% and 67% of the time respectively. Individuals were observed bathing, washing clothes, and washing vegetables in the rivers. These results suggest that drinking water was not the dominant pathway of transmission of Salmonella Typhi and Salmonella Paratyphi A in the Kathmandu Valley in 2019. The high degree of river water contamination and its use for washing vegetables raises the possibility that river systems represent an important source of typhoid exposure in Kathmandu.

Culturable Diversity of Lichen-Associated Yeasts through Enrichment Strategies

Lichens are symbiotic partnerships between a filamentous fungus and a photosymbiotic “alga”. Studies show that lichens harbor endothallic fungi, but that some taxa have been difficult to isolate from the main filamentous thallus-forming fungus and other faster growing lichenicolous/endothallic fungi. Therefore, we aimed to develop and evaluate liquid yeast-enrichment strategies to (1) isolate lichen-associated yeasts in pure culture, and (2) determine the taxonomic placement and breadth of the diversity of culturable yeasts. Eighty-two lichen samples were collected and washed with distilled water, and healthy thalli were ground up and added to seven different yeast-enrichment broths. Yeast colonies were isolated in pure culture and identified using molecular techniques. Initial isolates were identified using BLASTn analysis, and a taxonomic refinement was completed using PhyML analysis. In total, 215 isolates were obtained. The most prevalently isolated ascomycetous yeasts were within the Dothideomycetes (Aureobasidium, Plowrightia, and Dothiora), while the most frequently isolated basidiomycetous yeasts belonged to the genera Curvibasidium, Sporobolomyces, and Tremella. The generic placements could not be determined for 17 isolates, and in total 25 novel species were recovered. The results of this research indicate that (1) lichen-associated yeasts are diverse, (2) employing liquid enrichment strategies is effective for isolating many of these, and (3) lichen thalli represent a valuable untapped reservoir of diverse and novel yeast species.

Liquid Plasticine-Based Electrokinetic Enrichment of Proteins.

Protein analysis is an important approach for disease diagnosis, in which sample pretreatment is an essential step since protein samples are often complex and many protein biomarkers are of low abundance. Here, given the good openness and light transmission of liquid plasticine (LP), which is a liquid entity formed by SiO2 nanoparticles and encapsulated aqueous solution, we developed a LP-based field-amplified sample stacking (FASS) system for protein enrichment. The system was composed of a LP container, a sample solution and a Tris-HCl solution containing hydroxyethyl cellulose (HEC). The system design, mechanism investigation, optimization of experimental parameters and characterization of LP-FASS performance for protein enrichment were well studied. Under the optimized experimental conditions of 1 % HEC, 100 mm Tris-HCl and 100 V in the LP-FASS system, a 40-80 times enrichment of proteins was obtained in 40 min using bovine hemoglobin (BHb) as the model protein using the constructed LP-FASS system. The simultaneous enrichment of multiple proteins (phycocyanin, BHb and cytochrome C) was also realized using the system. The LP-FASS system can serve as a new platform for protein enrichment which is easy to be combined with online and offline detections.

Rapid antimicrobial susceptibility profiling using impedance spectroscopy

The present antibiotic susceptibility testing (AST) techniques based on bacterial culture, gene amplification and mass spectrometry are highly time consuming, labour intensive or expensive. Impedance spectroscopy is an emerging tool for rapid bacterial analysis as it is label-free, real-time, affordable and high-throughput. The over-reliance of this technique on complex chip designs and cell enrichment strategies has, however, slowed its foray into clinical AST. We demonstrate a label-free approach in which a low conductivity zwitterionic buffer is used for boosting impedance sensitivity in simple interdigitated electrodes (IDEs) allowing rapid AST in just 20 min without any liquid flow, biofunctionalization or cell enrichment steps. The detection principle relies on measuring changes in solution resistance due to antibiotic-induced bacterial cell death or growth. While the death-based approach is faster (20 min), it's restricted to surface-acting bactericidal antibiotics. The cell growth approach is longer (60–80 min) but more versatile as it applies to all drug types. Results for antibiotic sensitivity analysis and minimum inhibitory concentration (MIC) determination are illustrated for Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus against a wide class of antibiotics (penicillins, cephalosporins, polymyxins, carbapenems etc.).

Simple and sensitive BIO-PCR detection of potato blackleg pathogens from stem, tuber, and soil samples

A BIO-PCR was developed for the detection of potato blackleg pathogens, including Pectobacterium wasabiae (Pw), P. atrosepticum (Pa), P. carotovorum subsp. brasiliense (Pcb), and Dickeya dianthicola (Ddi). The method was based on the semi-selective incubation of pathogens using pectate-based liquid enrichment medium (LEM) and PCR detection of blackleg pathogens (triplex PCR for Pw, Pa, and Ddi and simplex PCR for Pcb with previously reported primers). Incubation in LEM for 24–120 h at 25 °C was effective in detecting the pathogens from plants (stems and tubers) and the soil around the roots. The detection limit by BIO-PCR from the tuber sample (0.6 g) in 10 ml medium was 2–8 colony-forming units (cfu) for four pathogens, whereas that from soil (10 g) in 100 ml medium was 2 × 102, 3 × 103, 6 × 101, and 2 × 101 cfu for Pw, Pa, Pcb, and Ddi, respectively. All four blackleg pathogens could also be detected from symptomatic stems, progeny tubers, and the soil around the stem base of diseased plants by BIO-PCR. This method is a promising technique for the efficient detection of potato blackleg pathogens not only for seed inspection but also for epidemiological research.

Application of the appropriate molecular biology-based method significantly increases the sensitivity of group B streptococcus detection results

Streptococcus agalactiae (group B streptococcus: GBS) is a leading cause of early- and late-onset diseases in neonates. Reliable results of GBS carriage investigation among pregnant women may decrease the incidence of neonatal infection and mortality. To compare the results of conventional culture investigation with those of the US Food and Drug Administration-approved nucleic acid amplification test (BD Max GBS (Becton Dickinson)), and to establish our own protocols of standard polymerase chain reaction (PCR). A total of 250 vaginal-rectal swabs from three different hospitals in Bydgoszcz, Poland, were used to evaluate GBS carriage. Standard laboratory technique (overnight culture in broth enrichment media) results were compared with those of BD Max GBS assay (Becton Dickinson) and two standard PCR protocols, established to detect the cfb and 16S rRNA S.agalactiae genes, from the overnight cultures of the samples in the liquid enrichment media. The overall GBS carriage was estimated as 16.4-23.2%, depending on the applied detection method. The highest percentage of positive results, from each lab-oratory was obtained with the application of BD Max GBS assay. The differences in the number of positive results obtained with this particular method were statistically significant. Overall, 27 discrepancies were noted for the results obtained with the application of the methods compared. The methods applied for GBS detection differ in sensitivity. A culture technique, though very specific, appears to be less sensitive at detecting S.agalactiae compared with the commercially available BD Max GBS assay or in-house PCR protocols established for this purpose.

Molecular Characterization of Chlorpyrifos Degrading Bacteria Isolated from Contaminated Dairy Farm Soils in Nakuru County, Kenya

Chlorpyrifos [O, O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphonothioate] is an organophosphate widely used as an insecticide against a broad spectrum of pests, including as an acaricide against ticks and mites. Due to environmental persistence and toxicity, it should be eliminated quickly from contaminated sites through biodegradation. Microbial bioremediation is one of the most viable ways of removing Chlorpyrifos (CP) from the environment. However, few studies have been conducted on the bacterial diversity that degrades Chlorpyrifos. The enrichment culture technique conducted in this study isolated chlorpyrifos degrading bacteria in soils from dairy farms in Nakuru County, Kenya. The growth response of the bacteria and degradation of Chlorpyrifos was monitored every five days using UV-VIS Spectrophotometer (600nm). Sequential soil and liquid culture enrichments led to the isolation of eighteen (MA1-MA18) bacterial chlorpyrifos degraders with DNA sequences homologous to members of the genera Pseudomonas, Stenotrophomonas, Bacillus, Alicaligenes, and Achromobacter. The efficacy of four (4) strains was further investigated using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The results showed that all four strains significantly degraded Chlorpyrifos in Minimum Salt Medium (MSM), Lysinibacillus sp.HBUM206408 (79.52%), Stenotrophomonas maltophilia (71.43%), Pseudomonas putida (73.32%), and Achromobacter insuavis (71.03%), producing 2-Hydroxy-3,5,6-trichloropyridine (TCP) as a metabolite in MSM as the only source of carbon. Therefore, these strains can be used for the bioremediation of Chlorpyrifos in contaminated soil. There is a need for further studies to determine the possible mechanisms and other metabolites of Chlorpyrifos degradation by the isolates obtained in the study. Besides, future studies should explore the efficacy and survival of the organisms in the contaminated environment.

Rapid direct detection of pathogens for diagnosis of joint infections by MALDI-TOF MS after liquid enrichment in the BacT/Alert blood culture system.

Pathogen identification is a critical step during diagnosis of infectious diseases. Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight mass spectrometry (MALDI-TOF-MS) has become the gold standard for identification of microorganisms cultured on solid media in microbiology laboratories. Direct identification of microbes from liquid specimen, circumventing the need for the additional overnight cultivation step, has been successfully established for blood culture, urine and liquor. Here, we evaluate the ability of MALDI-TOF MS for direct identification of pathogens in synovial fluid after liquid enrichment in BacT/Alert blood culture bottles. Influence of synovial specimen quality on direct species identification with the MALDI BioTyper/Sepsityper was tested with samples inoculated from pretested native synovia with concomitant inoculation of blood or pus, or highly viscous fluid. Here, we achieved >90% concordance with culture on solid medium, and only mixed-species samples posed significant problems. Performance in routine diagnostics was tested prospectively on bottles inoculated by treating physicians on ward. There, we achieved >70% concordance with culture on solid media. The major contributors to test failure were the absence of a measurable mass signal and mixed-specimen samples. The Sepsityper workflow worked well on samples derived from BacT/Alert blood culture bottles inoculated with synovial fluid, giving concordant results to identification from solid media. Host remnant material in the inoculum, such as blood or pus, had no detrimental effect on identification score values of the BioTyper system after processing with the Sepsityper workflow, and neither had the initial viscosity of the synovial sample.

Adsorption–Desorption of La3+, Eu3+, and Y3+ by Mg(OH)2-Pretreated TP207 Resin

The adsorption–desorption behavior of La3+, Eu3+, and Y3+ by Mg(OH)2-pretreated TP207 resin in sulfate solution has been investigated. The effects of the reaction duration, pH value, flow rate, and adsorption mechanism were studied in detail. The results show that the highest adsorption capacity is obtained at solution pH of 4.0. The adsorption affinity of the resin for the different rare-earth ions lies in the order La3+ > Eu3+ > Y3+, while the static equilibrium adsorption capacity is 0.73 mmol g−1, 0.51 mmol g−1, and 0.35 mmol g−1, respectively. The optimum desorption conditions are 1 mol L−1 hydrochloric acid at a flow rate of 4 mL min−1. The desorption liquid enrichment peaks follow the order La3+ > Eu3+ > Y3+, with corresponding enrichment factors of 24, 23, and 20. The adsorption process of TP207 resin is chemisorption, and the coordination mode between Y3+ and resin functional groups is dominated by three donor atoms, but two for La3+ and Eu3+.

Reducing time in detection of Listeria monocytogenes from food by MALDI-TOF mass spectrometry.

In this study, direct detection of L. monocytogenes from liquid culture and enrichment broths containing foods was investigated by using MALDI-TOF MS. For determining the sole effect of food constituents on detection and accuracy of identification in enrichment broths, sterile foods were used before the experiments with food. L. monocytogenes could be detected in BHI broth after 24h of incubation. Detection period was determined as 18h for 3 × 101cfu/mL initial bacterial count in BHI broth containing sterile food. The period extended in ONE broth containing sterile garnish, which was 24 and 30h for 3 × 101 and 1cfu/mL inoculum, respectively. It was found that identification times in UHT milk were longer than that of canned garnish. In the experiments performed with foods having a specific microbiota; White cheese, iceberg lettuce, parsley and watermelon were used. Although no reliable identification was obtained by using White cheese, iceberg lettuce and parsley, L. monocytogenes could be detected in 24h in the enrichment broth containing watermelon. Detection was achieved during a single step enrichment in a reduced time of 24h for even 1cfu/mL initial inoculum.

Mathematical modeling and simulation of newly isolated bacillus cereus M1GT for tannase production through semi-solid state fermentation with agriculture residue triphala

In this present research, tannase producing bacteria were isolated from the samples of the gastrointestinal tract of a Goat. The liquid enrichment and spread plate technique were adopted and 6 distinct bacterial colonies were isolated on a nutrient agar plate. Based on qualitative and quantitative methods of screening, one isolate among six was found promising and identified as Bacillus cereus M1GT by using 16S rRNA gene sequencing technique. The cost-effective substrate Triphala was used as a tannin and energy source for tannase production through solid-state fermentation in shake flask independently. Process factors were screened by a two-step optimization process i.e. one factor at a time method and central composite design. The study of statistical experimental design with Triphala at optimized conditions showed 6.1-fold (0.116 U/gds) higher in tannase activity than that obtained in submerged fermentation. Further, the kinetics of Bacillus cereus M1GT under optimum process conditions were studied. The Logistic equation (growth, ‘µ’), Luedeking Piret equation (Tannase, ‘α’, and ‘β’) and Substrate utilization equation (Tannic acid, ‘m’ and ‘n’) of unstructured kinetic models were evaluated with the MATLAB program. The experimental and simulated values exhibited a good correspondence, indicating that models will define tannase production process.

An integrated system of air sampling and simultaneous enrichment for rapid biosensing of airborne coronavirus and influenza virus

Point-of-care risk assessment (PCRA) for airborne viruses requires a system that can enrich low-concentration airborne viruses dispersed in field environments into a small volume of liquid. In this study, airborne virus particles were collected to a degree above the limit of detection (LOD) for a real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). This study employed an electrostatic air sampler to capture aerosolized test viruses (human coronavirus 229E (HCoV-229E), influenza A virus subtype H1N1 (A/H1N1), and influenza A virus subtype H3N2 (A/H3N2)) in a continuously flowing liquid (aerosol-to-hydrosol (ATH) enrichment) and a concanavalin A (ConA)-coated magnetic particles (CMPs)-installed fluidic channel for simultaneous hydrosol-to-hydrosol (HTH) enrichment. The air sampler's ATH enrichment capacity (EC) was evaluated using the aerosol counting method. In contrast, the HTH EC for the ATH-collected sample was evaluated using transmission-electron-microscopy (TEM)-based image analysis and real-time qRT-PCR assay. For example, the ATH EC for HCoV-229E was up to 67,000, resulting in a viral concentration of 0.08 PFU/mL (in a liquid sample) for a viral epidemic scenario of 1.2 PFU/m3 (in air). The real-time qRT-PCR assay result for this liquid sample was “non-detectable” however, subsequent HTH enrichment for 10 min caused the “non-detectable” sample to become “detectable” (cycle threshold (CT) value of 33.8 ± 0.06).

Aerosol-to-Hydrosol Sampling and Simultaneous Enrichment of Airborne Bacteria For Rapid Biosensing.

Rapid monitoring of biological particulate matter (Bio-PM, bioaerosols) requires an enrichment technique for concentrating the Bio-PM dispersed in the air into a small volume of liquid. In this study, an electrostatic air sampler is employed to capture aerosolized test bacteria in a carrier liquid (aerosol-to-hydrosol (ATH) enrichment). Simultaneously, the captured bacteria are carried into a fluid channel for hydrosol-to-hydrosol (HTH) enrichment with Concanavalin A coated magnetic particles (CMPs). The ATH enrichment capacity of the air sampler was evaluated with an aerosol particle counter for the following test bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Acinetobacter baumannii. Then, the HTH enrichment capacity for the ATH-collected sample was evaluated using the colony-counting method, scanning electron microscopy based image analysis, fluorescence microscopy, electrical current measurements, and real-time quantitative polymerase chain reaction (qPCR). The ATH and HTH enrichment capacities for the given operation conditions were up to 80 000 and 14.9, respectively, resulting in a total enrichment capacity of up to 1.192 × 106. Given that air-to-liquid enrichment required to prepare detectable bacterial samples for real-time qPCR in field environments is of the order of at least 106, our method can be used to prepare a detectable sample from low-concentration airborne bacteria in the field and significantly reduce the time required for Bio-PM monitoring because of its enrichment capacity.

Programmable Liquid Adhesion on Bio-Inspired Re-Entrant Structures.

Surfaces combining antispreading and high adhesion can find wide applications in the manipulation of liquid droplets, generation of micropatterns and liquid enrichment. To fabricate such surfaces, almost all the traditional methods demand multi-step processes and chemical modification. And even so, most of them cannot be applied for some liquids with extremely low surface energy. In the past decade, multiply re-entrant structures have aroused much attention because of their universal and modification-independent antiadhesion or antipenetration ability. Unfortunately, theories and applications about their liquid adhesion behavior are still rare. In this work, inspired by the springtail skin and gecko feet in the adhered state, it is demonstrated that programmable liquid adhesion is realized on the 3D-printed micro doubly re-entrant arrays. By arranging the arrays reasonably, three different Cassie adhesion behaviors can be obtained: I) no residue adhesion, II) tunable adhesion, and III) absolute adhesion. Furthermore, various arrays are designed to tune macro/micro liquid droplet manipulation, which can find applications in the transportation of liquid droplets, liquid enrichment, generation of tiny droplets, and micropatterns.

Source Community and Assembly Processes Affect the Efficiency of Microbial Microcystin Degradation on Drinking Water Filtration Membranes.

Microbial biofilms in gravity-driven membrane (GDM) filtration systems can efficiently degrade the cyanotoxin microcystin (MC), but it is unclear if this function depends on the presence of MC-producing cyanobacteria in the source water habitat. We assessed the removal of MC from added Microcystis aeruginosa biomass in GDMs fed with water from a lake with regular blooms of toxic cyanobacteria (ExpL) or from a stream without such background (ExpS). While initial MC removal was exclusively due to abiotic processes, significantly higher biological MC removal was observed in ExpL. By contrast, there was no difference in MC degradation capacity between lake and stream bacteria in separately conducted liquid enrichments on pure MC. Co-occurrence network analysis revealed a pronounced modularity of the biofilm communities, with a clear hierarchic distinction according to feed water origin and treatment type. Genotypes in the network modules associated with ExpS had significantly more links to each other, indicating that these biofilms had assembled from a more coherent source community. In turn, signals for stochastic community assembly were stronger in ExpL biofilms. We propose that the less “tightly knit” ExpL biofilm assemblages allowed for the better establishment of facultatively MC degrading bacteria, and thus for higher overall functional efficiency.