Eckhard Schollmeyer

Inhibition of microbial pathogens by fungal chitosan

Four fungal chitosan types (CTS) were prepared from Mucor rouxii DSM 1191 and examined for their physico-chemical characteristics. The antimicrobial activity of chitosan types against 11 bacterial strains, including six pathogens, was investigated and the most effective type was chitosan No. 3 which was characterized with the lowest viscosity and molecular weight (3.1 cP and 2.1 x 10(4)Da, respectively), the highest degree of deacetylation (95%) and neutral water solubility. Gram positive bacteria were generally more sensitive to chitosan antimicrobial action than Gram negative strains and this action was notably affected by the environmental growth conditions, i.e. incubation temperature and pH value. The applications of fungal chitosan for the suppression of bacterial pathogens as a natural alternative, reduced risk and biodegradable biocidal agent could be recommended.

Anticandidal action of fungal chitosan against Candida albicans

The anticandidal activity of four fungal chitosan types, produced from Mucor rouxii DSM-1191, against three Candida albicans strains was determined. The most bioactive chitosan type, to inhibit C. albicans growth, had the lowest molecular weight (32 kDa) and the highest deacetylation degree (94%). Water soluble types had stronger anticandidal activity than soluble types in 1% acetic acid solution. Scanning electron micrographs of treated C. albicans with fungal chitosan proved that chitosan principally interact with yeast cell wall, causing severe swelling and asymmetric rough shapes, and subsequent cell wall lyses with the prolonging of exposure time. Fungal chitosan could be recommended for C. albicans control as a powerful and safe alternative to synthetic and chemical fungicides.

ZnO-modified hybrid polymers as an antibacterial finish for textiles

The antibacterial activity of ZnO is reported by several authors. We present the preparation and application of inorganic–organic hybrid polymers modified/filled with ZnO nanoparticles of varying particle sizes. Inorganic–organic hybrid polymers employed here are based on 3-glycidyloxypropyltrimethoxysilane (GPTMS). ZnO is prepared by hydrolysis of zinc acetate in different solvents (methanol, ethanol or 2-propanol) using lithium hydroxide (LiOHu2009ċu2009H2O). The hybrid materials prepared are applied to cotton (100%) and cotton/polyester (65/35%) fabrics. The antibacterial performance of these sol-gel derived hybrid materials is exemplarily investigated against Gram-negative bacterium Escherichia coli and Gram–positive Micrococcus luteus. Effects of particle size and concentration for the antibacterial performance are examined. Literature discusses various (active) species and processes responsible for the antibacterial action of ZnO. Therefore, particular attention is paid to investigate active species available in the described systems as well as to observe possible interaction between the nanoparticles and bacteria; the first results are presented.

Photo-chemical Surface Modification for the Control of Protein Adsorption on Textile Substrates

Cell growth on fiber surfaces is an important aspect of many applications of technical textiles. The need to prevent clogging in artificial blood vessels or in textiles used for blood or water filtration as well as the anti-fouling properties of outdoor technical textiles are examples in this context. Since the adsorption of proteins forms the initial step of cell growth, a promising way to avoid biofouling is to prohibit protein adsorption by means of a suitable, permanent and non-toxic surface functionalization. Today, the deposition of poly(ethylene glycol)s (PEGs) is a well-known approach to decrease non-specific protein adsorption. In this work, a photo-chemical method to graft or cross-link PEGs on fiber surfaces was studied. Monomethacrylated PEG300MA and PEG2080MA as well as dimethacrylated PEG400DMA and PEG600DMA were considered, the numbers indicate average molar mass in g/mol. Textile fabrics made of poly(ethylene terephthalate) (PET) were impregnated with solutions of the PEGs and irradiated using either a KrCl* or a XeCl* excimer lamp (emission wavelengths 222 or 308 nm, respectively). Surface properties of the treated textiles were characterized as a function of process conditions using various surface sensitive analyses. UV cross-linking of PEG400DMA resulted in the deposition of a thick layer which effectively masked the texture of the fabric and its pore system. Much less coverage was observed in case of monomethacrylated PEGMAs, with a significant reduction in drop penetration time already after deposition of a marginal layer (less than 0.01 mg/mg). Highest reductions in adsorption of bovine serum albumin (BSA) were observed for samples prepared using PEG300MA or PEG400DMA under conditions where also the drop penetration time was at its minimum. The longer chain PEG2080MA was less effective. All results show clearly that the protein adsorption tendency can be significantly reduced by choice of suitable combinations of PEGylated monomer and UV irradiation conditions.

Antibacterial action of acetic acid soluble material isolated from Mucor rouxii and its application onto textile

Acetic acid soluble material (AcSM) is a chitosan-rich fraction isolated from the fungal cell wall materials. The final step in the traditional production of fungal chitosan is the separation of chitosan from the cell wall AcSM via raising the pH to 9-10 followed by centrifugation. This step results in further undesirable economic and environmental effects. The goal of this paper is to avoid that by investigating the antimicrobial effect of the whole AcSM from Mucor rouxii DSM-1191 cell wall and its application on cotton fabrics. The treated fabrics were characterized through monitoring the textile physical properties and for the antibacterial activity against Escherichia coli and Micrococcus luteus. Results showed that Mucor rouxii DSM-1191 has excellent potentials to be used for cell wall AcSM production on industrial scale with a maximum content of 40% in dry mycelia. The obtained results indicated that the physical properties of the treated fabrics, as well as the antibacterial activity, were improved after treatment with fungal AcSM.

The Use of FTIR Microspectroscopy for the Identification of Thermally Changed Fibers

The analysis of thermally changed, e.g., melted, decomposed, burned, or incinerated textile fibers by FTIR spectroscopy is described. This method allows us to observe the pathway of fiber thermal degradation and to find the chemical (organic and inorganic) compounds in degraded fibers. The results of these examinations can be applied in the forensic analysis for the identification and differentiation between thermally changed fibers.

Computer simulation of the filtration process in a fibrous filter collecting polydisperse dust

Abstract The characteristics of a fibrous filter collecting polydisperse dust were estimated using the Monte Carlo method. A simple structure of parallel cylindrical fibres was chosen as model of the filter. This assumption made it possible to derive the filtration properties from single fibre collection of particles. Herein only inertial and interceptional forces were considered. To take account of polydisperse real dusts a model aerosol consisting of eight size fractions was used in the simulation. Each time a particle was generated, its size was chosen by a random number. This way it was possible to study the filter cake build up and its influence on filtration properties. The simulation results were used to estimate the total collection efficiency and the dependence of the collection efficiency of the filter on particle size. Calculated quantities were in close agreement with experimental observations. Furthermore, the deposition of dust particles in filter and filter cake was studied and compared with SEM micrographs taken of a dusted filter. The Monte Carlo results, as well as SEM micrographs, indicate that deposition of particles takes place mainly near the dust side surface of the filter and, of course, in the filter cake.

Generation of methane from textile desizing liquors.

A new strategy for the biological transformation of sugar‐containing wastewaters from the textile desizing process to biogas was developed. Here, industrial liquors were separated from the following washing step by squeezing the impregnated fabrics after desizing. These waters exhibit a chemical oxygen demand of 40u2009g/L and allow a direct use in microbial biogas reactors without further treatment or accumulation. After reaching balanced conditions, the microbes continuously produce biogas. Moreover, the chemical oxygen demand can be reduced up to 75%. This new technology seems to be practicable and even attractive for small‐ and medium‐sized enterprises with an annual cotton production down to 2000u2009t. At this stage, a reliable eco‐balance of the overall process is still pending. Further investigations will be carried out soon.