Mediterranean springs: Keystone ecosystems and biodiversity refugia threatened by global change.

Mediterranean spring ecosystems are unique habitats at the interface between surface water and groundwater. These ecosystems support a remarkable array of biodiversity and provide important ecological functions and ecosystem services. Spring ecosystems are influenced by abiotic, biotic, and anthropogenic factors such as the lithology of their draining aquifers, their climate, and the land use of their recharge area, all of which affect the water chemistry of the aquifer and the spring discharges. One of the most relevant characteristics of spring ecosystems is the temporal stability of environmental conditions, including physicochemical features of the spring water, across seasons and years. This stability allows a wide range of species to benefit from these ecosystems (particularly during dry periods), fostering an unusually high number of endemic species. However, global change poses important threats to these freshwater ecosystems. Changes in temperature, evapotranspiration, and precipitation patterns can alter the water balance and chemistry of spring water. Eutrophication due to agricultural practices and emergent pollutants, such as pharmaceuticals, personal care products, and pesticides, is also a growing concern for the preservation of spring biodiversity. Here, we provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems. We then describe their ecological value and biodiversity patterns and highlight the main risks these ecosystems face. Moreover, we identify existing knowledge gaps to guide future research in order to fully uncover the hidden biodiversity within these habitats and understand the main drivers that govern them. Finally, we provide a brief summary of recommended actions that should be taken to effectively manage and preserve Mediterranean spring ecosystems for future generations. Even though studies on Mediterranean spring ecosystems are still scarce, our review shows there are sufficient data to conclude that their future viability as functional ecosystems is under severe threat.

Exchange-Striction Driven Ultrafast Nonthermal Lattice Dynamics in NiO.

We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic (AFM) semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce Q-resolved effective temperatures describing the transient lattice. We identify a nonthermal lattice state with preferential displacement of O compared to Ni ions, which occurs within ∼0.3 ps and persists for 25 ps. We associate this with transient changes to the AFM exchange striction-induced lattice distortion, supported by the observation of a transient Q asymmetry of Friedel pairs. Our observation highlights the role of spin-lattice coupling in routes towards ultrafast control of spin order.

Investigating the electronic structure of confined multiexcitons with nonlinear spectroscopies.

Strong confinement in semiconductor quantum dots enables them to host multiple electron-hole pairs or excitons. The excitons in these materials are forced to interact, resulting in quantum-confined multiexcitons (MXs). The MXs are integral to the physics of the electronic properties of these materials and impact their key properties for applications such as gain and light emission. Despite their importance, the electronic structure of MX has yet to be fully characterized. MXs have a complex electronic structure arising from quantum many-body effects, which is challenging for both experiments and theory. Here, we report on the investigation of the electronic structure of MX in colloidal CdSe QDs using time-resolved photoluminescence, state-resolved pump-probe, and two-dimensional spectroscopies. The use of varying excitation energy and intensities enables the observation of many signals from biexcitons and triexcitons. The experiments enable the study of MX structures and dynamics on time scales spanning 6 orders of magnitude and directly reveal dynamics in the biexciton manifold. These results outline the limits of the simple concept of binding energy. The methods of investigations should be applicable to reveal complex many-body physics in other nanomaterials and low-dimensional materials of interest.

Investigating exciton structure and dynamics in colloidal CdSe quantum dots with two-dimensional electronic spectroscopy.

Two-Dimensional Electronic Spectroscopy (2DES) is performed on CdSe colloidal quantum dots. These experiments reveal new observations on exciton structure and dynamics in quantum dots, expanding upon prior transient absorption measurements of excitonics in these systems. The 2DES method enables the separation of line broadening mechanisms, thereby better revealing the excitonic lineshapes and biexcitonic interactions. 2DES enables more information rich spectral probing of coherent phonons and their coupling to excitons. The data show spectral modulations and drifts, with differences based upon whether one monitors the excitation energy (E1) or emission energy (E3). These measurements reveal both homogeneous and inhomogeneous broadenings, as well as static and dynamic line broadening. The longitudinal optical phonon modulates the dynamic absorption spectrum both in energy and linewidth. These experiments enable measurement of hot exciton cooling with improved resolution in energy and time. These 2DES results are consistent with prior excitonic state-resolved transient absorption measurements, albeit with the addition of contributions due to coherent phonons. Finally these 2DES experiments enable disentangling of coupling versus relaxation contributions to the signals, further offering a test of electronic structure theory.

The effect of prenatal lifestyle intervention on weight retention 12 months postpartum: results of the Norwegian Fit for Delivery randomised controlled trial.

OBJECTIVE: To examine the effect of a prenatal lifestyle intervention on postpartum weight retention (PPWR). DESIGN: Randomised controlled trial. SETTING: Healthcare clinics in southern Norway. POPULATION: Healthy, nulliparous women with body mass index ≥19 kg/m2 , age ≥18 years, and singleton pregnancy of ≤20 gestational weeks. METHODS: Women were randomised to intervention (dietary counselling twice by phone and access to twice-weekly exercise groups during pregnancy) or control group (standard prenatal care). Intervention compliance was defined post-factum as attending dietary counselling and ≥14 exercise classes. MAIN OUTCOME MEASURES: PPWR (weight measured postpartum minus self-reported pre-pregnancy weight) and the proportion of women returning to pre-pregnancy weight. RESULTS: Of 606 women randomised, 591 were included in an intention-to-treat analysis of pregnancy outcomes and 391 (64.5%) were analysed 12 months postpartum. Mean PPWR was not significantly different between groups (0.66 kg for intervention versus 1.42 kg for control group, mean difference -0.77 kg, 95% CI -1.81, 0.28; P = 0.149). An increased proportion of intervention participants achieved pre-pregnancy weight (53% versus 43%, OR 1.50, 95% CI 1.003, 1.471; P = 0.045). However, the difference was not statistically significant when we adjusted for missing data (adjusted odds ratio (OR) 2.23, P = 0.067) using logistic mixed-effects models analysis. Women compliant with intervention had significantly lower PPWR than control participants, also after adjusting for potential confounders (adjusted mean diff -1.54 kg, 95% CI -3.02, -0.05; P = 0.039). CONCLUSIONS: The Norwegian Fit for Delivery intervention had little effect on PPWR, although women who were compliant with the intervention demonstrated significantly lower PPWR at 12 months. TWEETABLE ABSTRACT: Norwegian Fit for Delivery RCT: little effect of lifestyle intervention on weight retention 1 year postpartum.

Lifestyle intervention to limit gestational weight gain: the Norwegian Fit for Delivery randomised controlled trial.

OBJECTIVE: To examine whether a lifestyle intervention in pregnancy limits gestational weight gain (GWG) and provides measurable health benefits for mother and newborn. DESIGN: Randomised controlled trial. SETTING: Healthcare clinics of southern Norway. POPULATION: Healthy, non-diabetic, nulliparous women, aged ≥18 years, with a body mass index of ≥19 kg/m2 , and with a singleton pregnancy at ≤20 weeks of gestation. METHODS: Women were randomised to an intervention group (with dietary counselling twice by telephone and access to twice-weekly exercise groups) or to a control group (with standard prenatal care). Participants were measured three times during pregnancy and at delivery, and newborns were measured at delivery. Hospital records were reviewed for outcomes of pregnancy and delivery. Assessors were blinded to group allocation. Analysis was performed by intention to treat, assessing GWG using the Student's t-test and linear mixed models, and comparing proportions using the chi-square test. MAIN OUTCOME MEASURES: GWG, rates of pregnancy complications and operative deliveries, and newborn birthweight. RESULTS: A total of 606 women were randomised. Of these, 591 were analysed, with 296 in the intervention group and 295 in the control group. At term, the mean GWG from pre-pregnancy was 14.4 kg for the intervention group and 15.8 kg for the control group (mean difference 1.3 kg; 95% confidence interval, 95% CI 0.3-2.3 kg; P = 0.009). There was no significant difference between groups in the frequency of pregnancy complications or operative deliveries. The intervention demonstrated no effect on the mean birthweight of term infants, or on the proportion of large newborns. CONCLUSIONS: The Norwegian Fit for Delivery lifestyle intervention in pregnancy had no measurable effect on obstetrical or neonatal outcomes, despite a modest but significant decrease in GWG. TWEETABLE ABSTRACT: Norwegian Fit for Delivery RCT: reduced gestational weight gain, unchanged birthweight and obstetric outcomes.

Vitamin C and E supplementation blunts increases in total lean body mass in elderly men after strength training.

The aim of this study was to investigate the effects of vitamin C and E supplementation on changes in muscle mass (lean mass and muscle thickness) and strength during 12 weeks of strength training in elderly men. Thirty-four elderly males (60-81 years) were randomized to either an antioxidant group (500 mg of vitamin C and 117.5 mg vitamin E before and after training) or a placebo group following the same strength training program (three sessions per week). Body composition was assessed with dual-energy X-ray absorptiometry and muscle thickness by ultrasound imaging. Muscle strength was measured as one-repetition maximum (1RM). Total lean mass increased by 3.9% (95% confidence intervals: 3.0, 5.2) and 1.4% (0, 5.4) in the placebo and antioxidant groups, respectively, revealing larger gains in the placebo group (P = 0.04). Similarly, the thickness of m. rectus femoris increased more in the placebo group [16.2% (12.8, 24.1)] than in the antioxidant group [10.9% (9.8, 13.5); P = 0.01]. Increases of lean mass in trunk and arms, and muscle thickness of elbow flexors, did not differ significantly between groups. With no group differences, 1RM improved in the range of 15-21% (P < 0.001). In conclusion, high-dosage vitamin C and E supplementation blunted certain muscular adaptations to strength training in elderly men.

Musculoskeletal fitness and balance in older individuals (65-85 years) and its association with steps per day: a cross sectional study.

BACKGROUND: There is limited normative, objective data combining musculoskeletal fitness (MSF), balance and physical activity (PA) among older adults. The aims were therefore to; 1) describe MSF and balance in older Norwegian adults focusing on age- and sex-related differences; 2) investigate the associations among MSF, balance and objectively-assessed PA levels. METHODS: This was part of a national multicenter study. Participants (65-85 years) were randomly selected from the national population registry. We used ActiGraph GT1M accelerometers to measure PA. Balance and MSF were assessed using: one leg standing (OLS), handgrip strength (HG), static back extension (SBE), sit and reach (SR), back scratch right, left arm over (BSR, BSL). Univariate analyses of variance were used to assess sex differences within the different MSF and balance tests and for comparisons among multiple age groups. Linear regression analysis was used to investigate how PA (expressed in 1000 steps increments) was associated with MSF and balance. RESULTS: 85 women and 76 men were included. Mean age (standard deviation (SD)) was 73.2 (5.4) years for women and 72.3 (4.8) years for men. The youngest participants (65-69 years) had significantly better mean OLS- and SBE results compared with older participants. Women (65-85 years) had significantly better mean SR, BSR, BSL and SBE results compared with men (65-85 years). Men had significantly better mean HG results compared with women. No sex differences in mean OLS results were observed. A daily increment of 1000 steps was associated with better mean test scores for OLS- and SBE tests (b = 1.88, 95% CI: 0.85 to 2.90 (p ≤ 0.001) and b = 4.63, 95% CI: 1.98 to 7.29 (p = 0.001), respectively). CONCLUSION: The youngest (65-69 years) had better static balance and muscular endurance in trunk extensors compared with older participants. Older women (65-85 years) had better joint flexibility than older men (65-85 years), whereas older men had better handgrip strength than older women. A higher PA level was associated with better static balance and muscular endurance in trunk extensors in older individuals. This study provides important normative data, and further investigation of trunk endurance and static balance as key foci for PA interventions in elderly is warranted.

Gene-PUFA interactions and obesity risk.

Although there are indications for modulatory effects of PUFA on associations between SNP and obesity risk, scientific evidence in human subjects is still scarce. The present analyses investigated interaction effects between SNP in candidate genes for obesity and PUFA in erythrocyte membranes on obesity risk. Within the second Bavarian Food Consumption Survey (cross-sectional, population-based), 568 adults provided blood samples. Fatty acid composition of erythrocyte membranes was analysed by means of GC. Genotyping was performed for twenty-one genes, including cytokines, adipokines, neurotransmitters and transcription factors. In addition, plasma IL-6 concentrations were analysed. For the statistical analysis, a logistic regression model assuming additive genetic effects was chosen. About 20 % of the study participants were classified as obese (BMI ≥ 30 kg/m(2)). Several significant gene-PUFA interactions were found, indicating regulatory effects of PUFA by gene variants of IL-2, IL-6, IL-18, TNF receptor family member 1B and 21, leptin receptor and adiponectin on obesity risk. After stratification by genotype, the strongest effects were found for rs2069779 (IL-2) and all tested PUFA as well as for rs1800795 (IL-6) and linoleic or arachidonic acid. The obesity risk of minor allele carriers significantly decreased with increasing fatty acid content. The genetic PUFA-IL-6 interaction was also reflected in plasma IL-6 concentrations. If replicated in a prospective study with sufficient statistical power, the results would indicate a beneficial effect of high PUFA supply for a substantial proportion of the population with respect to obesity risk.

Depression, comorbidities and the TNF-alpha system.

Depression has frequently been reported to be associated with other physical diseases and changes in the cytokine system. We aimed to investigate associations between a medical history of depression, its comorbidities and cytokine plasma levels in the Bavarian Nutrition Survey II (BVS II) study sample and in patients suffering from an acute depressive episode. The BVS II is a representative study of the Bavarian population aged 13-80years. The disease history of its 1050 participants was assessed through face-to-face interviews. A sub-sample of 568 subjects and 62 additional acutely depressed inpatients of the Max Planck Institute of Psychiatry participated in anthropometric measurements and blood sampling. Tumor necrosis factor-alpha (TNF-alpha) and soluble TNF receptor (sTNF-R) p55 and sTNF-R p75 plasma levels were measured using enzyme-linked immunosorbent assays. A history of depression was associated with a higher incidence of high blood pressure, peptic ulcer, dyslipoproteinemia, osteoporosis, allergic skin rash, atopic eczema and thyroid disease. Within the BVS II sample, participants with a history of depression differed from subjects who had never had depression with regard to sTNF-R p55 and sTNF-R p75 levels even when controlling for age, BMI and smoking status. Acutely depressed inpatients showed even higher levels of sTNF-R p55 and sTNF-R p75 than subjects in the normal population. TNF-alpha levels were also significantly elevated in acutely depressed patients. These results confirm earlier studies regarding the comorbidities of depression and support the hypothesis that activation of the TNF-alpha system may contribute to the development of a depressive disorder.

Preeclampsia and gestational weight gain in the Norwegian Fit for Delivery trial.

OBJECTIVE: Excessive gestational weight gain is linked to risk of preeclampsia, but it is not clear whether the association is causal. The purpose of this paper was to examine gestational weight gain in the Norwegian Fit for Delivery study among women who developed preeclampsia compared to those who did not, and to further explore associations between weight gain and preeclampsia by including data on body composition (bioimpedance) assessed in the last trimester of pregnancy. RESULTS: A total of 550 women were eligible for the study. Women who developed preeclampsia gained more weight than women who did not (difference 3.7 kg, p = 0.004), with a 3.5 kg difference in total body water observed in week 36 (p = 0.040). Adjusted for age, education, pre-pregnancy body mass index (BMI), randomization, and fat mass, a one kg increase in GWG was associated with 1.3 times higher odds of preeclampsia (OR: 1.31, 95% CI 1.15-1.49, p < 0.001). An independent inverse association between fat mass in week 36 and odds of preeclampsia was observed (OR: 0.79, 95% CI 0.68-0.92, p = 0.002). Given the observed difference in total body water, these findings point to excess fluid as the component driving the association between gestational weight gain and preeclampsia in the present study. Trial registration The NFFD trial has the Clinical Trials registration: clinicaltrial.gov NCT0100168.

The discrimination between Rb+ and K+ by Escherichia coli is changed after bacteriophage T7 infection.

Rb+ and K+ have similar chemical properties. They share the uptake systems in Escherichia coli and can replace each other inside the cell. These common features led to experiments in which the radioactive isotope 86Rb was used to trace intracellular K+ fluxes. However, the E. coli pumps discriminate between these two ions and one should thus be cautious using 86Rb+ as a tracer for K+. We now report that T7 infection alters the degree of discrimination in such a way that changes of intracellular Rb+ do not reflect changes of K+. It has been observed that shortly after infection the 86Rb+ level was strongly reduced (Ponta, H., Altendorf, K.-H. and Schweiger, M. (1976) Mol. Gen. Genet. 149, 145-150). In contrast, determination of the K+ content showed no change directly after infection (Kuhn, A., Jütte, H. and Kellenberger, E. (1983) J. Virol. 47, 540-552). The efflux of 86Rb was only evident when Rb+ was used in trace amounts. In media conditions under which intracellular K+ was mainly replaced by Rb+, 86Rb+ efflux was not observed.

Allergic sensitisation and allergic rhinitis are associated with n-3 polyunsaturated fatty acids in the diet and in red blood cell membranes.

OBJECTIVE: Due to inconsistent results based on dietary intake data, unsaturated fatty acids in red blood cell (RBC) membranes and diet were used to investigate their association with allergic sensitisation and allergic rhinitis. DESIGN: Cross-sectional, population-based study. SETTING: Bavarian Nutrition Survey II (2002-03), Germany. SUBJECTS: A total of 568 adult participants, 325 women and 243 men. METHODS: By means of logistic regression models, the relation of fatty acids to (i) allergic sensitisation as defined by means of specific serum immunoglobulin E analysis (CAPSX1 class > or = 2), and (ii) self-reported allergic rhinitis was examined. RESULTS: A high cell membrane level of eicosapentaenoic acid (EPA, 20:5 n-3) was inversely associated with allergic sensitisation, the adjusted odds ratio (OR) and 95% confidence interval (95% CI) were 0.52 (0.30-0.90) for the highest (vs lowest) quartile. A similar effect was observed for allergic rhinitis with an OR (95% CI) of 0.50 (0.24-1.03; P = 0.027 for trend). A higher dietary intake of alpha-linolenic acid (ALA, 18:3 n-3) was associated with a decreased risk of allergic sensitisation and allergic rhinitis with ORs (95% CIs) of 0.51 (0.28-0.93) and 0.43 (0.20-0.93), respectively, in the highest quartiles. No other dietary or cell membrane unsaturated fatty acid was significantly associated with the outcome variables, nor was the n-6/n-3 ratio. The strongest effects were observed among subjects under the age of 40 y. CONCLUSIONS: In this cross-sectional study among adults, a high content of n-3 fatty acids in RBC membranes (EPA) or in the diet (ALA) is associated with a decreased risk of allergic sensitisation and allergic rhinitis.

Potassium induces multiple steroidogenic enzymes in cultured rat zona glomerulosa cells.

The effects of the extracellular potassium concentration on the expression of four steroidogenic cytochromes P-450 (CYP11B2, CYP11B1, CYP11A1, and CYP21A1) in cultured rat adrenal zona glomerulosa cells were studied by Northern blot analysis. At a potassium concentration of 6.4 mM, the CYP11B2 messenger RNA (mRNA) level and aldosterone production were undetectable. Upon increasing the potassium concentration to 18 mM, CYP11B2 mRNA and aldosterone production became measurable and reached a plateau within 4 days. The high potassium concentration also caused distinct increases in the levels of CYP11B1, CYP11A1, and CYP21A1 mRNA, comparable to those induced by ACTH. ACTH did not affect the CYP11B2 mRNA level at the lower potassium concentration. In zona fasciculata cells, CYP11B2 expression was not inducible by potassium; CYP11B1, CYP11A1, and CYP21A1 mRNA levels increased in response to ACTH, but not in response to a high potassium concentration. According to these results, potassium initiates CYP11B2 biosynthesis most likely at the level of transcription or by increasing mRNA stability. Potassium also has a zona glomerulosa-specific inductive effect on three other steroidogenic enzymes.

Some chemical aspects of labeling human fibrinogen with 99m-technetium.

Human fibrinogen was labeled with 99m-Technetium. Tin(II)-chloride in citric acid served as reducing agent for the pertechnetate-ion, eluted from a Mo-Tc-generator. Before adding the fibrinogen, the citric acid was always neutralized with sodium hydrogen carbonate. The influences on the quantity of fibrinogen bound 99m-Tc of the relative concentrations of Sn(II), fibrinogen and sodium hydrogen carbonate, of the reaction time and temperature were tested by thin-layer chromatography. The reaction temperature of 28 degrees C showed an optimum of fibrinogen bound 99m-Tc for the reaction time from 1 and 2 hours. With a reaction time of 30 minutes not enough 99m-Tc was bound to fibrinogen, the doubling of the reaction time from 1 to 2 hours showed only an increase of binding of less than 4%. The concentration of Sn(II) with respect to the fibrinogen concentration showed no influence on the quantity of fibrinogen bound 99m-Tc at low Sn(II)-concentrations. At values higher than 34 times of the fibrinogen concentration a decrease of the quantity of bound 99m-Tc was observed. The concentrations of sodium hydrogen carbonate showed no influence on the quantity of fibrinogen bound 99m-Tc but on the clottability of fibrinogen, the pH of the solution must be approximately 7.5. In 3 parallel and independent experiments under optimized conditions (1 hour at 28 degrees C, molar ratio of Sn(II) : fibrinogen = 8.5, pH = 7.5) 89.97 +/- 0.92 % of 99 m-Tc were bound to fibrinogen. Controls of these results by column chromatography showed a binding of 81.08 +/- 1.47 % of 99m-Tc to fibrinogen. The clottability of fibrinogen tested by the method of Clauss (1) was entirely preserved.

Characterization of coryneform bacteria in piggery wastes.

Coryneform bacteria were found to dominate in the microflora of liquid pig manure. After longterm storage or intensive aeration, the number of these organisms began to decline. At the same time, the production of offensive odour decreased. Treatment with o-phosphoric acid and ammonium persulfate led to a decrease in both the total viable count and in the number of coryneform bacteria. The slight odour reduction is explained by the bactericidal effect of these chemicals. A numerical-taxonomic analysis of 131 coryneform organisms isolated from pig manure showed that the bacteria of the 14 taxa recovered were not closely related to recognized bacterial species. They appeared to represent hitherto undescribed species or variants of known species.

Taxonomic Studies on Arthrobacter nicotianae and Related Taxa: Description of Arthrobacter uratoxydans sp. nov. and Arthrobacter sulfureus sp. nov. and Reclassification of Brevibacterium protophormiae as Arthrobacter protophormiae comb. nov.

DNA homology studies were performed on various strains of Arthrobacter and related organisms with peptidoglycans (mureins) of the A3α and A4α variations. Homology values above 20% show strains with the A4α variation to form a coherent group, which is here designated as the "nicotianae" group of organisms. Members of this group show homology values of lower than 20% with strains of the "globiformis" group (Arthrobacter globiformis and relatives), having a A3α peptidoglycan variation. However, the phylogenetic analysis of one representative of the "nicotianae" group by 16S rRNA cataloguing and the comparison of the data with those of A. globiformis, A. oxydans and A. atrocyaneus reveals a close relationship between members of the "nicotianae" and "globiformis" groups. These data indicate that the genus Arthrobacter contains two nuclei whose members can be distinguished from each other by the peptidoglycan type and the menaquinone composition. Strains forming the "nicotianae" group fell into several subgroups which are separated by DNA homology values of less than 50%, indicating the presence of at least 5 genospecies. The genetic data, supported by results of biochemical and physiological studies, provide sufficient grounds to allot the strain Cory nebacterium liquefaciens ATCC 14929 to Arthrobacter nicotianae, for the reclassification of Brevibacterium protophormiae as Arthrobacter protophormiae comb. nov. and for the description of two new species, Arthrobacter sulfureus sp. nov. and Arthrobacter uratoxydans sp. nov.

Polyphasic identification of wild yeast strains isolated from Greek sourdoughs.

A total of forty-five wild yeast strains were isolated from five traditional Greek wheat sourdoughs. Strains were identified using the classical identification technique along with the sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole cell proteins (SDS-PAGE), Fourier transform-infrared spectroscopy (FT-IR) and the randomly amplified polymorphic DNA-polymerase chain reaction analysis (RAPD-PCR). The latter methods confirmed the classical identification. According to the results obtained, fourteen strains were identified as Saccharomyces cerevisiae strains, twenty-five as Pichia membranaefaciens strains and six as Yarrowia lipolytica.

The yeasts of cheese brines.

A total of 365 yeasts were isolated from the brines of soft, semihard and hard cheeses from different manufacturers. Identification was based on 131 characteristics, primarily employing a method with microtitration plates. Most brines exhibited a characteristic yeast flora. The predominant strains proved to be mainly Debaryomyces hansenii and Candida versatilis. In a few brines Trichosporon beigelii, C. rugosa, C. intermedia, Kluyveromyces marxianus, Saccharomyces sp. and C. tenuis/polymorpha were predominant. Also of importance were C. tropicalis, C. parapsilosis, C. zeylanoides, Issatchenkia orientalis and Geotrichum klebahnii. Not all strains could be clearly identified. Lists of characters are provided for subdividing D. hansenii and T. beigelii. The specificity of the yeast flora of brines is assumed to contribute to the sensory variety of cheeses.

Identification of yeasts and coryneform bacteria from the surface microflora of brick cheeses.

Coryneform bacteria and yeasts of 21 brick cheeses from six German dairies, produced by using undefined ripening cultures, were identified. Arthrobacter nicotianae, Brevibacterium linens, Corynebacterium ammoniagenes, Corynebacterium variabilis and Rhodococcus fascians were found in significant numbers. Out of 148 coryneform isolates 36 could not be identified at the species level. With the exception of a large rennet cheese, the coryneform microflora of rennet and acid cured cheeses were similar, but the cheeses had clearly different yeast populations. Debaryomyces hansenii and Galactomyces geotrichum prevailed in rennet cheeses while Kluyveromyces marxianus and Pichia membranaefaciens were the main species found in acid cured cheese. The dominance of Yarrowia lipolytica probably indicates an improper yeast population, resulting in poor cheese quality. Some of the species identified are potential candidates for designing a defined ripening culture for rennet red smear cheese.