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The study of how micro-organisms detect and respond to different stresses has a long history of producing fundamental biological insights while being simultaneously of significance in many applied microbiological fields including infection, food and drink manufacture, and industrial and environmental biotechnology. This is well-illustrated by the large body of work on acid stress. Numerous different methods have been used to understand the impacts of low pH on growth and survival of micro-organisms, ranging from studies of single cells to large and heterogeneous populations, from the molecular or biophysical to the computational, and from well-understood model organisms to poorly defined and complex microbial consortia. Much is to be gained from an increased general awareness of these methods, and so the present review looks at examples of the different methods that have been used to study acid resistance, acid tolerance, and acid stress responses, and the insights they can lead to, as well as some of the problems involved in using them. We hope this will be of interest both within and well beyond the acid stress research community. [ABSTRACT FROM AUTHOR]

9.4 million People have swallowing problems in the US. In special needs populations, routine oral hygiene procedures such as tooth brushing can result in aspiration of microbial laden fluids leading to a significant systemic challenge. Aspiration may lead to pneumonia in susceptible populations. These circumstances indicate the need for innovative approaches to oral hygiene for special needs, convalescent, the elderly populations, and young children learning to brush who can ingest excess fluoride which causes mottled enamel. Methods include describing some of the design considerations of the new prototype fabrication and microbiological evaluation of this new device, as well a comparison study of the versions 2 and 3 of the oral care device. Results concluded that version 3.0 regarding patient ease of use was better in comparison to version 2, which was the major difference, and 90% in both groups said they would recommend the new toothbrush. In the microbiological evaluation no growth was seen on any plates containing samples from either the experimental or the control after 48 h of incubation. [ABSTRACT FROM AUTHOR]

This article presents future trends in research using microbiological methods to intensify bioprocesses for biogas production. The pretreatment by combinations of physical and chemical methods, such as cavitation and electrolysis, is considered. The approach of the article involved reviewing the residual area on the intensification technologies of anaerobic digestion with current methods to improve the quality and quantity of biogas. The most valuable reported positive results of the pretreatment of biological raw materials in the cavitation process were reviewed and are presented here. A model of the effect of electrolysis on the species diversity of bacteria in anaerobic digestion was developed, and changes in the dominance of the ecological and trophic systems were revealed on the basis of previous studies. The stimulating effect on biogas yield, reduction in the stabilization period of the reactor, and inactivation of microorganisms at lower temperatures is associated with different pretreatment methods that intensify anaerobic digestion. More research is recommended to focus on the electrolysis treatment of different types of waste and their ratios with optimization of regime parameters, as well as in combination with other pretreatments to produce biomethane and biohydrogen in larger quantities and in better qualities. [ABSTRACT FROM AUTHOR]

The interest in probiotics has increased rapidly the latest years together with the global market for probiotic products. Consequently, establishing reliable microbiological methods for assuring the presence of a certain number of viable microorganisms in probiotic products has become increasingly important. To assure adequate numbers of viable cells, authorities are enquiring for information on viability rates within a certain shelf-life in colony forming units (CFU). This information is obtained from plate count enumeration, a method that enables detection of bacterial cells based on their ability to replicate. Although performing plate count enumeration is one manner of assessing viability, cells can still be viable without possessing the ability to replicate. Thus, to properly assess probiotic viability, further analysis of a broader group of characteristics using several types of methods is proposed. In addition to viability, it is crucial to identify how well the cells in a probiotic product can survive in the gastrointestinal tract (GIT) and thus be able to mediate the desired health benefit while passing through the human body. A broad spectrum of different assay designs for assessing probiotic gastric tolerance have been used in research and quality control. However, the absence of any consensus on how to assess these qualities makes it difficult to compare between laboratories and to translate the results into in vivo tolerance. This review presents and discusses the complexity of assuring that a probiotic is suitable for beneficial consumption. It summarizes the information that can be subtracted from the currently available methods for assessment of viability and stress tolerance of a probiotic, hereby altogether defined as "activity." Strengths and limitations of the different methods are presented together with favorable method combinations. Finally, the importance of choosing a set of analyses that reveals the necessary aspects of probiotic activity for a certain product or application is emphasized. [ABSTRACT FROM AUTHOR]

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The Canadian reference method for the enumeration of Listeria monocytogenes (Health Canada method MFLP-74) was modified by the addition of a layer of non-selective tryptone soy agar (TSA) to the Oxford, Palcam, and (or) Rapid'L.mono selective agars, to improve the recovery of stressed L. monocytogenes from frozen foods. The performance of the standard selective agars versus the selective agars with an additional TSA agar layer (TAL agars) showed that for each of the frozen food items tested (vegetables, shrimp and meatballs), as well as for all data combined, L. monocytogenes counts were significantly higher (up to 20% higher) in TAL agars in relation to the standard agars ( p < 0.0001, α = 0.05). A selectivity assessment showed that the 50 inclusivity L. monocytogenes strains tested produced true positive reactions on the TAL agars, and the 30 exclusivity bacterial strains tested produced true negative results on the TAL agars, indicating that the specificity of the selective agars was not altered by the additional non-selective TSA layer. In light of the 2016 Listeria outbreak linked to frozen fruits and vegetables in the USA, the results of this method investigation seem to be timely and particularly important for the regulatory testing of frozen foods. [ABSTRACT FROM AUTHOR]

The contemporary state and main problems of chemical and microbiological technology for processing mineral resources are analyzed. The main problems are given for the use of technogenic raw material. Results are analyzed for pilot plant work using physicochemical geotechnology for opening up deposits of hard economic minerals. Promising areas are considered for development of technology using achievements of chemistry and microbiology for innovative development of the mining and metallurgical complex in the 21st century. [ABSTRACT FROM AUTHOR]

Bottled water can be contaminated by coliforms and/or Escherichia coli ( E. coli). These bacteria are considered as indicators of faecal pollution, and their detection in bottled water indicates the potential contamination by pathogenic enteric microorganisms. In recent decades, different methods were developed for the detection of coliforms and E. coli in drinking water and in bottled water including mineral water. Since 1976, the Italian regulation has defined microbiological methods to evaluate microbiological characteristics of mineral waters. Three different methods for the detection of coliforms and E. coli in bottled water were compared in this study: the Italian reference method, according to the 'Italian Ministerial Rule,' the ISO 9308-1:2002 method, and a new rapid method. The results have demonstrated that the ISO method 9308-1:2002 and the new rapid method are as sensitive and specific as Italian reference method, and that both could be used to evaluate the contamination level of coliform and E. coli in drinking water and in bottled water including mineral water. [ABSTRACT FROM AUTHOR]

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The urinary microbiome of healthy individuals and the way it alters with ageing have not been characterized and may influence disease processes. Conventional microbiological methods have limited scope to capture the full spectrum of urinary bacterial species. We studied the urinary microbiota from a population of healthy individuals, ranging from 26 to 90 years of age, by amplification of the 16S rRNA gene, with resulting amplicons analyzed by 454 pyrosequencing. Mid-stream urine (MSU) was collected by the "clean-catch" method. Quantitative PCR of 16S rRNA genes in urine samples, allowed relative enumeration of the bacterial loads. Analysis of the samples indicates that females had a more heterogeneous mix of bacterial genera compared to the male samples and generally had representative members of the phyla Actinobacteria and Bacteroidetes. Analysis of the data leads us to conclude that a "core" urinary microbiome could potentially exist, when samples are grouped by age with fluctuation in abundance between age groups. The study also revealed age-specific genera Jonquetella, Parvimonas, Proteiniphilum, and Saccharofermentans. In conclusion, conventional microbiological methods are inadequate to fully identify around two-thirds of the bacteria identified in this study. Whilst this proof-of-principle study has limitations due to the sample size, the discoveries evident in this sample data are strongly suggestive that a larger study on the urinary microbiome should be encouraged and that the identification of specific genera at particular ages may be relevant to pathogenesis of clinical conditions. [ABSTRACT FROM AUTHOR]

The urinary microbiome of healthy individuals and the way it alters with ageing have not been characterised and may influence disease processes. Conventional microbiological methods have limited scope to capture the full spectrum of urinary bacterial species. We studied the urinary microbiota from a population of healthy individuals, ranging from 26 to 90 years of age, by amplification of the 16S rRNA gene, with resulting amplicons analysed by 454 pyrosequencing. Mid-stream urine was collected by the 'clean-catch' method. Quantitative PCR of 16S rRNA genes in urine samples, allowed relative enumeration of the bacterial loads. Analysis of the samples indicates that females had a more heterogeneous mix of bacterial genera compared to the male samples and generally had representative members of the phyla Actinobacteria and Bacteroidetes. Analysis of the data leads us to conclude that a 'core' urinary microbiome could potentially exist, when samples are grouped by age with fluctuation in abundance between age groups. The study also revealed age-specific genera Jonquetella, Parvimonas, Proteiniphilum and Saccharofermentans. In conclusion, conventional microbiological methods are inadequate to fully identify around two-thirds of the bacteria identified in this study. Whilst this proof-of-principle study has limitations due to the sample size, the discoveries evident in this sample data are strongly suggestive that a larger study on the urinary microbiome should be encouraged and that the identification of specific genera at particular ages may be relevant to pathogenesis of clinical conditions. [ABSTRACT FROM AUTHOR]

The goal of the present study was to determine whether the commercial microbiological and tracer assays for the detection of antibiotics in the food were also useful and sensitive enough for testing water samples. Diffusion tests Delvotest® SP-NT and BRT-AiM showed the similar sensitivity to tested antibiotics in spiked water samples. Both tests showed the similar sensitivity to examined antibiotics in water as it was published in milk, while tracer assay BetaStar showed slightly higher minimum detection levels for penicillin and ampicillin but not for cloxacillin. The previous concentration of the samples by lyophilization took place to detect concentrations of antibiotics 100-fold lower than there were the minimum detection limits of the assays. The presence of inhibitory substances in surface and well samples was detected in 16 (16.3 %) cases out of 98 with both ampoule diffusion methods. The positive results were obtained at 15.0 % of surface water samples, while in well water the residues were found also in 16.9 % and 13.6 % samples, using Delvotest SP-NT and BRT-AiM, respectively. The β-lactams were detected with BetaStar in 7.5 % of surface water samples. The 12 wastewater samples from hospitals were contaminated with inhibitory substances in 45.5 % (Delvotest SP-NT) or in 36.4 % (BRT-AiM). [ABSTRACT FROM AUTHOR]

Food used to be and is still one of the key factors of human adaptation to surroundings. Human need for food is tightly connected with soil fertility, climate and finally with sources of nourishment. However, besides man, other living creatures, like microorganisms, insects, as well as other animals, know about available sources of nourishment on Earth. Human beings are the only species from the animal world that tend to adapt the surroundings to their particular needs. Apart from milk, the most appreciated foodstuff in nutrition, meat is very significant as well, because it is a source of easily digestible and biologically and energetically valuable ingredients. Therefore, meat is one of the most frequent foodstuffs in human nutrition and it is necessary to control it especially in places where people often eat. The results of the microbiological analysis of meat samples taken in 10 different fast food restaurants are shown in this study. The selected samples were analyzed using the standard microbiological method, and the results of the analysis show that all samples were microbiologically sound since the total number of bacteria in 1g of the sample was within acceptable limits. In favor to this is the fact that the pathogenic microorganisms harmful to human health were not found. [ABSTRACT FROM AUTHOR]

For the enumeration of Listeria monocytogenes in cold-smoked salmon, a sensitive enumeration method, based on membrane filtration followed by transfer of the filter on a selective medium, has been recently developed. An evaluation of this method was performed with several categories of foods likely to be contaminated with L. monocytogenes. The results obtained with the technique were compared with those from the reference EN ISO 11290-2 method and found to provide more precise results in the enumeration of L. monocytogenes from both artificially and naturally contaminated products. In most cases, the filtration method enabled a greater quantity of food to be examined (from around 0.5 to 14 g, instead of 0.01 to 0.1 g with the reference EN ISO 11290-2 method), thus greatly improving the sensitivity of the enumeration. [ABSTRACT FROM AUTHOR]

In this study ten laboratories in Greece compared the performance of reference method TTC Tergitol 7 Agar (with the additional test of b-glucuronidase production) with five alternative methods, to detect E. coli in water, in line with European Water Directive recommendations. The samples were prepared by spiking drinking water with sewage effluent following a standard protocol. Chlorinated and non-chlorinated samples were used. The statistical analysis was based on the mean relative difference of confirmed counts and was performed in line with ISO 17994. The results showed that in total, three of the alternative methods (Chromocult Coliform agar, Membrane Lauryl Sulfate agar and Trypton Bilex-glucuronidase medium) were not different from TTC Tergitol 7 agar (TTC Tergitol 7 agar vs Chromocult Coliform agar, 294 samples, mean RD% 5.55; vs MLSA, 302 samples, mean RD% 1; vs TBX, 297 samples, mean RD% 22.78). The other two alternative methods (Membrane Faecal coliform medium and Colilert 18/ Quantitray) gave significantly higher counts than TTC Tergitol 7 agar (TTC Tergitol 7 agar vs MFc, 303 samples, mean RD% 8.81; vs Colilert-18/Quantitray, 76 samples, mean RD% 18.91). In other words, the alternative methods generated performance that was as reliable as, or even better than, the reference method. This study will help laboratories in Greece overcome culture and counting problems deriving from the EU reference method for E. coli counts in water samples. [ABSTRACT FROM AUTHOR]

The control of pathogenic bacteria present in foods, as well as scientific data concerning their behavior, are closely linked to analytical methods used and the way they are implemented. To assess the capacity of the laboratories to conduct correctly microbiological analyses, national and international proficiency testing schemes are organized. To set up these inter-laboratory studies (ILS), it is necessary to prepare artificially contaminated samples, which contamination level is sufficiently stable regarding their transportation conditions to the participating laboratories. In this context, we tested several procedures to maintain the concentration of Listeria monocytogenes and coagulase-positive staphylococci in milk samples: freezing temperature and addition of bacteriostatic agents at refrigeration temperatures, such as nystatin, boric acid, sodium azide, the lactoperoxidase system, or a boric acid mixture. Through this study we selected preservation procedures, which could be used to stabilize the contamination level of artificially contaminated milk samples during transportation without preventing the growth of the target bacteria during the analysis and after the initial dilution step. Boric acid mixture and boric acid were found to be effective in stabilizing the contamination level of Staphylococcus aureus in milk samples, whereas freezing, a boric acid mixture, and boric acid were suitable for milk samples containing L. monocytogenes, depending on the samples’ contamination rate. [ABSTRACT FROM AUTHOR]

The European Drinking Water Directive defines reference methods for the enumeration of microbiological parameters in drinking water. The method to be used for Escherichia co/i and coliforms is the membrane filtration technique on Lactose TTC agar with Tergitol 7. Many technical drawbacks of the procedure, as well as its limitations regarding the recent taxonomy of coliforms, make it necessary to evaluate alternative methods. Two alternative assays, a chromogenic media (m-ColiBlu24®) and a defined substrate technology-DST test (Colilert 18/Quanty Tray™) were compared with the ISO standard with attention to the phenotypic characteristic of the isolates. Results showed that the ISO method failed to detect an important percentage of coliforms and E. coil while m-ColiBlu24® and Colilert 18 provided results in a shorter time allowing the simultaneous detection of E. co/i and coliforms with no further confirmation steps. [ABSTRACT FROM AUTHOR]

This report compares the enterococci count on samples obtained with Azide NutriDisk (AND) (sterile, dehydrated culture medium) and Slanetz & Bartley (SB) medium when exposed to a variable in incubation time and temperature. Three experiments were performed to examine the recovery of enterococci on AND and SB media using membrane filtration with respect to: (a) incubation time; (b) incubation temperature; and (c) a combination of the two. Presumptive counts were observed at 37, 41, 46 and 47 °C and at 20, 24, 28 and 48 h. These were compared to AWVVA standard method 9230 C (44 °C, 44 h). Samples were confirmed using Kanamycin Aesculin Azide (KAA) agar. Friedman's ANOVA and Students t-test analysis indicated higher enumeration of enterococci when grown on AND (p = 0.45) than SB (p = <0.001) at all temperatures with a survival threshold at 47 °C. Significant results for AND medium were noted at 20 h (p = 0.021), 24 h (p = 0.278) and 28 h (p = 0.543). The study concluded that the accuracy of the AND medium at a greater time and temperature range provided flexibility in incubator technology making it an appropriate alternative to SB medium for monitoring drinking water using field testing kits in developing countries. [ABSTRACT FROM AUTHOR]

Rapid and reliable identification of Bacillus anthracis is of great importance, especially in the event of suspected deliberate release of anthrax spores. However, the identification of B. anthracis is challenging due to its high similarity to closely related species. Since Amerithrax in 2001, a lot of effort has been made to develop rapid methods for detection and identification of this microorganism with special focus on easy-to-perform rapid tests for first-line responders. This article presents an overview of the evolution of B. anthracis identification methods from the time of the first description of the microorganism until the present day. [ABSTRACT FROM AUTHOR]