Potential of essential oil combinations for surface and air disinfection

In this study, it was aimed to develop a novel disinfectant from various essential oils containing active components with antimicrobial activity. The mixture of oregano, cinnamon and clove oils (1 : 1 : 1) with 10% oil concentration (SOM) was used as potential disinfectant on various areas and showed the highest antimicrobial activity among oil combinations tested. SOM reduced the numbers of total mesophilic aerobic bacteria (TMAB; 2·27 log CFU per 25 cm²) and Escherichia coli (4·60 log CFU per 25 cm²) under the detection limits. Application of SOM (1, 2, 3, 4 and 6%) into incubators reduced TMAB and mould-yeast counts of incubator air by 82·9 and 100% respectively. SOM application (3%) into ambient air also reduced its TMAB and mould-yeast counts by 92 and 84·6% respectively. While ethanol is commonly used for the disinfection of environments, equipment and surfaces, SOM is an important alternative that may also be used for the disinfection of various surfaces as well as air.     

Combination of high‐frequency ultrasound and UV radiation of excilamp for surface disinfection

The combination of high‐frequency ultrasound (HFUS) and UV represents a new approach to disinfecting surfaces. This study aimed to examine the inactivation efficiency of HFUS (1.7 MHz) and monochromatic UV radiation of KrCl excilamp (222 nm) in a single and a sequential mode against Bacillus cereus cells and spores added to glass surfaces. When treated by UV only, cells at populations of 10³, 10⁴, and 10⁵ colony‐forming units (CFU)/cm² showed 100% disinfection at high doses up to 1760 mJ/cm². Spores at 10⁴ CFU/cm² were completely inactivated at a dose of 1170 mJ/cm². Treatment with aqueous aerosol (produced by HFUS) reduced cell counts by 100% within a 40‐min exposure, whereas it was ineffective in inactivating spores under these conditions. In a sequential mode, the contaminated surface was pretreated with the sonicated aqueous aerosol and subsequently irradiated with the excilamp. It was found that HFUS exposure times and UV doses for complete inactivation decreased by a factor of 2 and 6–7, respectively, compared to sole HFUS or UV. A portable apparatus for surface disinfection was designed. The combined HFUS/UV method may be a promising technique for rapid disinfection of microbially contaminated surfaces.     

Effect of a disinfection strategy on the methicillin‐resistant Staphylococcus aureus CC398 prevalence of sows,their piglets and the barn environment

Aims

To assess, in a cleaned and disinfected barn environment, the efficacy of an animal disinfection strategy to reduce the livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA) prevalence in sows, their offspring and the barn environment.

Methods and Results

On each farm, six sow rounds were sampled; sows were divided into either a test or control group. Per round, 20 sows and 40 of their piglets were sampled at different time points together with the barn environment. The disinfection strategy of the test groups consisted of washing the sows with a shampoo followed by disinfection of the skin with a solution containing chlorhexidine digluconate and isopropanol. On the first day of disinfection and 6 days after stopping the disinfection, a significant decrease (P < 0·01) of on average 68 and 66% in sow MRSA prevalence was observed on both farms, whereas no decrease was seen in the control groups. Just before weaning, 21–28 days after the end of the disinfection strategy, the difference in MRSA prevalence between both groups was reduced to 4% and no longer significant (P = 0·20). The MRSA prevalence of the piglets in the test groups was significantly lower (26%; P < 0·01) 6 days after the end of disinfection. Just before weaning, this difference was reduced to 5% but still significant (P < 0·01). In the swine nursery unit, no significant difference (P = 0·99) was seen between both groups. Based on semi‐quantitative counts, a relationship (r² > 0·6; P < 0·01) was seen between MRSA contamination in the barn environment and the MRSA prevalence in pigs.

Conclusion

Results show that the tested disinfection strategy reduces temporarily the sow and piglet MRSA status, but does not result in a final reduction in MRSA at weaning or in the nursery unit.

Significance and Impact of the Study

First report on the efficacy of an animal disinfection strategy to reduce LA‐MRSA prevalence in sows, their offspring and the barn environment.     

Microbial Communities Associated with Tree Bark Foliose Lichens: A Perspective on their Microecology

Tree‐bark, foliose lichens occur widely on a global scale. In some locales, such as forests, they contribute a substantial amount of biomass. However, there are few research reports on microbial communities including eukaryotic microbes associated with foliose lichens. Lichens collected from tree bark at 11 locations (Florida, New York State, Germany, Australia, and the Arctic) were examined to determine the density and C‐biomass of bacteria and some eukaryotic microbes, i.e. heterotrophic nanoflagellates (HNF) and amoeboid protists. A rich microbial diversity was found, including large plasmodial slime molds, in some cases exceeding 100 μm in size. The densities of HNF and amoeboid protists were each positively correlated with densities of bacteria, r = 0.84 and 0.80, respectively (p < 0.01, N = 11 for each analysis) indicating a likely bacterial‐based food web. Microbial densities (number/g lichen dry weight) varied markedly across the geographic sampling sites: bacteria (0.7–13.1 × 10⁸), HNF (0.2–6.8 × 10⁶) and amoeboid protists (0.4–4.6 × 10³). The ranges in C‐biomass (μg/g lichen dry weight) across the 11 sites were: bacteria (8.8–158.5), HNF (0.03–0.85), and amoeboid protists (0.08–540), the latter broad range was due particularly to absence or presence of large slime mold plasmodia.     

Evaluation of the efficacy of chemical disinfectants for disinfection of heat‐polymerised acrylic resin

doi: 10.1111/j.1741‐2358.2010.00400.x
Evaluation of the efficacy of chemical disinfectants for disinfection of heat‐polymerised acrylic resin Objective: This study evaluated the efficacy of disinfectants on the internal aspect of heat‐polymerised acrylic resin contaminated with microbial strains. Background: Dentures absorb oral fluids and become contaminated by different microorganisms. Methods: Two hundred and fifty rectangular specimens were made of heat‐polymerised acrylic resin, and then divided into five groups corresponding to the microbial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, S. mutans and Enterococcus faecalis). After contamination, the specimens were immersed in 1 and 2% sodium hypochlorite and 2% glutaraldehyde for periods of 5, 10 and 15 min. The specimens were placed into tubes containing different broths and incubated at 35°C and then visually analysed. Turbidity in the medium indicated microbial growth. The Fisher’s exact test was used in the analysis of the results. Results: The strain E. faecalis was the most resistant to the disinfectant solutions, and among them, glutaraldehyde was more effective than 2 and 1% hypochlorite for disinfection for 5 min; in the 10‐min period there were no differences between the disinfectants. In 15 min of immersion, 1% hypochlorite and glutaraldehyde were more effective than 2% hypochlorite. Conclusions: Disinfection for 10 min with 1% hypochlorite and glutaraldehyde is effective in disinfecting the internal aspect of heat‐polymerised acrylic resin.     

Optimization of exopolysaccharide production and diesel oil emulsifying properties in root nodulating bacteria

Bioremediation, a strategy mediated by microorganisms, is a promising way used in the degradation or removal of organic contaminants from soil or aquatic system. Exopolysaccharide (EPS) which was produced by a variety of Gram-negative bacteria has been demonstrated to be a potential bioemulsifier used in the degradation of hydrocarbons. In the present study, attempts were made to optimize the production of EPS from our newly isolates by adjusting the culture conditions and medium components. Besides, the performance of diesel oil emulsification using partially purified EPS derived from different conditions was also demonstrated. Out of 40 root nodulating bacteria the better emulsifying abilities were recorded from three strains namely Rhizobium miluonense CC-B-L1, Burkholderia seminalis CC-IDD2w and Ensifer adhaerens CC-GSB4, as can be seen from their emulsification index (E₂₄) 66, 64 and 60%, respectively. These three strains produced 212, 203 and 198 mg l⁻¹ of EPS, respectively, in yeast extract mannitol (YEM) medium. After modifying culture conditions, better performances can be achieved from these three strains, with increases of 21.7, 21.4, 16.7% in the EPS production and 12.1, 10.9, 8.3% in E₂₄, respectively. When considered for strain CC-B-L1 and CC-IDD2w, the addition of 1.5% (v/v) of mannitol and 0.1% (v/v) of asparagine in YEM enhanced 42.9 and 34.7% in EPS production along with 28.8 and 37.5% higher in E₂₄. The supplement of 2.0% (v/v) glucose and 0.2% (v/v) asparagine in YEM increased 65.2% of EPS and 38.3% of E₂₄ in strain CC-GSB4. This is the first report demonstrating the optimization of diesel emulsification by EPS from root nodulating isolates, and these microbial agents might be used in the remediation of hydrocarbon contaminated soils in a near future.     

Identification of bacterial species on Lippia multiflora herbal tea leaves and the influence of steam pasteurization

The consumption of herbal teas is an increasing phenomenon among tea consumers globally. Some of these herbal teas are not pre-treated to reduce their microbial load before consumption, and thus constitute a health risk to consumers. In this study, the effect of steam pasteurization, at >99 °C for 2.5 min, on the microbial load of Lippia multiflora herbal tea leaves was evaluated. Microbial enumeration was conducted on potato dextrose agar, plate count agar, violet red bile agar, yeast peptone dextrose agar, and DeMan-Rogosa-Sharpe agar. Morphologically distinct colonies were isolated, sub-cultured and their Gram reaction recorded. These bacteria were identified to the species level using 16S ribosomal DNA sequence data. Most of the bacteria identified belonged to the genus Bacillus. One species each from the genera Pantoea and Kocuria was also identified, but only the Bacillus species survived the steam pasteurization treatment. Coliform bacteria detected prior to pasteurization were not detected after the steam treatment. Steam pasteurization reduced the microbial load from 10⁴ to 10² c.f.u.g⁻¹and it is potentially an effective method to treat L. multiflora herbal teas prior to consumption. It is important to note that the steam treatment should complement good agricultural and hygienic practices rather than replace them, as some bacteria can survive this treatment.     

Disinfectant test against monoculture and mixed-culture biofilms composed of technological, spoilage and pathogenic bacteria: bactericidal effect of essential oil and hydrosol of Satureja thymbra and comparison with standard acid-base sanitizers

Aims: To assess the antimicrobial action of three natural‐derived products (essential oil, decoction and hydrosol of Satureja thymbra) against biofilms, composed of useful, spoilage and pathogenic bacteria (formed as monoculture or/and mixed‐culture), and to compare their efficiency with three standard acid and alkaline chemical disinfectants. Methods and Results: Two acids (hydrochloric and lactic, pH 3), one alkali (sodium hydroxide, pH 11), the essential oil of S. thymbra (1% v/v) and the two by‐products of the essential oil purification procedure (the decoction and the hydrosol fraction of essential oil, 100%), were tested against biofilms formed by five bacterial species, either as monospecies, or as mixed‐culture of all species. The tested bacterial species were Staphylococcus simulans and Lactobacillus fermentum (useful technological bacteria), Pseudomonas putida (spoilage bacterium), Salmonella enterica and Listeria monocytogenes (pathogenic bacteria). Biofilms were left to be formed on stainless steel coupons for 5 days at 16°C, before the application of disinfection treatments, for 60 and 180 min. The disinfection efficiency was evaluated by detaching the remaining viable biofilm cells and enumerating them by agar plating, as well as by automated conductance measurements (using Rapid Automated Bacterial Impedance Technique). Both these methods revealed that the essential oil and the hydrosol of S. thymbra exhibited a strong antimicrobial action against both monospecies and mixed‐culture biofilms. Surprisingly, the efficiency of the other three acid–base disinfectants was not adequate, although a long antimicrobial treatment was applied (180 min). Conclusions: The essential oil of S. thymbra (1%), as well as its hydrosol fraction (100%), presents sufficient bactericidal effect on bacterial biofilms formed on stainless steel. Significance and Impact of the Study: Use of natural antimicrobial agents could provide alternative or supplemented ways for the disinfection of microbial‐contaminated industrial surfaces.     

Improving probiotic spore yield using rice straw hydrolysate

Spore-forming Bacillus sp. has been extensively studied for their probiotic properties. In this study, an acid-treated rice straw hydrolysate was used as carbon source to produce the spores of Bacillus coagulans. The results showed that this hydrolysate significantly improved the spore yield compared with other carbon sources such as glucose. Three significant medium components including rice straw hydrolysate, MnSO₄ and yeast extract were screened by Plackett–Burman design. These significant variables were further optimized by response surface methodology (RSM). The optimal values of the medium components were rice straw hydolysate of 27% (v/v), MnSO₄ of 0·78 g l⁻¹ and yeast extract of 1·2 g l⁻¹. The optimized medium and RSM model for spore production were validated in a 5 l bioreactor. Overall, this sporulation medium containing acid-treated rice straw hydrolysate has a potential to be used in the production of B. coagulans spores.     

Ochratoxin A production in aniseed-based media by selected fungal strains and in anise fruits (<Emphasis Type="Italic">Pimpinella anisum</Emphasis> L.)

The growth conditions and ochratoxin A (OTA) production of Aspergillus strains were studied in aniseed (Pimpinella anisum L.)-based media. The results showed that methanol/NaHCO₃ (50:50, v/v) mixture for extraction and competitive direct ELISA analytical method are capable of detecting low OTA concentrations in this raw material, which were confirmed by HPLC with fluorescence detection (R ² = 0.994). In aniseed meal extract agar artificially contaminated with selected fungi, the higher OTA values obtained were 283.8 ± 28.1 μg L^-1 for A. carbonarius and between 1.7 ± 0.1 μg L^-1 and 16.5 ± 12.8 μg L^-1 for A. steynii strains. While the optimal conditions of growth for A. carbonarius and A. steynii are 28°C and 0.98 a _w, the optimal production of OTA was observed at 0.99 a _w for both A. carbonarius and A. steynii but at 22°C and 28°C, respectively. Except in one sample, all the aniseed samples analysed were negative for OTA natural contamination. This study demonstrates that aniseed can be a matrix capable to contamination with OTA, at least produced by A. carbonarius and A. steynii strains, regardless of the antimicrobial properties of aniseed essential oil.     

Chlorine disinfection of Francisella tularensis

Aims: To determine the range of free available chlorine (FAC) required for disinfection of the live vaccine strain (LVS) and wild‐type strains of Francisella tularensis. Methods and Results: Seven strains of planktonic F. tularensis were exposed to 0·5 mg·l^?1 FAC for two pH values, 7 and 8, at 5 and 25°C. LVS was inactivated 2 to 4 times more quickly than any of the wild‐type F. tularensis strains at pH 8 and 5°C. Conclusions: Free available chlorine residual concentrations routinely maintained in drinking water distribution systems would require up to two hours to reduce all F. tularensis strains by 4 log₁₀. LVS was inactivated most quickly of the tested strains. Significance and Impact of the Study: This work provides contact time (CT) values that are useful for drinking water risk assessment and also suggests that LVS may not be a good surrogate in disinfection studies.     

In Vitro Sensitivity of <Emphasis Type="Italic">Rhizobium</Emphasis> and Phosphate Solubilising Bacteria to Herbicides

Nitrogen fixing bacteria, rhizobia and phosphate solubilizing bacteria (PSB) are the commonly applied microbial inoculants in grain legumes (Pulses). It is important to apply herbicides to control weeds in order to augment yield of the crop. The herbicides may however, be incompatible with the microbial inoculants. This study compared the effect of the recommended pre-plant incorporated herbicide, fluchloralin (20.25 × 10⁴ ppm) and pre-emergence herbicide, pendimethalin in two doses (9 × 10⁴ and 15 × 10⁴ ppm) on the growth and survival of mungbean Rhizobium and PSB, under laboratory conditions. These herbicides were also used under field conditions in conjunction with biofertilizers (R, PSB) to improve grain yield of mungbean. It was found that fluchloralin (20.25 × 10⁴ ppm) and the lower dose of pendimethalin (9 × 10⁴ ppm) had no adverse effect on growth of Rhizobium and PSB. The higher dose of pendimethalin (15 × 10⁴ ppm) was safe on PSB but it imposed a retarding effect on the growth of Rhizobium.     

Development of a real-time TaqMan assay to detect <Emphasis Type="Italic">mendocina</Emphasis> sublineage <Emphasis Type="Italic">Pseudomonas</Emphasis> species in contaminated metalworking fluids

A TaqMan quantitative real-time polymerase chain reaction (qPCR) assay was developed for the detection and enumeration of three Pseudomonas species belonging to the mendocina sublineage (P. oleovorans, P. pseudoalcaligenes, and P. oleovorans subsp. lubricantis) found in contaminated metalworking fluids (MWFs). These microbes are the primary colonizers and serve as indicator organisms of biodegradation of used MWFs. Molecular techniques such as qPCR are preferred for the detection of these microbes since they grow poorly on typical growth media such as R2A agar and Pseudomonas isolation agar (PIA). Traditional culturing techniques not only underestimate the actual distribution of these bacteria but are also time-consuming. The primer–probe pair developed from gyrase B (gyrB) sequences of the targeted bacteria was highly sensitive and specific for the three species. qPCR was performed with both whole cell and genomic DNA to confirm the specificity and sensitivity of the assay. The sensitivity of the assay was 10¹ colony forming units (CFU)/ml for whole cell and 13.7 fg with genomic DNA. The primer–probe pair was successful in determining concentrations from used MWF samples, indicating levels between 2.9 × 10³ and 3.9 × 10⁶ CFU/ml. In contrast, the total count of Pseudomonas sp. recovered on PIA was in the range of <1.0 × 10¹ to 1.4 × 10⁵ CFU/ml for the same samples. Based on these results from the qPCR assay, the designed TaqMan primer–probe pair can be efficiently used for rapid (within 2 h) determination of the distribution of these species of Pseudomonas in contaminated MWFs.     

Purification,biochemical characterization and gene sequencing of a thermostable raw starch digesting α-amylase from Geobacillus thermoleovorans subsp. stromboliensis subsp. nov.

This study reports the purification and biochemical characterization of a raw starch-digesting α-amylase from Geobacillus thermoleovorans subsp. stromboliensis subsp. nov. (strain Pizzo^T). The molecular weight was estimated to be 58 kDa by SDS–PAGE. The enzyme was highly active over a wide range of pH from 4.0–10.0. The optimum temperature of the enzyme was 70°C. It showed extreme thermostability in the presence of Ca²⁺, retaining 50% of its initial activity after 90 h at 70°C. The enzyme efficiently hydrolyzed 20% (w/v) of raw starches, concentration normally used in starch industries. The α-amylase showed an high stability in presence of many organic solvents. In particular the residual activity was of 73% in presence of 15% (v/v) ethyl alcohol, which corresponds to ethanol yield in yeast fermentation process. By analyzing its complete amyA gene sequence (1,542 bp), the enzyme was proposed to be a new α-amylase.     

Determination of the effectiveness of UV radiation as a means of disinfection of metalworking fluids

Microbial contamination of metalworking fluids (MWFs) causes biofouling and degradation and is also associated with several health hazards. Development of an effective control method is therefore essential to reduce microbial loading in MWFs. The present study investigated the efficacy and rapidity of UV radiation as a means of disinfection of MWFs under laboratory conditions to determine parameters that could be used to design an in-line UV reactor for enclosed machines. High and low concentrations (10⁴–10⁷ CFU/mL) of three indicator bacteria, Pseudomonas fluorescens, P. oleovorans subsp. lubricantis and Mycobacterium chelonae, were evaluated both as pure cultures and in combinations. The target organisms were irradiated with a high intensity (192 μW/cm², 55 W) UV lamp for different exposure time under both static and mixed conditions. For these Pseudomonas species with high concentrations of cells under static conditions, only a 56 % reduction was observed within 10 min of exposure, whereas under mixed condition, a 99 % reduction was achieved within 2 min of exposure. In contrast only 74 % reduction was observed for M. chelonae. However, with low concentrations of cells under mixed conditions, a 99.99 % and 82 % reduction in viable count was observed for the Pseudomonas sp. and M. chelonae, respectively. Similar results were observed for mixed culture combinations. Based on these observations high intensity UV in combination with mixing could be successfully used as a means of disinfection of MWFs within a short exposure time and the parameters obtained from the study could be implemented to design a plug flow UV reactor.     

The effects of cleaning and disinfection in reducing Salmonella contamination in a laboratory model kitchen

AIMS: To establish a laboratory model to compare the effectiveness of detergent-based disinfection procedures for reducing cross-contamination risks during handling of contaminated chicken. METHODS AND RESULTS: During handling of chickens, artificially contaminated with Salmonella enteritidis PT4, the organism was widely spread to hands, cloths, and hand- and food-contact surfaces. Hygiene procedures were assessed on the basis of their ability to reduce the number of recoverable salmonellas to <1 CFU. Although detergent-based cleaning using a typical bowl-wash routine without rinsing produced some risk reduction (from 100 to 61.4% of contaminated surfaces), it was insufficient to consistently restore surfaces to a hygienic state. By combining detergent-based cleaning with a rinsing step or with hypochlorite at 500 ppm (of available chlorine) some further reduction in microbial risk was achieved, but was not considered satisfactory for food hygiene purposes. By contrast the risk reduction produced by hypochlorite at 5000 ppm was highly significant and was sufficient to reduce the number of contaminated surfaces to 2.9%. CONCLUSIONS: A key step in achieving a hygienic state through detergent-based cleaning is rinsing but even this will not produce a 'hygienic' result for difficult surfaces such as the chopping board or the dishcloth. Disinfectant compounds should be considered in order to reduce the potential for foodborne cross infection within the home environment. SIGNIFICANCE AND IMPACT OF THE STUDY: Although tests are available to determine the performance of disinfectants, there are no quantitative procedures available to compare the risk reduction achieved by disinfection with that produced by detergent-based procedures. This study describes a reproducible laboratory method which can be used to differentiate the effectiveness of different hygiene procedures for reducing cross-contamination risks during food handling.     

Efficacy of Conventional Endoscopic Disinfection and Sterilization Methods Against Helicobacter pylori Contamination

Background. Iatrogenic transmission of Helicobacter pylori via contaminated endoscopic devices is well documented. Despite the prevalence of this infectious agent, few controlled studies have investigated the major factors that impact on reprocessing of endoscopes contaminated with H. pylori. Materials and Methods. An endoscope (Pentax) was contaminated with 10⁸ cfu/ml of H. pylori in 5% bovine calf serum as standardized inoculum. The endoscope then was passed through one of eight arms (five repetitions per arm = 40 total runs), as follows: 1, recovery control (no cleaning or disinfection); 2, manual cleaning alone; 3–5, manual precleaning followed by either 10-, 20-, or 45-minute exposure to 2% glutaraldehyde and ethanol (ETOH) drying; 6, manual cleaning followed by automated reprocessing by STERIS System; 7 and 8, automated reprocessing by STERIS with and without active peracetic acid sterilant (wash-off control). Suction-biopsy channels and air-water channels were harvested for microbiological culture. Results. Control runs recovered more than 1 × 10⁶ cfu per site, confirming the viability of the test organism and the adequacy of the biological burden for challenge. When instruments underwent manual cleaning alone (without subsequent disinfection), test organisms remained in 40% of runs at the air-water site. Manual cleaning followed by 10-, 20-, or 45-minute glutaraldehyde exposure and ETOH drying removed all test organisms from all sites in all runs (i.e., 100% disinfection). The automated STERIS system with or without active peracetic acid sterilant also removed all test organisms from all sites in all runs, as did manual cleaning followed by STERIS use. Conclusion. Manual cleaning alone does not effectively remove H. pylori from an endoscope. Current joint association recommendations for minimal disinfection (manual cleaning followed by at least 20 minutes of immersion in glutaraldehyde and ETOH drying) are effective in preventing cross-transmission of H. pylori. Reprocessing using the automated STERIS system according to manufacturer's recommendations also is highly effective in sterilizing endoscopes contaminated with H. pylori.     

Determining the disinfection of textiles in compressed carbon dioxide using various indicator microbes

Aims: This paper presents a research on the disinfection efficiency of inoculated textile swatches by compressed carbon dioxide, an environmental friendly way to disinfect textiles as opposed to the conventional laundering procedures using water. The disinfection efficiency was determined by using the following microbes inoculated on cotton test fabrics: Enterococcus faecium, Enterobacter aerogenes and Candida albicans. Methods and Results: The experiments were performed using the high pressure extraction device with a maximum pressure of 50 MPa and a small extraction vessel of 500 ml. Pure CO₂ and CO₂ with added disinfection agent or commercial detergent were used. The chosen disinfecting agent was hydrogen peroxide, a widespread disinfecting chemical. It was found that treatment with CO₂ for 25 min at 5 MPa and 40°C (313K) and the addition of 4 ml of specific detergent per litre of CO₂ assures at least a five log step reduction of Enterobacter aerogenes and C. albicans, whilst treatment at 50°C (323K) with CO₂ for 25 min at 5 MPa is sufficient for at least a five log step reduction for Enterococcus faecium. It was also found that a 15‐min CO₂ treatment at 7 MPa and 20°C (293K) was sufficient for the inactivation of the yeast C. albicans, whilst these conditions were not rigorous enough for the challenge bacteria. On the other hand, the labscale treatment with CO₂ for 25 min at pressure 4 and 6 MPa with the addition of detergent or hydrogen peroxide only yields a log step reduction of up to 4 log steps, thus proving the slightly disinfective properties of the CO₂ treatment with added agents, but not reaching efficient results as a 5 log step reduction was not reached. Conclusions: Addition of heat to the compressed CO₂ treatment of textiles inoculated with microorganisms proved more effective than the addition of detergent or disinfectant with compressed CO₂ treatment at temperature of 20°C. Significance and Impact of the Study: CO₂ treatment of textiles is a promising ecological alternative dry‐cleaning method for the disinfection of medical textiles.     

Successful disinfection of femoral head bone graft using high hydrostatic pressure

The current standard for sterilization of potentially infected bone graft by gamma irradiation and thermal or chemical inactivation potentially deteriorates the biomechanical properties of the graft. We performed an in vitro experiment to evaluate the use of high hydrostatic pressure (HHP); which is widely used as a disinfection process in the food processing industry, to sterilize bone grafts. Four femoral heads were divided into five parts each, of which 16 were contaminated (in duplicate) with 10⁵–10⁷ CFU/ml of Staphylococcus epidermidis, Bacillus cereus, or Pseudomonas aeruginosa or Candida albicans, respectively. Of each duplicate, one sample was untreated and stored similarly as the treated sample. The remaining four parts were included as sterile control and non-infected control. The 16 parts underwent HHP at the high-pressure value of 600 MPa. After HHP, serial dilutions were made and cultured on selective media and into enrichment media to recover low amounts of microorganism and spores. Three additional complete femoral heads were treated with 0, 300 and 600 MPa HHP respectively for histological evaluation. None of the negative-control bone fragments contained microorganisms. The measured colony counts in the positive-control samples correlated excellent with the expected colony count. None of the HHP treated bone fragments grew on culture plates or enrichment media. Histological examination of three untreated femoral heads showed that the bone structure remained unchanged after HHP. Sterilizing bone grafts by high hydrostatic pressure was successful and is a promising technique with the possible advantage of retaining biomechanical properties of bone tissue.     

Diversity of lactic acid bacteria and yeasts in Airag and Tarag,traditional fermented milk products of Mongolia

We used culture- and molecular-biology-based methods to investigate microbial diversity in the traditional Mongolian fermented milks “Airag” (fermented mare’s milk) and “Tarag” (fermented milk of cows, yaks, goats, or camels). By rRNA or functional gene sequencing, we identified 367 lactic acid bacteria (LAB) strains and 152 yeast strains isolated from 22 Airag and 31 Tarag samples. The total concentration of LAB in Airag (10^{7.78 ± 0.50} c.f.u. ml^–1; mean ± SD) was significantly lower (P < 0.01) than in Tarag (10^{8.35 ± 0.62} c.f.u. ml⁻¹), whereas the total concentration of yeasts in Airag (10^{7.41 ± 0.61} c.f.u. ml^-1) was significantly higher (P < 0.01) than in Tarag (10^{5.86 ± 1.29} c.f.u. ml^-1). Lactobacillus helveticus and Lactobacillus kefiranofaciens were isolated from Airag as the predominant LAB strains at levels of about 10⁷ c.f.u. ml⁻¹, whereas Lactobacillus delbrueckii subsp. bulgaricus, L. helveticus, and Streptococcus thermophilus were the predominant isolates from Tarag at about 10⁷ c.f.u. ml⁻¹. The lactose-fermenting Kluyveromyces marxianus was isolated predominantly from Airag as its major alcoholic fermentation component. Non-lactose-fermenting yeasts such as Saccharomyces cerevisiae, Issatchenkia orientalis, and Kazachstania unispora were the predominant isolates from Tarag, at about 10⁵ c.f.u. ml⁻¹. The apparent geographic differences in the L. kefiranofaciens and S. thermophilus contents of Tarag strongly suggested that differences among the animal species from which the milk was sourced, rather than geographic distances, were the most important factors influencing the diversity of the microbial composition of traditional fermented milks in Mongolia.