Microbial Filtrates Research Articles

Hadal water sampling by in situ microbial filtration and fixation (ISMIFF) apparatus

The deepest point of the oceans is over 10 km depth and is characterized with extremely high hydrostatic pressure. Water sampling from the hadal zone for microbiological studies is therefore difficult. In this study, we demonstrate the application of an in situ microbial filtration and fixation (ISMIFF) apparatus in sampling work from the Challenger Deep. A total of 2300 L hadal waters were filtered by the ISMIFF equipped on a hadal lander during seven deployments. The microbial communities in the hadal samples (>6000 m) collected by the ISMIFF were composed of more heterotrophic Marinimicrobia and less photoautotrophic Prochlorococcus and SAR11 bacteria, compared with those by Niskin bottles. Such a difference in the community structure was not observed in the samples collected by the two methods from ~5000-m depth, indicating an effect of greater depths on sample quality. Our results indicate that the ISMIFF or similar filtration apparatuses are indispensable for hadal water sampling since using Niskin bottles is probably difficult to obtain pristine samples from the hadal zone. Application of the ISMIFF will pave the way to meta-omics studies on the hadal microbes.

Automated Time Series Measurement of Microbial Concentrations in Groundwater-Derived Water Supplies.

Fecal contamination by human and animal pathogens, including viruses, bacteria, and protozoa, is a potential human health hazard, especially with regards to drinking water. Pathogen occurrence in groundwater varies considerably in space and time, which can be difficult to characterize as sampling typically requires hundreds of liters of water to be passed through a filter. Here we describe the design and deployment of an automated sampler suited for hydrogeologically and chemically dynamic groundwater systems. Our design focused on a compact form to facilitate transport and quick deployment to municipal and domestic water supplies. We deployed a sampler to characterize water quality from a household well tapping a shallow fractured dolomite aquifer in northeast Wisconsin. The sampler was deployed from January to April 2017, and monitored temperature, nitrate, chloride, specific conductance, and fluorescent dissolved organic matter on a minute time step; water was directed to sequential microbial filters during three recharge periods that ranged from 5 to 20 days. Results from the automated sampler demonstrate the dynamic nature of the household water quality, especially with regard to microbial targets, which were shown to vary 1 to 2 orders of magnitude during a single sampling event. We believe assessments of pathogen occurrence and concentration, and related assessments of drinking well vulnerability, would be improved by the time‐integrated characterization provided by this sampler.

Household Production of Ceramic Water Filters in Western Rajasthan, India

Frustum shaped clay ceramic water filters are being manufactured by the potters of the Thar Desert in India for household use. The clay composite consists of a homogeneous mixture of equal volume of clay and sawdust. A low-cost manual press, to form the clay composite into frustum shape, is developed by the present authors. This article elaborates critical investigation of the specific traditional clay-firing technique used, to achieve the required functionality and material property of the filters. Household based manufacturing of these filters is found to be markedly different from factory based production by firing process. The functional features of the clay ceramic filter, such as microbial filtration rate, flow rate, and compressive strength, are evaluated and presented. An E. coli bacteria removal efficiency of more than 99% is achieved using these clay ceramic water filters. Optimal filtration rates are achieved between ambient temperatures ranging from 30oC - 40oC.

Host-specific effects of soil microbial filtrates prevail over those of arbuscular mycorrhizae in a fragmented landscape.

Plant-soil interactions have been shown to determine plant community composition in a wide range of environments. However, how plants distinctly interact with beneficial and detrimental organisms across mosaic landscapes containing fragmented habitats is still poorly understood. We experimentally tested feedback responses between plants and soil microbial communities from adjacent habitats across a disturbance gradient within a human-modified tropical montane landscape. In a greenhouse experiment, two components of soil microbial communities were amplified; arbuscular mycorrhizal fungi (AMF) and a filtrate excluding AMF spores from the soils of pastures (high disturbance), coffee plantations (intermediate disturbance), and forest fragments (low disturbance), using potted seedlings of 11 plant species common in these habitats (pasture grass, coffee, and nine native species). We then examined their effects on growth of these same 11 host species with reciprocal habitat inoculation. Most plant species received a similar benefit from AMF, but differed in their response to the filtrates from the three habitats. Soil filtrate from pastures had a net negative effect on plant growth, while filtrates from coffee plantations and forests had a net positive effect on plant growth. Pasture grass, coffee, and five pioneer tree species performed better with the filtrate from "away" (where these species rarely occur) compared to "home" (where these species typically occur) habitat soils, while four shade-tolerant tree species grew similarly with filtrates from different habitats. These results suggest that pastures accumulate species-specific soil enemies, while coffee plantations and forests accumulate beneficial soil microbes that benefit pioneer native plants and coffee, respectively. Thus, compared to AMF, soil filtrates exerted stronger habitat and host-specific effects on plants, being more important mediators of plant-soil feedbacks across contrasting habitats.

Isolation and characterization of seven quorum quenching bacteria for biofouling control in MBR

Recently, interspecies quorum quenching (QQ) by bacteria has been reported as a novel approach in biofouling control in membrane bioreactor (MBR) for wastewater treatment. In this study, seven QQ bacteria, named RO1 to RO7, were isolated from fouling reverse osmosis (RO) membrane and were encapsulated in the microbial filters for biofouling control in MBR. Results showed that all isolates have extracellular QQ activity, and RO1 to RO6 were characterized as heat-stable enzymatic degradation of N-acyl homoserine lactones (AHLs), while RO7 was mainly pH-dependent. Analysis of the 16S rRNA gene indicated that RO7 was a species of Pseudomonas sp., others belonged to the species of Bacillus, Stenotrophomonas maltophilia and Delftia tsuruhatensis, respectively. Then, the microbial filters encapsulated each isolate were applied in a laboratory-scaled MBR and proved the substantial inhibition effect on membrane biofouling except for RO7, indicating that QQ bacteria employing enzymes to degrade AHLs have great potential in biofouling control in MBR.

Arbuscular mycorrhizal fungal hyphae reduce soil erosion by surface water flow in a greenhouse experiment

The role of arbuscular mycorrhizal fungi (AMF) in resisting surface flow soil erosion has never been tested experimentally. We set up a full factorial greenhouse experiment using Achillea millefolium with treatments consisting of addition of AMF inoculum and non-microbial filtrate, non-AMF inoculum and microbial filtrate, AMF inoculum and microbial filtrate, and non-AMF inoculum and non-microbial filtrate (control) which were subjected to a constant shear stress in the form of surface water flow to quantify the soil detachment rate through time. We found that soil loss can be explained by the combined effect of roots and AMF extraradical hyphae and we could disentangle the unique effect of AMF hyphal length, which significantly reduced soil loss, highlighting their potential importance in riparian systems.

Biocidal Nano-Silver Reinforced Activated Charcoal in Water Treatment

Improvements in nanotechnology make eco-friendly and cost-effective solutions to the drinking water contamination problem feasible. Activated charcoal, which is widely used for water purification, can be more effectively employed when reinforced with nanoparticles. For antimicrobial water treatment activated charcoal can be reinforced with silver nanoparticles (SNPs) for best results. Among various methods for the synthesis of nanoparticles, green synthesis mediated by phytoconstituents is preferable, as it is both cost-effective and environmentally friendly. Here we report a green method for synthesizing SNPs from musk melon fruit extract and activated charcoal from coconut shells. The prepared activated charcoal was reinforced with the green-synthesized SNPs and used in microbial water filtration. The efficiency of nanosilver reinforced activated charcoal was higher than virgin activated charcoal proving improved filtration against microbes after successful reinforcement.

Biological treatment of 2,4,6-trinitrotoluene (TNT) red water by immobilized anaerobic–aerobic microbial filters

Abstract An immobilized microbial process containing anaerobic filters and biological aerated filters (I-AF-BAF) system was used to treat 2,4,6-trinitrotoluene (TNT) red water. The results showed that the system could effectively degrade the organic pollutants in TNT red water, especially 2,4-dinitrotoluene-5-sulfonate (2,4-DNT-5-SO 3 − ), most of which was degraded by the microorganisms in the system. The results of high performance liquid chromatographic (HPLC) and liquid chromatography–mass spectrum (LC–MS) indicated that 2-amino-4-mononitrotoluene(MNT)-5-SO 3 − and 3-amino-2-MNT-5-SO 3 − might be the main anaerobic degradation metabolites. As the extra carbon source and electron donor, ethanol played a major role in the biodegradation of TNT red water. In addition, environment scanning electron microscope (ESEM) analysis revealed that many globular microorganisms were successfully immobilized on the surface of the carriers. Further analysis by polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) demonstrated that some special bacteria for the degradation of the pollutants in TNT red water might be generated during the acclimatization with TNT red water for 110 days, and they were identified as Hydrogenophaga sp., Exiguobacterium sp., Azospirillum zeae , Rhizobium sp., and iron-reducing bacterium by comparing the gene sequences from Genbank. This study may be useful for the treatment of actual TNT red water loaded with high concentrations of salinity and toxic organic components.

Preparation and properties of hydroxyapatite/titania composite for microbial filtration application

A series of TiO2 modified hydroxyapatite composites (HA/TiO2) with different compositions were prepared. Phase formations and morphologies of the obtained HA/TiO2 composite were characterised using X-ray diffraction and SEM, and their photocatalytic activities were also determined by decomposition of methylene blue solution. Filter cloths were prepared by depositing the composite on polyester non-wovens via pad dry cure, and their filtering effectiveness was examined by photocatalytic activity measurement and bactericidal test. Hydroxyapatite/TiO2 composites were successfully prepared and exhibited photocatalytic properties. With increasing ratio of anatase titania in the HA/TiO2 composite from 20 to 30 and 50%, photocatalytic activity of composite material increased such that HATi5050 composite exhibited the highest photocatalytic activity. Non-woven filters coated with HA/TiO2 composites also exhibited good photocatalytic activities. Less difference in photocatalytic activity between HATi7030 and HATi5050 coated non-woven filters was observed, compared to that in powder form. The filter coated with HA/TiO2 composite exhibited good bactericidal effect.

A novel electrospun polyurethane nanofibre membrane – production parameters and suitability for wastewater (WW) treatment

The aim of this study was to investigate the suitability of a novel electrospun polyurethane nanofibre material for water-treatment purposes. Bacterial removal efficiency was tested in the laboratory by filtering artificial water spiked with Escherichia coli through a 0.25 µm nanofibre membrane. The results were compared with those obtained using a commercial microfiltration material (MV020T) with a similar pore size (0.20 µm). Alongside the laboratory experiments, we also determined filtration efficiency with semi-pilot scale experiments using actual wastewater from the secondary sedimentation tank of a wastewater treatment plant. The laboratory experiments indicated very high log10 removal efficiency, ranging from 5.8 to 6.8 CFU (colony-forming units)/ml. These results were better than those of the commercial membrane (3.8-4.6 CFU/ml). The semi-pilot scale experiment confirmed the membrane's suitability for microbial filtration, with both E. coli and total culturable microorganisms (cultured at both 22 and 36 °C) showing a significant decline compared to the non-filtered control (wastewater from the secondary outlet).

Green synthesis of biocidal silver-activated charcoal nanocomposite for disinfecting water

We report for the first time the green synthesis of silver nanoparticles using West Indian cherry (Malpighia emarginata) extract known for its high vitamin C content. UV–visible spectroscopy, powder X ray diffraction (PXRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy dispersive X ray spectroscopy (EDX) analysis were used to characterise silver nanoparticles. Silver nanoparticles thus synthesised exhibit antimicrobial activity against gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, and gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus. The antimicrobial property of nanoparticles thus synthesised was applied in the production of silver-activated charcoal nanocomposite towards fabrication of antimicrobial water filtration columns. The microbial filtration efficiency of the nanocomposite was found to be higher compared to virgin activated charcoal even with reusage.

Eco-Friendly Biocidal Silver-Activated Charcoal Nanocomposite: Antimicrobial Application in Water Purification

The authors report an eco-friendly way of synthesizing silver nanoparticles (SNPs) using tomato fruit extract and its characterization using XRD, SEM, particle size analyzer, and UV-Visible spectroscopy. The SNPs were used along with activated charcoal as nanocomposite for water purification and the efficiency of the nanocomposite in microbial filtration was evaluated. The nanocomposite was found to be effective against water contaminating microbes. The nanocomposite exhibited very good water purification and reuse efficiency compared to virgin activated charcoal.

Responses of nematode‐community structure in turfgrass soil to microbial filtrates from municipal–solid waste compost

AbstractActinomycetes,Bacillus subtilis,andBacillus thuringiensiswere isolated from municipal–solid waste (MSW) compost, and different microbial liquid filtrates (MLF) were prepared. Sterile culture media with no microbes were used as their controls. The effects of MLF on soil nematode communities were examined in pot‐grownFestuca arundinaceaSchreb. Fifteen genera of nematodes in background soil were identified, of whichHelicotylenchusandRotylenchuswere dominant. The inoculation of MLF strongly affected the abundance and community structure of soil nematodes. Compared with their controls, lower total nematode numbers following MLF incorporation were found. Actinomycetes inoculation changed community structure of soil nematodes, transforming the dominant genera fromHelicotylenchusandRotylenchusintoCephalobus, Chiloplacus, andAphelenchus.Actinomycetes incorporation resulted in a significant decrease of plant‐parasitic nematodes relative to control pots. Only plant‐parasitic and omnivorous‐predatory nematodes were found in treatments followingB. subtilisinoculation, andHelicotylenchus, Rotylenchuswere dominant genera with relative abundance of 76.2% and 14.3%, respectively. Although the dominant genera were stillHelicotylenchusandRotylenchus, B. thuringiensisinoculation led to a marked decrease in populations of plant‐parasitic nematodes and an increase in populations of fungivorous and bacterivorous nematodes relative to control. Shannon's diversity index (H′), evenness index (J′), richness index (SR), and Wasilewska index (WI) in pots treated with actinomycetes andB. thuringiensisfiltrates were significantly higher than those of their controls, whereas significant lower dominance index (λ) in actinomycetes andB. thuringiensistreatments was observed than their controls. Plant growth was improved in the treatments inoculated with three microbes. The findings highlight that actinomycetes can most effectively suppress plant‐parasitic nematodes, increase community diversity, evenness, and richness, thus improving soil environment for turf growth.

Detection and quantification of a mycorrhization helper bacterium and a mycorrhizal fungus in plant-soil microcosms at different levels of complexity.

BackgroundHost plant roots, mycorrhizal mycelium and microbes are important and potentially interacting factors shaping the performance of mycorrhization helper bacteria (MHB). We investigated the impact of a soil microbial community on the interaction between the extraradical mycelium of the ectomycorrhizal fungus Piloderma croceum and the MHB Streptomyces sp. AcH 505 in both the presence and the absence of pedunculate oak microcuttings.ResultsSpecific primers were designed to target the internal transcribed spacer of the rDNA and an intergenic region between two protein encoding genes of P. croceum and the intergenic region between the gyrA and gyrB genes of AcH 505. These primers were used to perform real-time PCR with DNA extracted from soil samples. With a sensitivity of 10 genome copies and a linear range of 6 orders of magnitude, these real-time PCR assays enabled the quantification of purified DNA from P. croceum and AcH 505, respectively. In soil microcosms, the fungal PCR signal was not affected by AcH 505 in the absence of the host plant. However, the fungal signal became weaker in the presence of the plant. This decrease was only observed in microbial filtrate amended microcosms. In contrast, the PCR signal of AcH 505 increased in the presence of P. croceum. The increase was not significant in sterile microcosms that contained plant roots.ConclusionsReal-time quantitative PCR assays provide a method for directly detecting and quantifying MHB and mycorrhizal fungi in plant microcosms. Our study indicates that the presence of microorganisms and plant roots can both affect the nature of MHB-fungus interactions, and that mycorrhizal fungi may enhance MHB growth.

Biomedical and pharmacological potential of tetrodotoxin-producing bacteria isolated from marine pufferfish Arothron hispidus (Muller, 1841)

Specimens of the pufferfish Arothron hispidus collected at Parangipettai, on the southeast coast of India, were subjected to bacterial isolation and identification. Three species were identified, namely Bacillus sp., Kytococcus sedentarius and Cellulomonas fimi. Partially-purified microbial filtrates exhibited hemolytic activity on chicken and human erythrocytes of O, B and AB blood groups, with maximum activity of 32 HU. The microbial filtrates also presented ATPase, Mg2+-ATPase, Na+K+-ATPase and AchE enzymatic activities of positive neuromodulation in Kytococcus sedentarius with 1300, 300.1, 1549.98 and 140.55%, in Cellulomonas fimi with 620, 300, 10 and 128.42%, and in Bacillus species with 40, 200, 849.98 and 158.69%, respectively. Toxicity symptoms were observed when the bacterial filtrate was intraperitoneally injected into mice. The bacterial filtrate caused adverse effects on viability of the mouse muscle cell line (L929) and leukemia cell line (P388). Maximum level of inhibition was observed on the growth of L929 cell line. Bacillus lentimorbus inhibited the cell line from 84.03 to 94.43% whereas Bacillus species inhibited the growth in a range between 77.25 and 86.16% at the lowest dilution.

Plant ectoparasitic nematodes prefer roots without their microbial enemies

Root-feeding nematodes are major soil-borne pests in agriculture. In natural ecosystems, their abundance can be strongly controlled by natural enemies. In coastal foredune soil, the abundance of the ectoparasitic nematode Tylenchorhynchus ventralis is controlled by local interactions with soil microorganisms. If not controlled, T. ventralis reduces growth and performance of the host plant Ammophila arenaria. In the present study, we examine if the nematodes may sense the presence of soil microorganisms and, if so, they are able to actively avoid their enemies. First, using Petri dishes with agar medium we examined if T. ventralis can choose between A. arenaria seedlings inoculated with or without soil microorganisms. We observed that there was a trend (although non-significant) in nematode migration towards the non-inoculated plants. If the seedlings were not present, the nematodes did not make any choice and stayed in the centre of the Petri dish. Then, using Y-tubes filled with sterilized dune soil, we examined if T. ventralis could choose between A. arenaria roots with or without microorganisms. We also included treatments of microbial suspensions without plants and a microbe-free filtrate. We observed that the nematodes preferred roots without microorganisms. Microorganisms alone or roots with microbial filtrate did not influence nematode choice significantly. We conclude that the nematode T. ventralis is able to choose roots without soil microorganisms when having roots with them as alternative. Such avoidance could explain why biological control of nematodes in field is not always effective, especially when microbial antagonists accumulate in specific parts of the rhizosphere.

Compatible host/mycorrhizal fungus combinations for micropropagated sea oats: II. Field evaluation

Sea oats (Uniola paniculata L.) are the dominant plant in the pioneer coastal dunes of Florida and are widely used for dune restoration. DNA analysis has revealed significant ecotypic variation among Atlantic and Gulf coast populations of sea oats, but little is known about the diversity of the arbuscular mycorrhizal (AM) communities present in the dune systems. In a prior greenhouse study, we evaluated the functional diversity that exists among the AM fungal communities from divergent Florida dunes and selected effective host/AM fungus combinations for further study. The objective of this study was to evaluate the effect of these compatible combinations on the growth of sea oats planted at Anastasia State Recreation Area (AN) on the Atlantic coast and St. George Island State Park (SG) on the Gulf coast. Micropropagated sea oats from each site were inoculated with AM fungal communities also from AN and SG or a microbial filtrate control. The complete factorial of treatment combinations were grown in the greenhouse for 8 weeks and outplanted to the AN and SG field sites. After 1 year, root colonization was evaluated, and after 2 years, root colonization, shoot and root dry masses, and shoot- and root-P contents were determined. Overall, sea oats planted at AN had greater percent root colonization, shoot dry mass, and shoot-P content than those planted at SG. At AN, the local sea oat ecotype responded more to the fungal community from the same site relative to shoot dry mass and shoot-P content. At SG, the local fungal community produced larger plants with greater P content regardless of the origin of the host. We conclude that sea oat productivity is responsive to AM fungal ecotype as well as host ecotype, and fungal origin should therefore be taken into account when planning sea oat plantings on coastal dunes.

Preparation and properties of hydroxyapatite filters for microbial filtration

Preparation and properties of two kinds of hydroxyapatite filters, filter cloths and porous ceramics, were investigated. The filter cloth was prepared by depositing nanosize ceramic hydroxyapatite on a cotton fabric. The porous ceramic with pore size of several micrometers or less was fabricated by using water soluble starch as a pore former, and its permeability was controlled by adding insoluble starch. Bacterial filtration tests showed that the six-layer filter cloth can clear bacteria effectively, and the porous ceramic can remove 100% of the bacteria. Both the filter cloth and the porous ceramic can be used to clear or separate microbes.

BACTERIOSTATIC BREATHING CIRCUIT FILTRATION DOES NOT EFFECT POST-OPERATIVE WOUND INFECTION RATES IN CARDIAC SURGERY

S138 INTRO: Numerous studies have reported anesthesia machine [1,2] and breathing circuit [2,3] bacterial contamination. Some investigators have suggested the organisms contaminating the anesthesia machines may be partly responsible for post-operative wound infections [3]. High efficiency microbial filters have been found effective in preventing cross contamination from machine to patient and from patient to machine when placed at the Y connector of a standard circle system [3]. This study was designed to determine if breathing circuit bacteriostatic filtration is effective in reducing the incidence of post operative wound infections in patients presenting for elective cardiac surgery. METHODS: Institutional IRB approval was obtained. All adult patients presenting for elective cardiac surgery were randomized to one of two groups. Group FIL had an intertech HEPA filter (Sims Medical Systems, Keene, NH) (filtration efficiency=99.9999+%) placed at the Y Connector of the anesthesia circle system. Group NoF had no filtration or heat/moisture exchange devices. Institutional standards for pre-operative antibiotic treatment and sterile patient preparation were uniform for both patient groups. A power analysis was conducted prior to the start of the study to determine the number of patients necessary to detect a 50% reduction in post-operative wound infections (alpha=0.05, beta=0.2). Statistical significance was determined using Fishers exact test. RESULTS: A total of 259 patients were randomized: 117 patients into group FIL and 142 patients were into group NoF. There were a total of 7 (2.70%)post-operative wound infections: 4 infections (3.42%) in group FIL and 3 infections (2.11%) in group NoF, P=0.62. All were sternal infections, either Staphylococcus epidermidis or Staph. aureus, with equal distribution of pathogens between groups. A post study power analysis was performed to verify sample size selections. Post study power is 0.90. CONCLUSIONS: This study did not demonstrate a reduction in post-operative wound infection rates with the use of bacteriostatic breathing circuit filtration. Although the occurrence of post-operative wound infections is a rare event the sample size and subsequent power analysis of this study allows us to conclude that there is a 90% likelihood that breathing circuit filtration offers no protection against post-operative wound infections. This study was sponsored in part by a grant from Sims Medical Systems, Keene, NH.

Convection warmers--not just hot air.

We sought to determine whether the forced air convection warmers (nine Bair Huggers, Augustine Medical, and one Warm Touch, Mallinkrodt Medical) used in our operating theatres could be a source of microbial pathogens. Agar plates were placed directly in the air stream of the warmers. Four of these grew potentially pathogenic organisms. When the warmers were set to blow through perforated blankets, no growth occurred. Three of the warmers were swabbed and sites of colonisation were found in their hoses. After fixing a microbial filter to the end of the hose, organisms were no longer detectable. We conclude that these warming devices are a potential source of nosocomial infection. They should only be used in conjunction with perforated blankets, should have their microbial filters changed regularly and their hoses sterilised. The inclusion of a microbial filter into the nozzle of the hose could be incorporated into the design of the warmer.