Statistical Copolymers that Mimic Aspects of Mussel Adhesive Proteins: Access to Robust Adhesive-Domains for Non-Covalent Surface PEGylation.

Reconstructing functional sequence motifs of proteins, using statistical copolymers greatly reduces the information content, but simplifies synthesis significantly. Key amino acid residues involved in the adhesion of mussel foot proteins are identified. The side-chain functionalities of Dopa, lysine, and arginine are abstracted and incorporated into acrylate monomers to allow controlled radical polymerization. The resulting Dopa-acrylate (Y*-acr), arginine-acrylate (R-acr), and lysine-acrylate (K-acr) monomers are polymerized in different monomer ratios and compositions by reversible addition fragmentation transfer polymerization with a poly(ethylene glycol) (PEG) macrochain transfer agent. This results in two sets of PEG-block-copolymers with statistical mixtures and different monomer ratios of catechol/primary amine and catechol/guanidine side-chain functionalities, both important pairs for mimicking π-cation interactions. The coating behavior of these PEG-block-copolymers is evaluated using quartz crystal microbalance with dissipation energy monitoring (QCM-D), leading to non-covalent PEGylation of the substrates with clear compositional optima in the coating stability and antifouling properties. The coatings prevent non-reversible albumin or serum adsorption, as well as reduce cellular adhesion and fungal spore attachment.

Inhibitory effect and possible mechanism of phenyllactic acid on Aspergillus flavus spore germination.

Phenyllactic acid (PLA) has gained a lot of attention due to its broad antimicrobial activity, but the mechanism of its antifungal action has been barely reported until now. Herein, the inhibitory activity of PLA against Aspergillus flavus spore germination and its mechanism were preliminarily investigated. Results indicated that PLA had a strong antifungal activity against A. flavus with the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of 6 and 12 mg/ml, respectively. As observed by scanning electron microscopy (SEM), the A. flavus spores displayed wrinkled and shrunken appearance after treatment with PLA. In addition, the permeability and integrity of A. flavus cell membrane were changed obviously after PLA treatment as indicated by the propidium iodide (PI) staining results, which was further confirmed by a rise in electric conductivity and increased leakage of intracellular protein and nucleic acid. Furthermore, reduced activities of mitochondrial ATPase and dehydrogenases caused by PLA were also observed in A. flavus spores, with a result of remarkable decrease in ATP synthesis. Therefore, it could be concluded that PLA was effective in inhibiting spore germination of A. flavus mainly by disrupting cell membrane and interfering with mitochondrial energy metabolism.

Efficacy of novel aqueous photo-chlorine dioxide against a human norovirus surrogate, bacteriophage MS2 and Clostridium difficile endospores, in suspension, on stainless steel and under greenhouse conditions.

AIMS: The efficacy of a novel photochemical method for generating chlorine dioxide (photoClO2 ) was evaluated against human noroviruses (HuNoV) surrogate, bacteriophage MS2, and Clostridium difficile endospores. METHODS AND RESULTS: Chlorine dioxide was generated by mixing 1% sodium chlorite with 10 parts-per-million (ppm) Eosin Y and irradiating with a photo-activator-excitable light. PhotoClO2 efficacy was assessed against bacteriophage MS2 and C. difficile endospores in suspension, on hard surfaces and greenhouse conditions under soiled and unsoiled conditions. The estimated effective photoClO2 produced and consumed was 20·39 ± 0·16 ppm at a rate of 8·16 ppm per min in a 1% sodium chlorite solution. In suspension, MS2 phage was reduced by 3·35 and >5·10 log10 PFU per ml in 120 and 90 min, with and without soil, respectively. At the same time, when dried on stainless steel surface, MS2 phage was reduced by >4·53 log10 PFU per carrier in 30 min under both conditions. On the other hand, C. difficile endospores in suspension were reduced by 2·26 and 3·65 log10 CFU per ml in 120 min with and without soiling, respectively. However, on stainless steel surface, maximal reductions of the C. difficile endospores were 0·8 and 1·5 log10 CFU per carrier with and without soiling, respectively, and a maximal reduction of 2·97 log10 CFU per carrier under greenhouse conditions at 24 h. CONCLUSIONS: Overall, photoClO2 showed promise as a technology to control HuNoV contamination on environmental surfaces but requires further optimization and testing against C. difficile endospores. SIGNIFICANCE AND IMPACT OF THE STUDY: Results from this investigation will serve as a model for how to generate and quantify photoClO2 and how to appropriately evaluate this new class of disinfectants against environmentally resilient pathogens: viruses and bacterial endospores.

Bacillus subtilis spore vaccines displaying protective antigen induce functional antibodies and protective potency.

BACKGROUND: Bacillus anthracis is the causative agent of anthrax, a disease of both humans and various animal species, and can be used as a bioterror agent. Effective vaccines are available, but those could benefit from improvements, including increasing the immunity duration, reducing the shot frequency and adverse reactions. In addition, more sophisticated antigen delivery and potentiation systems are urgently required. The protective antigen (PA), one of three major virulence factors associated with anthrax was displayed on the surface of Bacillus subtilis spores, which is a vaccine production host and delivery vector with several advantages such as a low production cost, straightforward administration as it is safe for human consumption and the particulate adjuvanticity. Mice were immunized orally (PO), intranasally (IN), sublingually (SL) or intraperitoneally (IP) with the PA displaying probiotic spore vaccine. Clinical observation, serological analysis and challenge experiment were conducted to investigate the safety and efficacy of the vaccine. RESULTS: A/J mice immunized with the PA spore vaccine via PO, IN, SL, and IP were observed to have increased levels of active antibody titer, isotype profiles and toxin neutralizing antibody in sera, and IgA in saliva. The immunized mice were demonstrated to raise protective immunity against the challenge with lethal B. anthracis spores. CONCLUSIONS: In this study, we developed a B. subtilis spore vaccine that displays the PA on its surface and showed that the PA-displaying spore vaccine was able to confer active immunity to a murine model based on the results of antibody isotype titration, mucosal antibody identification, and a lethal challenge experiment.

Thin polyester filters as versatile sample substrates for high-pressure freezing of bacterial biofilms, suspended microorganisms and adherent eukaryotic cells.

High-pressure freezing limits the size of biological samples, because only small samples can be frozen without ice damage. Additionally, these samples must fit into the dimensions of the sample holder provided by the high-pressure freezer. We explored the potential of a 10 µm thin polyester filter membrane (PE-filter) as a versatile sample substrate for high-pressure freezing. Planktonic bacteria, bacterial spores and suspended eukaryotic cells could be concentrated on the PE-filter, whereas biofilm, bacterial microcolonies and HeLa cells were able to grow directly on the PE-filter. These microorganism-loaded PE-filters were used for high-pressure freezing, freeze-substitution and plastic embedding in Epon or Lowicryl. Embedded filters were cross-sectioned so that the interface between microorganism and substrate as well as the overlying medium was revealed. Although the structural preservation was good for thin samples and samples with lower water content, such as biofilms, adherent HeLa-cell cultures were likewise sufficiently preserved for transmission electron microscopy imaging. The fact that microorganism-loaded PE-filters could be also examined with confocal laser scanning fluorescence microscopy under fully hydrated conditions, and freeze-substituted PE-filters samples with scanning electron microscopy, demonstrates the versatility of the PE-filter as a sample substrate for a wide array of microorganisms. LAY DESCRIPTION: In order to investigate biological samples in the transmission electron microscope it is imperative to remove all their water content, or the specimens will be destroyed by boiling in the high vacuum of the microscope. In order to avoid dramatic morphology-changes due to drying artefacts or the impact of chemical stabilisers, high-pressure freezing (HPF) was developed. This protocol allows freezing biological samples in an instant (within a few milliseconds) down to -196°C while applying high pressure at the same time so that the specimen retains all its water in a solidified noncrystalline form. However, the formation of morphology-destroying ice crystals is only avoided, if the cooling of the sample is faster than the ice crystal formation, which is only possible with very thin samples (up to a maximum of 200 µm in optimal cases). High-pressure freezing is regarded as the gold-standard for sample preparation of cells, tissues and small organisms. However, all of these samples must fit into the dimensions of the specific sample holder of the high-pressure freezer and their transfer into the high-pressure freezing machine must be achieved without significant impact on sample physiology. Additionally, it may also necessary to concentrate and immobilise a biological specimen before they can be placed in the HPF sample holder. Although a few number of strategies and sample substrates have been used for different types of biological samples, we explored the potential of a 10 µm thin polyester filter membrane (PE-filter) as a versatile sample substrate for HPF. In culture medium suspended bacteria, suspended bacterial spores and in medium suspended higher cells could be concentrated on the PE-filter, whereas bacterial biofilm or bacterial microcolonies from an agar plate, and surface-adhering higher cells were able to grow directly on the PE-filter. These microorganism-loaded PE-filters could be directly used for high-pressure freezing, and were finally embedded in a plastic resin like Epon or Lowicryl. Embedded filters were cross-sectioned so that the interface between microorganism and substrate or overlying medium was revealed. Although the structural preservation was good for thin samples and samples with lower water content, such as biofilms, adherent HeLa-cell cultures were likewise sufficiently preserved for transmission electron microscopy imaging. The fact that microorganism-loaded PE-filters could be also examined with confocal laser scanning fluorescence microscopy under fully hydrated conditions, and freeze-substituted PE-filters samples with scanning-electron microscopy, demonstrates the versatility of the PE-filter as a sample substrate for a wide array of microorganisms.

Antialgal activity of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes against the marine alga Ulva.

Marine biofouling has detrimental effects on the environment and economy, and current antifouling coatings research is aimed at environmentally benign, non-toxic materials. The possibility of using contact-active coatings is explored, by considering the antialgal activity of cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. The antialgal activity was investigated via zoospore settlement and sporeling growth assays of the marine algae Ulva linza and U. lactuca. The assay results for PDMAEMA brushes were compared to those for anionic and neutral surfaces. It was found that only PDMAEMA could disrupt zoospores that come into contact with it, and that it also inhibits the subsequent growth of normally settled spores. Based on the spore membrane properties, and characterization of the PDMAEMA brushes over a wide pH range, it is hypothesized that the algicidal mechanisms are similar to the bactericidal mechanisms of cationic polymers, and that further development could lead to successful contact-active antialgal coatings.

Conservation of Male Sterility 2 function during spore and pollen wall development supports an evolutionarily early recruitment of a core component in the sporopollenin biosynthetic pathway.

The early evolution of plants required the acquisition of a number of key adaptations to overcome physiological difficulties associated with survival on land. One of these was a tough sporopollenin wall that enclosed reproductive propagules and provided protection from desiccation and UV-B radiation. All land plants possess such walled spores (or their derived homologue, pollen). We took a reverse genetics approach, consisting of knock-out and complementation experiments to test the functional conservation of the sporopollenin-associated gene MALE STERILTY 2 (which is essential for pollen wall development in Arabidopsis thaliana) in the bryophyte Physcomitrella patens. Knock-outs of a putative moss homologue of the A. thaliana MS2 gene, which is highly expressed in the moss sporophyte, led to spores with highly defective walls comparable to that observed in the A. thaliana ms2 mutant, and extremely compromised germination. Conversely, the moss MS2 gene could not rescue the A. thaliana ms2 phenotype. The results presented here suggest that a core component of the biochemical and developmental pathway required for angiosperm pollen wall development was recruited early in land plant evolution but the continued increase in pollen wall complexity observed in angiosperms has been accompanied by divergence in MS2 gene function.

A Model for Mechanical Stress Limited Bacterial Growth and Resporulation in Confinement.

In this study, we propose a self-limiting growth model forBacillus subtilisspores confined within porous polyacrylamide (PA) hydrogels. We observed thatB. subtilisspores germinate into vegetative cells within the hydrogel matrix, forming spherical colonies. These colonies expand until the mechanical stress they exert on their environment surpasses the yield stress of the hydrogel, leading to formation of a nonpermeable layer that halts nutrient diffusion and forces the bacteria to resporulate. These novel observations suggest a model to explain why bacterial growth in confined environments and material interfaces may be limited, providing insight for natural phenomena and biotechnological applications involving bacterial encapsulation.

Effect of spo0A, sigE, sigG, and sigK disruption on butanol production and spore formation in Clostridium saccharoperbutylacetonicum strain N1-4 (ATCC13564).

Clostridium saccharoperbutylacetonicum strain N1-4 (ATCC13564) is a butanol-producing strain suitable for application to butanol production from cellulosic materials by co-culture with cellulolytic and thermophilic species, such as Hungateiclostridium thermocellum (synonym: Clostridium thermocellum). The optimal temperature for butanol production by strain N1-4 is 30 °C, and the strain is sensitive to a high culture temperature of 37 °C. Given that spore formation is observed at high frequency when strain N1-4 is cultivated at 37 °C, we assumed in a previous study that the initiation of sporulation is related to a decrease in butanol production. Therefore, to investigate the relationship between butanol production and spore formation, we generated strain N1-4 isolates in which genes related to spore formation were disrupted. The sporulation-related gene disruptants of spo0A, sigE, sigG, and sigK lost the ability to produce heat-resistant spores, irrespective of the culture temperature. Among the gene disruptants produced, only the spo0A disruptant lost butanol-producing ability when cultivated at 30 °C. Interestingly, the sigE disruptant maintained butanol productivity similar to that observed at 30 °C, even when cultivated at 37 °C. In addition, the sigE disruptant successfully produced butanol from Avicel cellulose by co-culture with H. thermocellum at a fermentation temperature of 37 °C.

Synthesis of bioactive microcapsules using a microfluidic device.

Bioactive microcapsules containing Bacillus thuringiensis (BT) spores were generated by a combination of a hydro gel, microfluidic device and chemical polymerization method. As a proof-of-principle, we used BT spores displaying enhanced green fluorescent protein (EGFP) on the spore surface to spatially direct the EGFP-presenting spores within microcapsules. BT spore-encapsulated microdroplets of uniform size and shape are prepared through a flow-focusing method in a microfluidic device and converted into microcapsules through hydrogel polymerization. The size of microdroplets can be controlled by changing both the dispersion and continuous flow rate. Poly(N-isoproplyacrylamide) (PNIPAM), known as a hydrogel material, was employed as a biocompatible material for the encapsulation of BT spores and long-term storage and outstanding stability. Due to these unique properties of PNIPAM, the nutrients from Luria-Bertani complex medium diffused into the microcapsules and the microencapsulated spores germinated into vegetative cells under adequate environmental conditions. These results suggest that there is no limitation of transferring low-molecular-weight-substrates through the PNIPAM structures, and the viability of microencapsulated spores was confirmed by the culture of vegetative cells after the germinations. This microfluidic-based microencapsulation methodology provides a unique way of synthesizing bioactive microcapsules in a one-step process. This microfluidic-based strategy would be potentially suitable to produce microcapsules of various microbial spores for on-site biosensor analysis.

Efficient production of fungal spores by the combination of reduction of nitrogen source content and embedding of hydrophobic polymer in an agar plate.

Fungal sporulation is affected by many environmental factors, for example, we previously observed that embedding of a hydrophobic polymer net in an agar plate medium significantly accelerates spore formation of some fungi. Here, it was found that the fungal spore formation depended on the surface hydrophobicity of cultivation vessels used for the plate cultivation. In a polypropylene (PP) vessel, six fungal strains produced spores of 1.5 to 514.8 times of those growing in a glass vessel. The contact of vegetative hyphae on the surface of the vessels might trigger the fungal spore formation. Moreover, the spore formation was synergistically accelerated by the reduction of nitrogen source content in an agar plate medium and by the contact to hydrophobic polymers. The synergistic effect depended on the surface area of the hydrophobic polymer. Thus, the combination of the reduction of nitrogen source and the embedding of hydrophobic polymer is expected as a novel and effective procedure for production of fungal spores which are useful for the inoculum in fermentation industry and biocontrol agent in agriculture.

Inactivation of Bacillus cereus Spores on Stainless Steel by Combined Superheated Steam and UV-C Irradiation Treatment.

Bacillus cereus spore contamination on food contact surfaces is of great concern in the food industry. Thus, in the present study, superheated steam (SHS) was used alone or combined with UV-C irradiation for inactivation of B. cereus spores inoculated on stainless steel coupons. Temperatures higher than 250°C were needed to effectively inactivate B. cereus spores by SHS treatment alone, while a synergistic bactericidal effect resulted from the sequential treatment of SHS before or after UV-C irradiation. The increased dipicolinic acid ratio obtained by the combined treatment had a significant role in the synergistic bactericidal effect. Therefore, the combined treatment of SHS and UV-C could be used effectively to inactivate B. cereus on stainless steel. It is recommended to use hurdle technology with reduced energy consumption to ensure microbiological safety on food contact surfaces.

Inactivation kinetics of slightly acidic electrolyzed water combined with benzalkonium chloride and mild heat treatment on vegetative cells, spores, and biofilms of Bacillus cereus.

Bacillus cereus can exist as vegetative cells, spores, and biofilms in food-processing environment, posing a big challenge for the food industry. The objective of this study was to examine the inactivation efficacy of slightly acidic electrolyzed water (SAEW) in combination with benzalkonium chloride (BAC) and mild heat treatment (50 and 60 °C) on B. cereus strains (ATCC 10987 and ATCC 14579). The inactivation efficacy of SAEW was found to be largely dependent on available chlorine concentration (ACC) level and exposure time as well as B. cereus strains and growth conditions. SAEW with ACC of 40 ppm reduced ATCC 10987 and ATCC 14579 vegetative cells to the non-detection limit within 30 s. and 1 min, respectively. Combination treatment with SAEW+60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 0.76 logCFU/ml, 0.59 logCFU/ml, and 1.28 logCFU/cm2, respectively. While, treatment with SAEW+BAC + 60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 1.91 logCFU/ml, 1.98 logCFU/ml, and 2.62 logCFU/cm2, respectively. The inactivation kinetics under different ACC of SAEW and in combination with BAC and mild treatment were determined by Weibull model. The calculated adjusted correlation coefficients (R2adj) and root mean sum of squared error (RMSE) values for all curves were found to be ranges from 0.95-0.99 and 0.04-0.23, respectively, indicating that the Weibull model precisely predicted the inactivation kinetics of B. cereus during SAEW in combination with BAC and mild heat treatments. These results suggest that SAEW in combination with BAC and mild heat may be used as an effective cleaning strategy against B. cereus in the food contact surfaces.

Acceleration of fungal spore production by embedding a hydrophobic polymer net in a nutrient agar plate.

A simple and novel procedure for the acceleration of fungal spore production was developed. A net of hydrophobic polymer such as polypropylene (PP) and polytetrafluoroethylene (PTFE) was embedded in a nutrient agar plate, and effect of the polymer net on spore production by 6 fungal strains, such as Aspergillus terreus, Penicillium multicolor, and Trichoderma virens were estimated. The effect of hydrophobic polymer net was insufficient in a liquid-surface immobilization (LSI) system with fungal cells immobilized on a ballooned microsphere layer formed on a liquid medium surface. On the other hand, the embedding of a PTFE net in an agar plate remarkably enhanced the spore production in all 6 strains tested to produce 2.0-8.5 × 107 spores/cm2-agar plate surface. Especially, the spore production by A. terreus ATCC 20542 in the presence of a PTFE net was 7.7 times as much than that in no net. Positive correlations between the hydrophobicity of net and the spore production were observed in all 6 strains (R2, 0.653-0.999).

Inactivation of Clostridium perfringens spores adhered onto stainless steel surface by agents used in a clean-in-place procedure.

Enterotoxigenic Clostridium perfringens, a leading foodborne pathogen can be cross-contaminated from food processing stainless steel (SS) surfaces to the finished food products. This is mostly due to the high resistance of C. perfringens spores adhered onto SS surfaces to various disinfectants commonly used in food industries. In this study, we aimed to investigate the survivability and adherence of C. perfringens spores onto SS surfaces and then validate the effectiveness of a simulated Clean-in-Place (CIP) regime on inactivation of spores adhered onto SS surfaces. Our results demonstrated that, 1) C. perfringens spores adhered firmly onto SS surfaces and survived for at-least 48 h, unlike their vegetative cells who died within 30 min, after aerobic incubation at refrigerated and ambient temperatures; 2) Spores exhibited higher levels of hydrophobicity than vegetative cells, suggesting a correlation between cell surface hydrophobicity and adhesion to solid surfaces; 3) Intact spores were more hydrophobic than the decoated spores, suggesting a positive role of spore coat components on spores' hydrophobicity and thus adhesion onto SS surfaces; and finally 4) The CIP regime (NaOH + HNO3) successfully inactivated C. perfringens spores adhered onto SS surfaces, and most of the effect of CIP regime appeared to be due to the NaOH. Collectively, our current findings may well contribute towards developing a strategy to control cross-contamination of C. perfringens spores into food products, which should help reducing the risk of C. perfringens-associated food poisoning outbreaks.

Spore liberation in mosses revisited.

The ability to perform hygroscopic movements has evolved in many plant lineages and relates to a multitude of different functions such as seed burial, flower protection or regulation of diaspore release. In most mosses, spore release is controlled by hygroscopic movements of the peristome teeth and also of the spore capsule. Our study presents, for the first time, temporally and spatially well-resolved kinematic analyses of these complex shape changes in response to humidity conditions and provides insights into the sophisticated functional morphology and anatomy of the peristome teeth. In Brachythecium populeum the outer teeth of the peristome perform particularly complex hygroscopic movements during hydration and desiccation. Hydration induces fast inward dipping followed by partial re-straightening of the teeth. In their final shape, wet teeth close the capsule. During desiccation, the teeth perform an outward flicking followed by a re-straightening which opens the capsule. We present a kinematic analysis of these shape changes and of the underlying functional anatomy of the teeth. These teeth are shown to be composed of two layers which show longitudinal gradients in their material composition, structure and geometry. We hypothesize that these gradients result in (i) differences in swelling/shrinking capacity and velocity between the two layers composing the teeth, and in (ii) a gradient of velocity of swelling and shrinking from the tip to the base of the teeth. We propose these processes explain the observed movements regulating capsule opening or closing. This hypothesis is corroborated by experiments with isolated layers of peristome teeth. During hydration and desiccation, changes to the shape and mass of the whole spore capsule accompany the opening and closing. Results are discussed in relation to their significance for humidity-based regulation of spore release.

Bacillus amyloliquefaciens Spore Production Under Solid-State Fermentation of Lignocellulosic Residues.

This study was conducted to elucidate cultivation conditions determining Bacillus amyloliquefaciens B-1895 growth and enhanced spore formation during the solid-state fermentation (SSF) of agro-industrial lignocellulosic biomasses. Among the tested growth substrates, corncobs provided the highest yield of spores (47 × 1010 spores g-1 biomass) while the mushroom spent substrate and sunflower oil mill appeared to be poor growth substrates for spore formation. Maximum spore yield (82 × 1010 spores g-1 biomass) was achieved when 15 g corncobs were moistened with 60 ml of the optimized nutrient medium containing 10 g peptone, 2 g KH2PO4, 1 g MgSO4·7H2O, and 1 g NaCl per 1 l of distilled water. The cheese whey usage for wetting of lignocellulosic substrate instead water promoted spore formation and increased the spore number to 105 × 1010 spores g-1. Addition to the cheese whey of optimized medium components favored sporulation process. The feasibility of developed medium and strategy was shown in scaled up SSF of corncobs in polypropylene bags since yield of 10 × 1011 spores per gram of dry biomass was achieved. In the SSF of lignocellulose, B. amyloliquefaciens B-1895 secreted comparatively high cellulase and xylanase activities to ensure good growth of the bacterial culture.

Assessing the Impact of Germination and Sporulation Conditions on the Adhesion of Bacillus Spores to Glass and Stainless Steel by Fluid Dynamic Gauging.

The adhesion of spores of 3 Bacillus species with distinctive morphologies to stainless steel and borosilicate glass was studied using the fluid dynamic gauging technique. Marked differences were observed between different species of spores, and also between spores of the same species prepared under different sporulation conditions. Spores of the food-borne pathogen B. cereus were demonstrated to be capable of withstanding shear stresses greater than 1500 Pa when adhered to stainless steel, in contrast to spores of Bacillus subtilis and Bacillus megaterium, which detached in response to lower shear stress. An extended DLVO model was shown to be capable of predicting the relative differences in spore adhesion between spores of different species and different culture conditions, but did not predict absolute values of force of adhesion well. Applying the model to germinating spores showed a significant reduction in adhesion force shortly after triggering germination, indicating a potential strategy to achieve enhanced removal of spores from surfaces in response to shear stress, such as during cleaning-in-place procedures. PRACTICAL APPLICATION: Spore-forming bacteria are a concern to the food industry because they have the potential to cause food-borne illness and product spoilage, while being strongly adhesive to processing surfaces and resistant to cleaning-in-place procedures. This work is of significance to the food processors and manufacturers because it offers insight to the properties of spore adhesion and identifies a potential strategy to facilitate the removal of spores during cleaning procedures.

Enhancement of sludge dewaterability with filamentous fungi Talaromyces flavus S1 by depletion of extracellular polymeric substances or mycelium entrapment.

This study was conducted to explore the mechanism of dewaterability improvement of waste activated sludge by the filamentous fungus Talaromyces flavus S1. When the fungal spores were inoculated to the sterilized sludge, the sludge dewaterability was significantly improved by 48.1% and the reasons can be attributed to sludge pellet formation and degradation of extracellular polymeric substances, in particular the slime-EPS and loosely-bound EPS (LB-EPS). With the addition of fungal mycelium into the either sterilized sludge or non-sterilized sludge, the values of CST decreased by 74.0% and 43.7%, respectively, suggesting the fungal mycelium can improve the sludge dewaterability. After conditioned by the mycelium, the sludge cake by the diaphragm filter press was thicker and showed less water content than the control sludge. The results in this study demonstrated that the Talaromyces flavus S1 can serve as an environmentally friendly biological dewatering agent and has a promising application potential in the future.