Nonconventional yeasts and hybrids for low temperature handcrafted sparkling ciders elaboration in Patagonia

Yeasts play a crucial role in transforming apple must into cider. While Saccharomyces cerevisiae (Sc) has been traditionally associated to cider fermentations worldwide, cryotolerant species such as Saccharomyces uvarum (Su) as well as natural S. cerevisiae × S. uvarum (Sc×Su) hybrids have also been detected in ciders fermented at low temperatures. This study aimed to evaluate the ability of two Patagonian cryotolerant yeast strains (Su and Se) and their interspecific hybrids with a Sc to conduct handcrafted apple must fermentations and a second fermentation process (champenoise method). The main chemical parameters and sensory quality of the resulting sparkling beverages was also analysed. Firstly, Sc×Se and Sc×Su hybrids were evaluated in their fermentative features at laboratory scale. Hybrids were compared with their respective parental species evidencing significant differences in the physicochemical and aromatic composition of the obtained base ciders. Both Su parental strain and the hybrid Sc×Se were selected for performing pilot scale fermentations (250 L) using natural (non-sterilized) apple juice at two different temperatures: 20 °C and 13 °C. Sc parental strain was also evaluated for comparative purposes. All base ciders obtained were then subjected to a second fermentation. A high implantation capacity of both Su and the hybrid was evidenced at the lowest evaluated temperature, while commercial Sc strain was not detected at the final fermentation stage, independently from the temperature. All sparkling ciders exhibited distinct physicochemical profiles. Ciders inoculated with commercial Sc (but effectively fermented with local Sc strains) allowed the development of malolactic fermentation (MLF) in processes carried out at both temperatures. Contrarily, no MLF was observed in ciders inoculated with either Su or the hybrid. Sparkling ciders fermented with Su displayed the highest concentrations of 2-phenylethanol and 2-phenylethyl acetate, regardless of the fermentation temperature. Conversely, ciders fermented with the hybrid at 20 °C exhibited the highest concentrations of ethyl octanoate and ethyl decanoate, contributing to floral and fruity notes in the beverage. Sensory analysis conducted with untrained individuals revealed a preference for sparkling ciders produced with the hybrid strain at both 20 °C and 13 °C. The cider fermented at 20 °C exhibited floral notes, sweetness, and a full body, while ciders fermented at 13 °C displayed moderate acidity and a well-balanced profile. Conversely, a trained panel described the cider fermented at 20 °C with Su as a fruity and acidic beverage, whereas the ciders fermented at 13 °C exhibited intense bitterness and acidity. This study highlights the potential of cryotolerant Saccharomyces species and hybrids in the development of new starter cultures for producing artisanal sparkling ciders with distinctive properties.

Differential consumption of malic acid and fructose in apple musts by Pichia kudriavzevii strains

AIMS

To assess the capability of Pichia kudriavzevii strains isolated from wine, cider, and natural environments in North Patagonia to produce ciders with reduced malic acid levels.

METHODS AND RESULTS

Fermentation kinetics and malic acid consumption were assessed in synthetic media and in regional acidic apple musts. All P. kudriavzevii strains degraded malic acid and grew in synthetic media with malic acid as the sole carbon source. Among these strains, those isolated from cider exhibited higher fermentative capacity, mainly due to increased fructose utilization; however, a low capacity to consume sucrose present in the must was also observed for all strains. The NPCC1651 cider strain stood out for its malic acid consumption ability in high-malic acid Granny Smith apple must. Additionally, this strain produced high levels of glycerol as well as acceptable levels of acetic acid. On the other hand, Saccharomyces cerevisiae ÑIF8 reference strain isolated from Patagonian wine completely consumed reducing sugars and sucrose and showed an important capacity for malic acid consumption in apple must fermentations.

CONCLUSIONS

Pichia kudriavzevii NPCC1651 strain isolated from cider evidenced interesting features for the consumption of malic acid and fructose in ciders.

Convergent adaptation of Saccharomyces uvarum to sulfite, an antimicrobial preservative widely used in human-driven fermentations

Different species can find convergent solutions to adapt their genome to the same evolutionary constraints, although functional convergence promoted by chromosomal rearrangements in different species has not previously been found. In this work, we discovered that two domesticated yeast species, Saccharomyces cerevisiae, and Saccharomyces uvarum, acquired chromosomal rearrangements to convergently adapt to the presence of sulfite in fermentation environments. We found two new heterologous chromosomal translocations in fermentative strains of S. uvarum at the SSU1 locus, involved in sulfite resistance, an antimicrobial additive widely used in food production. These are convergent events that share similarities with other SSU1 locus chromosomal translocations previously described in domesticated S. cerevisiae strains. In S. uvarum, the newly described VII^XVI and XI^XVI chromosomal translocations generate an overexpression of the SSU1 gene and confer increased sulfite resistance. This study highlights the relevance of chromosomal rearrangements to promote the adaptation of yeast to anthropic environments.

It is known that genetically distant species can arrive to similar evolutionary solutions during the adaptation to a specific environment, a phenomena known as convergent adaptation, and this frequently occurs after point mutations, gene duplications, or species hybridizations. In this work, we discovered a new example of convergent evolution in the adaptation of two wine fermentation yeast species to the presence of sulfite, an antimicrobial additive widely used in food production. We observed that two species, Saccharomyces cerevisiae and Saccharomyces uvarum, acquired chromosomal rearrangements to convergently adapt to the presence of sulfite in fermentative environments. We describe new chromosomal translocations in S. uvarum strains that generate an overexpression of the SSU1 gene and confer increased sulfite resistance, a similar event that was already described in S. cerevisiae. Overall, this study describes a new case of convergent evolution in which the chromosomal rearrangements have a significant role in the adaptation of yeast to an environment created by humans to produce food.

Evaluation of cryotolerant yeasts for the elaboration of a fermented pear beverage in Patagonia: Physicochemical and sensory attributes

The production of pome fruits as pears and apples, as well as their derived industries, is of great economic importance in North Patagonia. The elaboration of fermented beverages as cider or perry has evidenced a substantial diversification during the last years, with the evaluation of different fruit varieties, yeast starters and technological changes. In this work, two cryotolerant yeasts belonging to the species Saccharomyces uvarum were evaluated at laboratory and pilot scale in sterile and no-sterile pear must. One of the strains was originally isolated from apple chicha (strain NPCC1314) and the other from apple cider (strain NPCC1420) in Patagonia. Both physicochemical and sensory features of the fermented products were evaluated. Both strains were able to successfully complete the fermentations, although strain NPCC1420 showed the better kinetic properties including a faster sugar consumption than the strain NPCC1314. Both strains showed excellent implantation capacity, but the fermented products showed different chemical profiles. The perry fermented with the strain NPCC1314 was characterized by better sensory attributes as assessed by trained panelists and a greater acceptance for untrained public than the same fermented with the strain NPCC1420. The two strains were able to consume sorbitol, both in pear must and in agar-plates supplemented with sorbitol as the sole carbon source. This ability is described for the first time in S. uvarum, at least for the two strains evaluated in this work.

Purification and characterization of Saccharomyces eubayanus killer toxin: Biocontrol effectiveness against wine spoilage yeasts

Microbiological contamination by spoilage yeasts species are frequent during winemaking, and biological control using antagonistic yeasts is considered a more beneficial alternative to conventional synthetic antimicrobials. Saccharomyces eubayanus killer toxin (SeKT) was produced and purified in a synthetic optimized medium. Purification procedure allowed the identification of SeKT as protein with an apparent molecular mass of 70 kDa and activity at physicochemical conditions suitable for winemaking process. Purified SeKT reduced the levels of volatile phenols produced by the spoilage yeasts Brettanomyces bruxellensis, Pichia membranifaciens, Meyerozyma guilliermondii and Pichia manshurica in wine-like medium. The putative mode of action of SeKT on sensitive yeast strains comprises cell wall disruption through β-glucanase and chitinase activities as well as necrotic and apoptotic death in a toxin dose dependent manner. Thus, SeKT appears to be a promising biocontrol agent against spoilage yeasts during wine aging and storing.

Inheritance of winemaking stress factors tolerance in Saccharomyces uvarum/S. eubayanus × S. cerevisiae artificial hybrids

Stress has been defined as any environmental factor that impairs the growth of a living organism. High concentrations of ethanol, sugars and SO₂ as well as temperature variations occurring during winemaking processes are some recognized stress factors that yeasts must overcome in order to avoid stuck or sluggish fermentations. At least two of these factors -sugar and ethanol concentrations- are strongly influenced by the global warming, which become them a worry for the future years in the winemaking industry. One of the most interesting strategies to face this complex situation is the generation of hybrids possessing, in a single yeast strain, a broader range of stress factors tolerance than their parents. In the present study, we evaluated four artificial hybrids generated with S. cerevisiae, S. uvarum and S. eubayanus using a non-GMO-generating method, in their tolerance to a set of winemaking stress factors. Their capacity to overcome specific artificial winemaking situations associated with global warming was also analyzed. All four hybrids were able to grow in a wider temperature range (8-37 °C) than their parents. Hybrids showed intermediate tolerance to higher ethanol, sugar and sulphite concentrations than their parents. Additionally, the hybrids showed an excellent fermentative behaviour in musts containing high fructose concentrations at low temperature as well as under a condition mimicking a stuck fermentation.

Fermentative behaviour and competition capacity of cryotolerant Saccharomyces species in different nitrogen conditions

The selection of yeasts with low nitrogen requirement is a current need in winemaking. In this work, we analysed nitrogen requirements of strains belonging to the cryotolerant species S. uvarum, S. eubayanus and S. kudriavzevii, in order to evaluate their potential for conducting the fermentation of low nitrogen content grape musts. Our result demonstrated that S. eubayanus is the species less influenced by the increasing nitrogen concentrations in both growth and fermentation conditions. Strains showing the best behaviours, S. eubayanus NPCC 1285 and S. uvarum NPCC 1317, were selected to be tested in mixed cultures with S. cerevisiae T73 at different temperatures (12 °C, 20 °C and 28 °C) in synthetic grape must with different nitrogen concentrations (60, 140 and 300 mg/L YAN). The cryotolerant strains dominated the fermentations carried out at 12 °C while S. cerevisiae prevailed at 28 °C independently from the nitrogen concentration. At intermediate temperature, 20 °C, S. eubayanus mono and mixed cultures showed the best fermentative behaviour especially with low and intermediate nitrogen concentration. In summary, cryotolerant Saccharomyces species, particularly S. eubayanus, could be interesting tools to avoid fermentations stucks caused by low nitrogen content in grape musts.

Saccharomyces cerevisiae × Saccharomyces uvarum hybrids generated under different conditions share similar winemaking features

Interspecific hybrids among species in the Saccharomyces genus are frequently detected in anthropic habitats and can also be obtained easily in the laboratory. This occurs because the most important genetic barriers among Saccharomyces species are post-zygotic. Depending on several factors, including the involved strains, the hybridization mechanism and stabilization conditions, hybrids that bear differential genomic constitutions, and hence phenotypic variability, can be obtained. In the present study, Saccharomyces cerevisiae × Saccharomyces uvarum hybrids were constructed using genetically and physiologically different S. uvarum parents at distinct temperatures (13 and 20°C). The effect of those variables on the main oenological features of the wines obtained with these hybrids was evaluated. Hybrids were successfully obtained in all cases. However, genetic stabilization based on successive fermentations in white wine at 13°C was significantly longer than that at 20°C. Our results demonstrated that, irrespective of the S. uvarum parent and temperature used for hybrid generation and stabilization, similar physicochemical and aromatic features were found in wines. The hybrids generated herein were characterized by low ethanol production, high glycerol synthesis and the capacity to grow at low temperature and to produce malic acid with particular aroma profiles. These features make these hybrids useful for the new winemaking industry within the climate change era frame. Copyright © 2017 John Wiley & Sons, Ltd.

Structure and diversity of fishes in a freshwater and coastal subtropical lagoon

This study examined the fish communities of Peri Lagoon in southern Brazil to aid in the development of an effective management plan because the area is under threat from human activities. Sampling of fish fauna, ichthyoplankton and limnological data were compared between sites, differing by habitat type and characteristics such as depth, substratum composition and vegetation type. Results were significantly related to site, with the highest diversity and abundance recorded at shallow vegetated sites. A total of 14 fish species were recorded throughout the lagoon, with the most abundant being Hyphessobrycon luetkenii. Of the 14 species, half were sampled at their larval stage, suggesting a healthy and protected system. Significantly more larvae and eggs were collected during colder months (autumn to winter) and at sites closer to stream flow, possibly owing to increased food sources and habitat protection. This study highlights the importance of Peri Lagoon as a nursery ground for a wide range of fish species, providing essential information for incorporation into the future protection of fish stocks throughout Brazil.

Physiological characterization of Saccharomyces uvarum and Saccharomyces eubayanus from Patagonia and their potential for cidermaking

A diversity of yeast strains belonging to the cryotolerant fermentative species S. uvarum and S. eubayanus have been recovered from natural habitats and traditional fermentations in North Patagonia. The aim of this work was to evaluate the most relevant physiological features in a set of Patagonian strains belonging to S. uvarum and S. eubayanus, in order to analyze their potentiality to be used as starter cultures for cidermaking elaborated at low temperature. We evidenced that S. uvarum strains isolated from natural habitats (Araucaria araucana bark) showed similar physiological features to S. eubayanus strains obtained from the same habitat, and different from S. uvarum strains from fermentative environments (apple chichas). We also confirm the capacity of S. uvarum to produce high glycerol levels, low acetic acid and elevated production of the higher alcohol 2-phenylethanol and 2-phenylethyl acetate and demonstrated similar properties in S. eubayanus. Finally, we evidenced for the first time the antagonistic activity of S. eubayanus and selected three strains (two S. uvarum and one S. eubayanus) bearing the best combination of features to be used as a starter culture in cidermaking.

Prognostic significance of CD44v6, p63, podoplanin and MMP-9 in oral squamous cell carcinomas

OBJECTIVES

To analyse the expression of the CD44v6, p63, podoplanin and MMP-9, and their prognostic significance in patients with oral squamous cell carcinomas (OSCC).

MATERIAL AND METHODS

Immunohistochemistry technique was performed on 60 OSCC for detection of CD44v6, p63, podoplanin and MMP-9 proteins. Extent and intensity of staining were evaluated in tumour cells and were compared with patients' clinical-pathological characteristics and survival.

RESULTS

CD44v6 expression was detected at the membrane of tumour cells of 94% cases. Nuclear expression of p63 protein was present in 96.5%. Podoplanin was observed at the membrane of tumour cells of 94% cases. MMP-9 was found in the cytoplasm of tumour cells in 83.7% cases. A high level of expression (67%-89%) in all four proteins was noted. Podoplanin was associated with the expression of MMP-9 (P = 0.010) and both were associated with lymph node metastasis (P = 0.011 and P = 0.018, respectively). Co-expression of podoplanin/MMP-9 was an adverse independent prognostic factor for cancer-specific survival (P = 0.008) and recurrence-free survival (P = 0.042).

CONCLUSION

Podoplanin and MMP-9 together could contribute to tumour progression and dissemination of OSCC. Their combined overexpression showed an adverse effect on survival, suggesting that they could be regarded as important prognostic biomarkers in OSCC.

Clinicopathologic significance of BubR1 and Mad2 overexpression in oral cancer

OBJECTIVES

BubR1 and Mad2 are central components of the mitotic checkpoint complex that inhibits anaphase onset until all chromosomes are correctly aligned at the metaphase plate. We propose to analyse the combined expression of BubR1 and Mad2 and assess its significance to oral squamous cell carcinoma (OSCC) diagnosis and prognosis.

MATERIALS AND METHODS

BubR1 and Mad2 expression was assessed by real-time PCR in OSCC cell lines and in normal human oral keratinocytes, and by immunohistochemistry in 65 patients with OSCC. The results were compared regarding clinicopathological parameters, proliferative activity and survival.

RESULTS

BubR1 and Mad2 transcripts were overexpressed in OSCC cell lines which also exhibited attenuated spindle assembly checkpoint activity. BubR1 and Mad2 were also overexpressed in patients with OSCC. BubR1 expression was associated with advanced stages and larger tumour size in univariate analysis, and with shorter overall survival both in univariate and multivariate analysis. Mad2 overexpression was associated with that of BubR1 and, importantly, high expression of Mad2 and BubR1 was associated with increased cellular proliferation.

CONCLUSION

Our data propose a role for BubR1 and Mad2 in OSCC cellular proliferation, progression and prognosis.

Molecular and physiological comparison of spoilage wine yeasts

AIMS

Dekkera bruxellensis and Pichia guilliermondii are contaminating yeasts in wine due to the production of phenolic aromas. Although the degradation pathway of cinnamic acids, precursors of these phenolic compounds has been described in D. bruxellensis, no such pathway has been described in P. guilliermondii.

METHODS AND RESULTS

A molecular and physiological characterization of 14 D. bruxellensis and 15 P. guilliermondii phenol-producing strains was carried out. Both p-coumarate decarboxylase (CD) and vinyl reductase (VR) activities, responsible for the production of volatile phenols, were quantified and the production of 4-vinylphenol and 4-ethylphenol were measured. All D. bruxellensis and some P. guilliermondii strains showed the two enzymatic activities, whilst 11 of the 15 strains of this latter species showed only CD activity and did not produce 4-EP in the assay conditions. Furthermore, PCR products obtained with degenerated primers showed a low homology with the sequence of the gene for a phenyl acrylic acid decarboxylase activity described in Saccharomyces cerevisiae.

CONCLUSIONS

D. bruxellensis and P. guilliermondii may share a similar metabolic pathway for the degradation of cinnamic acids.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first work that analyses the CD and VR activities in P. guilliermondii, and the results suggest that within this species, there are differences in the metabolization of cinnamic acids.

Optimization of killer assays for yeast selection protocols

A new optimized semiquantitative yeast killer assay is reported for the first time. The killer activity of 36 yeast isolates belonging to three species, namely, Metschnikowia pulcherrima, Wickerhamomyces anomala and Torulaspora delbrueckii, was tested with a view to potentially using these yeasts as biocontrol agents against the wine spoilage species Pichia guilliermondii and Pichia membranifaciens. The effectiveness of the classical streak-based (qualitative method) and the new semiquantitative techniques was compared. The percentage of yeasts showing killer activity was found to be higher by the semiquantitative technique (60%) than by the qualitative method (45%). In all cases, the addition of 1% NaCl into the medium allowed a better observation of the killer phenomenon. Important differences were observed in the killer capacity of different isolates belonging to a same killer species. The broadest spectrum of action was detected in isolates of W. anomala NPCC 1023 and 1025, and M. pulcherrima NPCC 1009 and 1013. We also brought experimental evidence supporting the importance of the adequate selection of the sensitive isolate to be used in killer evaluation. The new semiquantitative method proposed in this work enables to visualize the relationship between the number of yeasts tested and the growth of the inhibition halo (specific productivity). Hence, this experimental approach could become an interesting tool to be taken into account for killer yeast selection protocols.

Enhanced volatile phenols in wine fermented with Saccharomyces cerevisiae and spoiled with Pichia guilliermondii and Dekkera bruxellensis

AIMS

To investigate whether the presence of Pichia guilliermondii impacts on the production of volatile phenols from mixed wine fermentations with Dekkera bruxellensis and Saccharomyces cerevisiae.

METHODS AND RESULTS

Four inoculation strategies were performed in small-scale fermentations involving P. guilliermondii, D. bruxellensis and S. cerevisiae using Syrah grape juice supplemented with 100 mg l(-1) of p-coumaric acid. High pressure liquid chromatography was used for the quantification or volatile phenols. Significant high levels of 4-ethylphenol and 4-ethylguaicol (720 and 545 microg l(-1), respectively), as well as the highest levels of 4-vinylphenol (>4500 microg l(-1)), were observed when P. guilliermondii species was inoculated from the beginning of the fermentation.

CONCLUSIONS

The metabolic interaction occurring between the high vinylphenol producer species P. guilliermondii and D. bruxellensis exhibiting a high vinylphenol reductase activity resulted in an increased production of volatile phenols in wine.

SIGNIFICANCE AND IMPACT OF THE STUDY

Pichia guilliermondii must be considered a very important spoilage yeast in the wine industry capable of producing large amounts of volatile phenols.

Spoilage yeasts in Patagonian winemaking: molecular and physiological features of Pichia guilliermondii indigenous isolates

Yeasts belonging to the genus Dekkera/Brettanomyces, especially the species Dekkera bruxellensis, have long been associated with the production of volatile phenols responsible for off-flavour in wines. According to recent reports, the species Pichia guilliermondii could also produce these compounds at the initial stages of fermentation. Based on the abundance of P. guilliermondii in Patagonian winemaking, we decided to study the relevance of indigenous isolates belonging to this species as wine spoilage yeast. Twenty-three indigenous isolates obtained from grape surfaces and red wine musts were analyzed in their capacity to produce volatile phenols on grape must. The relationship between molecular Random Amplified Polymorphic DNA (RAPD) and physiological (killer biotype) patterns detected in indigenous populations of P. guilliermondii and volatile phenol production was also evaluated. Different production levels of 4-ethylphenol, 4-vinylguaiacol and 4-ethylguaiacol were detected among the isolates; however, the values were always lower than those produced by the D. bruxellensis reference strain in the same conditions. High levels of 4-vinylphenol were detected among P. guilliermondii indigenous isolates. The combined use of RAPD and killer biotype allowed us to identify the isolates producing the highest volatile phenol levels.

Trophic position of bottom-feeding fish in the Upper Paraná River floodplain

The delta15N composition of bottom-feeding fish (iliophagous = Apareiodon affinis, Cyphocharax nagelii, Prochilodus lineatus, Steindachnerina brevipinna and S. insculpta; detritivorous = Loricariichthys platymetopon and Liposarcus anisitsi; benthophagous = Satanoperca pappaterra and Hoplosternum littorale) and their primary food sources were investigated in the upper Paraná River floodplain during rainy seasons in different environments (lotic and lentic). Two hypotheses were tested: i) that the trophic position and isotopic values of the investigated organisms (fish and food resources) vary spatially; and ii) that trophic position and isotopic compositions differ among iliophagous, detritivorous and benthophagous fish. C4 macrophytes, periphyton and phytoplankton were isotopically different in sites analyzed. Significant isotopic differences occurred in the species of each trophic category. Spatial differences were observed in the isotopic composition of P. lineatus and L. platymetopon, whose values were more enriched in the Paraná River and Pau Véio Lake. Significant spatial differences in trophic position were observed for L. platymetopon and H. littorale, which presented the highest values in the Paraná and Baía rivers, respectively. Trophic positions were significantly different among the species that composed each trophic category. These findings demonstrate that in energy-flow studies in detrital food chains generalizations concerning the grouping of fish into trophic categories and/or habitats should only be carried out after careful investigations of the local/specific trophic dynamics of the organisms.

Diversity and killer behaviour of indigenous yeasts isolated from the fermentation vat surfaces in four Patagonian wineries

The diversity and killer behaviour of the yeast biota associated with surfaces of four Patagonian wineries were analyzed in the present study. These wineries were different in their technological and ecological features. Following liquid enrichment of samples from fermentation vat surfaces yeast isolates were identified by pheno- and genotyping and characterized using killer sensitivity patterns. Out of 92 isolated yeasts, 25% were Saccharomyces cerevisiae; 18% were Kloeckera apiculata and 11% were Pichia anomala; other six species representing a low percentage were also found. A particular biota composed mainly by S. cerevisiae (57%) and P. anomala (37%) was found in the winery located far from the other three wineries. As a whole, the wineries using spontaneous fermentation showed a major percentage of S. cerevisiae and a minor percentage of K. apiculata. The present study showed a pronounced heterogeneity in killer behaviour: killer, 35%, neutral, 25% and sensitive, 40%. In particular, S. cerevisiae isolates showed a higher sensitivity to killer reference yeasts than non-Saccharomyces isolates. On the other hand, most of the non-Saccharomyces yeasts isolated from fermentation vats were resistant to Saccharomyces toxins.

[Rapid identification and susceptibility to killer toxins of yeasts isolated from non-systemic mycoses]

Rapid identification and susceptibility to killer toxins of yeasts isolated from non-systemic mycoses. The use of quick and reliable yeast identification methods, as well as the development of new antifungal agents with more specific targets, will enable a more efficient treatment of mycoses. In the present work, a total of 53 clinical isolates obtained from non-systemic infections in Neuquén Hospitals and an ophthalmologic clinic in Buenos Aires during 2005, were identified by means of a rapid molecular method (ITS1-5.8S ADNr-ITS2 PCR-RFLP). Additionally, the killer susceptibility of the isolates was tested against reference and indigenous killer yeasts on plate tests. Eight yeast species were identified among the clinical isolates: Candida albicans (52%), Candida parapsilosis (17%), Candida tropicalis (10%), Candida krusei (5%), Candida glabrata (4%), Candida guilliermondii (4%), Kluyveromyces lactis (4%) and Saccharomyces cerevisiae (4%). Sixty-nine percent of the isolates corresponding to the predominant species (C. albicans) were related to vaginal infections. On the other hand, 61% of the yeasts associated with ocular infections were identified as C. parapsilosis. Two indigenous killer isolates DVMais5 and HCMeiss5, belonging to Pichia anomala and P. kluyveri respectively, exhibited the broadest killer spectrum against clinical isolates.

A phyllodes tumor of the urinary bladder in a rat

AIM

The aim of this short communication was to describe a case of phyllodes tumor of the urinary bladder discovered in a female Fisher 344 rat that died during an experimental protocol to induce and study urothelial lesions by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN).

METHODOLOGY

From a group of several female rats exposed to BBN via drinking water over the course of 20 weeks, one animal died. At necropsy, a solid mass was identified in the urinary bladder lumen, with a diameter of 0.8 x 0.7 cm. This tumor was processed for histopathological examination and Feulgen coloration.

RESULTS

Microscopically, the mass in the bladder was observed to be a phyllodes tumor. DNA content measured by image analysis of a Feulgen-stained section of the tumor and stroma cells displayed diploid DNA content in both components of the tumor.

CONCLUSION

This is the first reported phyllodes tumor in a rat's urinary bladder. The exact prognosis and histogenesis of phyllodes tumors of the urinary bladder remains to be determined by the accumulation of data from additional cases.

Evaluation of DNA content in preneoplastic changes of mouse urinary bladder induced by N-butyl-N-(4-hydroxybutyl) nitrosamine

Using image cytometry analysis we analysed the deoxyribonucleic acid content of preneoplastic lesions induced in C3H/He female mice. Female mice (n = 30) were given 0.05% BBN in their drinking water for 4, 8 and 12 weeks, and were then euthanized. At the 4th week 90% hyperplasias, 90% dysplasias and 10% papillary tumours developed selectively in the bladder, after 8 weeks mice developed 80% hyperplasias and 80% dysplasias and 12 weeks we identified 70% hyperplasias, 70% dysplasias, 10% papillary tumours and 20% squamous metaplasia. Among the ones who developed simple hyperplasia, 58.3% were diploid and 41.7% were aneuploid. In the dysplasia lesions 29.2% were diploid and 70.8% were aneuploid (p = 0.041). All papillary tumours were aneuploid and all epidermoid metaplasias were diploid. These results suggest that aneuploidization, DNA content alteration of preneoplastic lesions, might be considered as a prognostic factor.

Screening and typing of Patagonian wine yeasts for glycosidase activities

AIMS

The purpose of this study was to select autochthonous glycosidase producer yeasts with potential use in industrial production of Patagonian red wines.

METHODS AND RESULTS

The study was carried out in oenological autochthonous yeasts from Comahue region (Argentinean North Patagonia). A set of screenable yeast phenotypic characteristics indicative of their potential usefulness in more aromatic red wine production was defined and tested in both, Saccharomyces and non-Saccharomyces populations. Twelve isolates showing six different glycosidase phenotypes were selected and they were characterized at species and strain levels using molecular methods. A close correlation between molecular and phenotypic characteristics was observed. Five strains belonging to Candida guilliermondii, C. pulcherrima and Kloeckera apiculata with highest constitutive beta-glucosidase activity levels without anthocyanase activity were discriminated. Some of them also showed constitutive beta-xylosidase and inductive alpha-rhamnosidase activities.

CONCLUSIONS

The extension of the selection of oenological yeast to non-Saccharomyces species provided strains possessing novel and interesting oenological characteristics which could have significant implications in the production of more aromatic young red wine.

SIGNIFICANCE AND IMPACT OF THE STUDY

As these non-Saccharomyces are indigenous to wine, they can be used in mixed starters at the beginning or as pure cultures at the end fermentation to contribute in enhancing the wine nuance that is typical of this specific area.

Saccharomyces cerevisiae wine yeast populations in a cold region in Argentinean Patagonia. A study at different fermentation scales

AIMS

To study the diversity and dynamics of indigenous Saccharomyces wine populations during Malbec spontaneous fermentation, a representative Patagonian red wine, at both industrial and laboratory scale.

METHODS AND RESULTS

Two molecular techniques, including restriction fragment length polymorphism of mitochondrial (mt) DNA and polymorphism of amplified delta interspersed element sequences, were used for characterization of indigenous yeasts at strain level. The mtDNA restriction patterns showed the major discriminative power; however, by combining the two molecular approaches it was possible to distinguish a larger number of strains and, therefore, draw more representative conclusions about yeast diversity. Although a great diversity of wild Saccharomyces cerevisiae strains was observed, only nine represented more than half of the total Saccharomyces yeast biota analysed; five of these were common and took over the Malbec must fermentation in both vinifications.

CONCLUSIONS

Many different indigenous S. cerevisiae strains were identified; nevertheless, the dominant strains in both industrial and laboratory vinification processes were just a few and the same.

SIGNIFICANCE AND IMPACT OF THE STUDY

Small-scale fermentation appears to be a valuable tool in winemaking, one especially helpful in evaluating microbiological aspects of as well as possible interactions between inoculated selected strains and native strains.

Killer behaviour in wild wine yeasts associated with Merlot and Malbec type musts spontaneously fermented from northwestern Patagonia (Argentina)

The occurrence of killer wine yeasts in Comahue Region (Patagonia, Argentina) was studied. Wild wine yeasts were isolated from spontaneously fermenting Merlot and Malbec type musts. Out of 135 isolates analyzed 37% were sensitive to some well characterized killer toxins as K1-K10 and did not show killer activity (sensitive phenotype, S), 21% showed neutral phenotype (N) and 42% demonstrated killer activity (killer phenotype, K). All but two killer strains, identified as Candida pulcherrima and Kluyveromyces marxianus, were Saccharomyces cerevisiae. Additionally, all killer strains were sensitive to some killer reference strains, showing a killer-sensitive phenotype (KS); neither Saccharomyces or non-Saccharomyces wild yeasts were phenotype killer-resistant (KR). The incidence of the killer character varied with respect to fermentation stage and grape variety, increasing throughout fermentation (13-55% to 36-90%). Irrespective of grape must type, the neutral and sensitive yeasts were ever predominant at initial stages of fermentation. All but six neutral strains, identified as Saccharomyces cerevisiae, were Kloeckera apiculata.

[Meningiomas of the cavernous sinus: the surgical resectability and complications]

The optimal management for patients with cavernous sinus meningiomas is to evacuate tumor without causing mortality or morbidity. The records of 16 patients, including 11 women and 5 men ranging in age from 31 to 63 years, underwent surgical treatment for this condition were reviewed. Completeness of tumor resection, cranial nerve morbidity, complications, mortality, the internal carotid artery encasement and outcome were studied. Total removal was achieved in six patients. Of ten patients who underwent subtotal resection there was one death and four were sent to radiotherapy. Morbidity was 24% for cranial nerves controlling extraocular motor function; trigeminal nerve function did not improve after surgical treatment. Symptomatic recurrence occurred in two patients who underwent subtotal tumor resection and in one who underwent complete tumor resection. The average follow-up period was of 26 months. According to our findings, we conclude: 1) the resectability of meningiomas of cavernous sinus depends on the degree of internal carotid artery involvement; 2) total resection of meningiomas confined in cavernous sinus is rare; 3) morbidity of the cranial nerves is significant; 4) subtotal resection is an effective mean to obtain control of the disease.

Seasonal effect on Brazilian propolis antibacterial activity

The behavior of microorganisms towards the antibiotic action of propolis has been widely investigated. Since reports dealing with seasonal effect on propolis activity are not available, this assay was carried out aiming to observe the in vitro antimicrobial activity of propolis, collected during the four seasons, on bacterial strains isolated from human infections. Dilution of ethanolic extract of propolis (EEP) in agar was the method performed, with serial concentrations ranging from 0.4 to 14.0% (% v/v). The behavior of some bacteria was analysed according to the incubation period in medium plus propolis, and the survival curve was plotted. It was verified that the growth of Gram-positive bacteria is inhibited by low propolis concentrations (0.4%) whereas Gram-negative bacteria were less susceptible to this substance, the minimal inhibitory concentration ranging from 4.5 to 8.0%. There was no significant difference with regards to the seasonal effect on the survival curve of Staphylococcus aureus and Escherichia coli; after incubation with propolis, there was an efficient antimicrobial action, mainly towards Gram-positive bacteria.

[Subfrontal approach in sellar and suprasellar lesions]

A variety of mass lesions are placed in and around of the sella turcica. Although their common location these lesions have distinguishing features and different approaches can be selected. There are conventional transcranial and sophisticated skull base approaches. We report our experience with a subfrontal route to the sellar region. Between February 1997 and March 1998, 19 tumors placed around the sella have been treated surgically by this method. Eleven of them were pituitary tumors, 3 were craniopharyngeomas, 2 were meningiomas, and 1 was germinoma. Total removal was achieved in 17 cases. There was not operative mortality. Postoperative complications included twelve cases of unilateral anosmia and four cases of transitory diabetes insipidus. Progressive stroke occurred in one patient. These results stress the importance of the subfrontal approach to reach such lesions in sellar region.

Immunophenotyping by flow cytometry of fine needle aspirates in the diagnosis of lymphoproliferative disorders: A retrospective study

In order to determine the value of flow cytometric (FCM) immunophenotyping of fine-needle aspirates (FNA) in the diagnosis and classification of lymphoproliferative diseases, 61 tissue samples were studied and compared with the cytologic/histological results. In vivo and ex vivo FNA biopsy yielded the material for FCM, which comprised an extensive number of lymphoid cell markers. In all but three cases sufficient cells were collected. Overall, malignancy was diagnosed in 33 cases from a total of 47 (70.2%), and in the remaining cases malignancy was not detected. Eleven cases were correctly diagnosed as reactive processes (11/11). There were no false positive cases of malignancy, as diagnosed by FCM-FNA. The best accuracy was achieved in the low-grade B-cell lymphomas and lymphoblastic lymphoma/leukemia. We conclude that in a significant number of cases, FCM-FNA permits the separation between lymphoid malignancies and reactive processes without false positive results. It was found to be particularly useful in the differential diagnosis of mantle-cell and small-lymphocytic lymphoma and in the identification of lymphoblastic lymphoma/leukemia.

Megaselia scalaris (Diptera: Phoridae) causing myiasis in Crotalus durissus terrificus (Serpentes: Viperidae) in Brazil

We describe a case of myiasis in Crotalus durissus terrificus (Laurenti) caused by Megaselia scalaris (Loew). The snake was found in Anhembi, Sao Paulo, Brazil, with a lesion measuring 25 mm in diameter where the larvae of M. scalaris had penetrated the ribs. The opportunistic behavior of the larvae of M. scalaris is discussed.

[The evaluation of the effect of formol and sodium hypochlorite on the demonstration of Cryptosporidium oocysts in feces by Heine's method]

Cryptosporidium oocysts were searched by Heine's method in stools of nine calves with cryptosporidiosis after stool treatment with two disinfectants, 10% paraformaldehyde solution and 14.5% sodium hypochlorite solution. After 30 minutes exposition to sodium hypochlorite solution oocysts became non refractile and acquired a reddish tinge, making their identification difficult. No morphological alterations occurred in oocysts after paraformaldehyde treatment. We recommend paraformaldehyde at 10% concentration as means of human immunodeficiency virus (HIV) inactivation for routine use in stool examinations and therefore making safer those type of procedures for laboratory personnel, when using Heine's method.

Evaluation of the in vitro susceptibility and emergence of mutants resistant to ciprofloxacin among multidrug resistant clinical isolates

Two hundred and seventy-seven multidrug resistant clinical isolates [K. pneumoniae, (N = 87); E coli, (N = 30); Salmonella typhimurium (N = 100); P. aeruginosa, (N = 30); S. aureus, (N = 30)] from hospitalized patients specimens, were tested in vitro for sensitivity to Ciprofloxacin. Application of the disk diffusion test and determination of the minimal inhibitory concentration by the microdilution method indicated that, almost all isolates were sensitive to the drug. Overall, S. aureus and P. aeruginosa were the less sensitive organisms. Ciprofloxacin-resistant mutants occurred at frequencies of > or = 10(-5)/CFU.

Comparative in vitro activity of three cephalosporins against Staphylococcus aureus isolated from bovine mastitis

This report compares the in vitro activity of three cephalosporins (cephalothin, cefoxitin and ceftriaxone) against 57 Staphylococcus aureus strains isolated from cows with clinical mastitis on the basis of the minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC). The majority of the S aureus strains showed resistance to cefoxitin and ceftriaxone and sensitivity to cephalothin. The highest MICs and MBCs were found for cefoxitin and ceftriaxone. Antimicrobial tolerance (MBC/MIC greater than or equal to 32:1) was observed in relation to cephalothin and ceftriaxone. The data suggest that these cephalosporins may not be effective for the treatment of staphylococcal bovine mastitis. The precise definition of their antimicrobial efficacies requires more detailed in vitro and in vivo studies.

Characteristics of Staphylococcus aureus from subclinical bovine mastitis in Brazil

A total of 127 Staphylococcus aureus strains isolated from milk samples of cows with subclinical bovine mastitis was examined for biotype, phage pattern, in-vitro antibiotic susceptibilities and ability to produce enterotoxins. The majority of the strains showed features consistent with bovine rather than human origin. All strains were sensitive to the antibiotics tested, except penicillin and streptomycin. Enterotoxigenicity was observed in 6 (4.7%) strains and only enterotoxins A and C were produced.

Antimicrobial susceptibilities of Staphylococcus aureus isolated from animal and human sources in Brazil

The susceptibilities of 760 Staphylococcus aureus strains isolated from animal infections (400), human infections (300) and healthy human carriers (60) to seven antibiotics were determined by an agar dilution technique. The isolates from human infections were more resistant to a wider spectrum of antibiotics than were the strains from animal infections and healthy human carriers. Amikacin and gentamicin were the most active drugs against all groups of strains.

[Total coliforms bacteria and coliform of fecal origin in water used for animal drinking]

Foram colhidas 105 amostras de água sendo 44 de mananciais e de 61 bebedouros, a partir das quais foram realizadas as determinações dos NMP (Número Mais Provável) de bactérias coliformes totais e fecais. De acordo com a Portaria GM/0013 de 15 de janeiro de 1976, da Secretaria Especial do Meio Ambiente do Ministério do Interior, os 44 mananciais revelaram-se dentro dos parâmetros estabelecidos. Embora não haja referência com relação a bebedouros, aplicando-se os valores estabelecidos para mananciais, das 61 amostras estudadas, somente 6 (9,8%) não poderiam ser usadas para a dessedentação de animais. Das 105 amostras analisadas, verificou-se que as condições sanitárias revelaram-se não satisfatórias em 6 (5,7%) amostras de bebedouros quanto a coliformes fecais, sendo 3 (2,8%) também com relação a coliformes totais.

[Antimicrobial drugs in poultry nutrition: resistance levels in Escherichia coli]

In a battery experiment, a hundred of day old broiler chicks (Hubbard) divided into ten groups, were fed for eight weeks with 50, 75 or 100mg/Kg of ration of chloramphenicol and tetraciclyne; 40, 80 or 120mg/ 2 liters of drinking water of nitrofurazone. During three months defecated feces from each bird were sampled and analysed at intervals of 15 days for the isolation of Escherichia coli strains which were submitted to the determination of drug resistance. The results showed that utilization of antimicrobial drugs selected a resistant population of Escherichia coli at 300 microgram/ml of chloramphenicol tetraciclyne and 30 microgram/ml of nitrofurazone, during the dietary period. In addition the characterization of the R factor made by conjugation against apropriated recepient strains, demonstrated it's presence in some of the tested strains has only been noted the mobilization of the tetraciclyne marker.

[Isolation of Salmonella from marine shellfish]

The present paper reports the isolation of Salmonella from oysters and clams encountered in the marine waters of Santos and destined to the human consumption. The results obtained showed the characterization of 41 (59,43%) strains of Salmonella arizonae and 28 (40,57%) of Salmonella typhimurium, by its cultural biochemical and serological properties. The drug resistance of Salmonella to several antibiotics was also investigated by determining the minimal inhibitory concentration in serial agar plate dilutions of the therapeutic agents.