Towards yeast taxogenomics: lessons from novel species descriptions based on complete genome sequences.

In recent years, 'multi-omic' sciences have affected all aspects of fundamental and applied biological research. Yeast taxonomists, though somewhat timidly, have begun to incorporate complete genomic sequences into the description of novel taxa, taking advantage of these powerful data to calculate more reliable genetic distances, construct more robust phylogenies, correlate genotype with phenotype and even reveal cryptic sexual behaviors. However, the use of genomic data in formal yeast species descriptions is far from widespread. The present review examines published examples of genome-based species descriptions of yeasts, highlights relevant bioinformatic approaches, provides recommendations for new users and discusses some of the challenges facing the genome-based systematics of yeasts.

Biotechnological applications of the medicinal plant Pseudobrickellia brasiliensis and its isolated endophytic bacteria.

AIM: This study aimed to isolate Pseudobrickellia brasiliensis endophytic bacteria and evaluate the production of hydrolytic enzymes and antibiotics by these bacterial strains. The study also measured the antibacterial activity of P. brasiliensis. METHODS AND RESULTS: Thirteen endophytic bacteria strains were isolated from stem and leaf fragments of P. brasiliensis. Extracellular enzyme production by the isolated endophytic bacteria was evaluated in an agar plate-based assay. The highest protease production was achieved by Bacillus subtilis P4 in alkaline medium. Antimicrobial activity of endophytic bacteria and P. brasiliensis extracts was investigated using microbroth dilution. An MIC value of 1000 µg ml-1 against Pseudomonas aeruginosa was found for B. subtilis P3, B. subtilis P5, Pseudomonas sp. P8 and Pseudomonas sp. P12. Leaf extract of P. brasiliensis showed the highest antibacterial activity against P. aeruginosa, with an MIC value of 0·781 mg ml-1 . CONCLUSIONS: Pseudobrickellia brasiliensis is a source of bacterial endophytes, which can produce antibacterial compounds and enzymes. This work also demonstrated the antibacterial potential of P. brasiliensis. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that revealed the antibacterial activity of P. brasiliensis and bioactive metabolite production by P. brasiliensis endophytic bacteria.

Effects of cytochalasin E on Paracoccidioides brasiliensis.

AIMS: To determine the effects of cytochalasin E, isolated from the extremophile fungus Aspergillus felis, on the cells of Paracoccidioides brasiliensis Pb18. METHODS AND RESULTS: Cytochalasin E showed a minimal inhibitory concentration of 3·6 µmol l-1 and minimum fungicidal concentration of 7·2 µmol l-1 on P. brasiliensis by in vitro microdilution and IC50 >964·0 µmol l-1 on murine macrophages. Its selectivity index (>263) indicated that this compound has selectivity for fungal cells. Morphological alterations were determined by optical and fluorescence microscopy, as well as scanning and transmission electron microscopy. Cytochalasin E affected P. brasiliensis bud-forming pseudohyphae, cell morphology, cell walls and cell membranes; caused the release of cellular material; and resulted in the production of reactive oxygen species. In murine macrophages, it affected cytoskeletal actin and inhibited phagocytosis. CONCLUSION: Cytochalasin E may be useful as an antifungal prototype against P. brasiliensis and in studies on phagocytosis. SIGNIFICANCE AND IMPACT OF THE STUDY: Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM). Treatment is prolonged to control the clinical manifestations and prevent relapse. The study on the effects of cytochalasin E in P. brasiliensis is important because it can be used as a prototype for new antifungal drugs and consequently, broadens the treatment options for PCM.

Production of bioethanol in sugarcane bagasse hemicellulosic hydrolysate by Scheffersomyces parashehatae, Scheffersomyces illinoinensis and Spathaspora arborariae isolated from Brazilian ecosystems.

AIMS: This study aimed to evaluate new d-xylose-fermenting yeasts from Brazilian ecosystems for the production of second-generation ethanol. METHODS AND RESULTS: d-xylose-fermenting yeasts isolated from rotting wood and wood-boring insects were identified as the species Scheffersomyces parashehatae, Scheffersomyces illinoinensis, Spathaspora arborariae and Wickerhamomyces rabaulensis. Among the yeasts tested, those of Sc. parashehatae exhibited the highest ethanol production when cultivated on complex medium (Yp/set  = 0·437 g g-1 ). Sheffersomyces illinoinensis and Sp. arborariae showed similar ethanol production in this assay (Yp/set up to 0·295 g g-1 ). In contrast, in sugarcane bagasse hemicellulosic hydrolysate, Sc. parashehatae and Sc. illinoinensis exhibited similar ethanol production (Yp/set up to 0·254 g g-1 ), whereas Sp. arborariae showed the lowest results (peak Yp/set  = 0·160 g g-1 ). Wickerhamomyces rabaulensis exhibited a remarkable xylitol production (Yp/sxyl  = 0·681  g g-1 ), but producing low levels of ethanol (Yp/set  = 0·042 g g-1 ). CONCLUSIONS: The novel d-xylose-fermenting yeasts showed promising metabolic characteristics for use in fermentation processes for second-generation ethanol production, highlighting the importance of bioprospecting research of micro-organisms for biotechnological applications. SIGNIFICANCE AND IMPACT OF THE STUDY: This study widens the scope for future researches that may examine the native yeasts presented, as limited studies have investigated these species previously.

The involvement of RUNX2 and SPARC genes in the bacterial chondronecrosis with osteomyelitis in broilers.

Economic losses due to an increase of leg disorders in broilers have become a major concern of the poultry industry. Despite the efforts to reduce skeletal abnormalities in chickens, insufficient progress has been made. Bacterial chondronecrosis with osteomyelitis (BCO) is one of the main disorders that affect bone integrity in broilers. However, the genetic pathways and genes involved in most bone problems, including BCO, remains unclear. In this study, femoral samples from male broilers with 45 days of age affected or not with BCO were used to compare the relative expression with a reverse transcription real time PCR approach of 13 candidate genes: SPP1 (osteopontin), TNFRSF11B (osteoprotegerin), SPARC (osteonectin), CALB1 (calbidin 1), CALM (Calmodulin 2), IBSP (sialoprotein), COL1A2 (collagen, type I, α 2), BMP2 (bone morphogenetic protein 2), BMP3 (bone morphogenetic protein 3), RANKL (κ-B nuclear factor ligand), SMAD1 (SMAD family member 1), LEPR (leptin receptor) and RUNX2 (related transcription factor Runt 2). Differential expression test between affected and non-affected groups was performed using the REST software. The RUNX2 and SPARC genes were downregulated (P<0.05) in the affected group, with reduced expression of fourfold when compared with the non-affected group. This result indicates that the downregulation of RUNX2 and SPARC can contribute to an increased incidence of BCO in broilers.

Gliotoxin production by Aspergillus fumigatus strains from animal environment. Micro-analytical sample treatment combined with a LC-MS/MS method for gliotoxin determination.

In this study, gliotoxin production by Aspergillus fumigatus strains from animal environment is studied. Moreover, a rapid, easy and environment-friendly micro-analytical sample treatment procedure coupled with LC-MS/MS was applied for the determination of gliotoxin from A. fumigatus cultures. The ability of gliotoxin production by 143 strains was assayed in yeast extract sucrose agar, and 1 ml of chloroform was used for toxin extraction without further clean-up. Mean recoveries at two spiking levels (2500 and 7000 ng/g; n = 6) were 100.3 ± 6.6 % relative SD (RSD) and 92.4 ± 3.8 % RSD. Repeatability and within-laboratory reproducibility for different concentration levels of gliotoxin (25 to 1000 ng/ml; n = 12) ranged from 0.3 to 5.4 % RSD and from 3.9 to 12.7 % RSD, respectively. The detection limit of the analytical method was 3.5 ng/g. The ability for gliotoxin production by A. fumigatus revealed that 61.5 % of the strains were able to produce the toxin at levels ranging from LOQ to 3430.5 ng/g. However, all the tested samples had similar percentages of producing strains (81.8 to 86.6 %). The micro-analytical sample treatment coupled with LC-MS/MS detection is a precise and useful methodology for determining gliotoxin from fungal extracts of A. fumigatus and allows working both fast and safely and also reducing the effect on the environment. This toxin plays a critical role in the pathobiology of A. fumigatus, and its presence in animal environments could affect animal health and productivity; in addition, there are risks of contamination for rural workers during handling and storage of animal feedstuffs.

Typing clinical and animal environment Aspergillus fumigatus gliotoxin producer strains isolated from Brazil by PCR-RFLP markers.

UNLABELLED: Aspergillus fumigatus, a well-known human and animal pathogen causing aspergillosis, has been historically identified by morphological and microscopic features. However, recent studies have shown that species identification on the basis of morphology alone is problematic. The aim of this work was to confirm the taxonomic state at specie level of a set of clinical (human and animal) and animal environment A. fumigatus strains identified by morphological criteria applying a PCR-RFLP assay by an in silico and in situ analysis with three restriction enzymes. The A. fumigatus gliotoxin-producing ability was also determined. Previous to the in situ PCR-RFLP analysis, an in silico assay with BccI, MspI and Sau3AI restriction enzymes was carried out. After that, these enzymes were used for in situ assay. All A. fumigatus strains isolated from corn silage, human aspergillosis and bovine mastitis and high per cent of the strains isolated from cereals, animal feedstuff and sorghum silage were able to produce high gliotoxin levels. Also, all these strains identified by morphological criteria as A. fumigatus, regardless of its isolation source, had band patterns according to A. fumigatus sensu stricto by PCR-RFLP markers. SIGNIFICANCE AND IMPACT OF THE STUDY: Aspergillus fumigatus is a well-known human and animal pathogen causing aspergillosis. In this study, clinical (human and animal) and animal environment strains were able to produce high gliotoxin levels and had band profiles according to A. fumigatus sensu stricto by PCR-RFLP markers. The results obtained here suggest that strains involved in human and animal aspergillosis could come from the animal environment in which A. fumigatus is frequently found. Its presence in animal environments could affect animal health and productivity; in addition, there are risks of contamination for rural workers during handling and storage of animal feedstuffs.

Fungal contamination and determination of fumonisins and aflatoxins in commercial feeds intended for ornamental birds in Rio de Janeiro, Brazil.

The purposes of this study were to determine the distribution of total mycobiota, to determine the occurrence of Aspergillus spp., Penicillium spp. and Fusarium spp. and to detect and quantify fumonisin B1 and aflatoxin B1 in birds' feedstuffs. Sixty samples from different commercial feeds were collected. Analysis of the total mycobiota was performed and total fungal counts were expressed as CFU g(-1). The isolation frequency (%) and relative density (%) of fungal genera and species were determined. Mycotoxins determination was carried out using commercial ELISA kits. The 48% of standard, 31% of premium and only 9% of super premium feed samples were found above of recommended limit (1 × 10(4) CFU g(-1)). Aspergillus (82%), Cladosporium (50%) and Penicillium (42%) were the most frequently isolated genera. Aspergillus niger aggregate (35%), Aspergillus fumigatus (28%) and Aspergillus flavus (18%) had the highest relative densities. Contamination with fumonisins was detected in 95% of total samples with levels from 0·92 to 6·68 µg g(-1), and the aflatoxins contamination was found in 40% of total samples with levels between 1·2 and 9·02 µg kg(-1). Feed samples contaminated with fumonisins and aflatoxins are potentially toxic to birds.

Evaluation of Saccharomyces cerevisiae as an antiaflatoxicogenic agent in broiler feedstuffs.

Aflatoxins (AF) are the most important mycotoxins produced by toxigenic strains of various Aspergillus spp. Biological decontamination of mycotoxins using microorganisms is a well-known strategy for the management of mycotoxins in feeds. Saccharomyces cerevisiae strains have been reported to bind aflatoxin B1 (AFB1). The aim of this study was to evaluate the ability of S. cerevisiae CECT 1891 in counteracting the deleterious effects of AFB1 in broiler chicks. Experimental aflatoxicosis was induced in 6-d-old broilers by feeding them 1.2 mg of AFB1/kg of feed for 3 wk, and the yeast strain was administrated in feed (10(10) cells/kg), in the drinking water (5 × 10(9) cells/L), or a combination of both treatments. A total of 160 chicks were randomly divided into 8 treatments (4 repetitions per treatment). Growth performance was measured weekly from d 7 to 28, and serum biochemical parameters, weights, and histopathological examination of livers were determined at d 28. The AFB1 significantly decreased the BW gain, feed intake, and impaired feed conversion rate. Moreover, AFB1 treatment decreased serum protein concentration and increased liver damage. The addition of S. cerevisiae strain to drinking water, to diets contaminated with AFB1, showed a positive protection effect on the relative weight of the liver, histopathology, and biochemical parameters. Furthermore, dietary addition of the yeast strain to drinking water alleviated the negative effects of AFB1 on growth performance parameters. In conclusion, this study suggests that in feed contaminated with AFB1, the use of S. cerevisiae is an alternative method to reduce the adverse effects of aflatoxicosis. Thus, apart from its excellent nutritional value, yeast can also be used as a mycotoxin adsorbent.

Fungi and mycotoxins in silage: an overview.

The present revision shows the early and current knowledge in the field of silage fungi and mycotoxins explaining the relevance of fungi and mycotoxins in silage. The problem does not end in animal disease or production losses as mycotoxins in feed can lead to the presence of their metabolic products in dairy products, which will be eventually affecting human health, mainly infants. Silage is green forage preserved by lactic fermentation under anaerobic conditions. This ecosystem maintains its quality and nutritional value depending on interactions among physical, chemical and biological agents. Forages used for ensilage are naturally in contact with yeasts and filamentous fungi, and the contamination often occurs in the field and can also occur during harvesting, transport, storage. Moreover, postharvest poor management can lead to a rapid spoilage. Studies on fungal contamination of dairy cattle feed have shown how corn silage influences the contamination degree of feed supplied to livestock. Increasing knowledge in this area will help elucidate the influence that this microbiota exerts on production and/or degradation of mycotoxins present in silage. Some of these fungi, although opportunist pathogens, are relevant epidemiologically and represent a high risk of contamination to farm workers who handle them improperly.

In vitro study on the effect of Saccharomyces cerevisiae strains on growth and mycotoxin production by Aspergillus carbonarius and Fusarium graminearum.

The effect of Saccharomyces cerevisiae RC008 and RC016 strains, previously selected based on their aflatoxin B1 mycotoxin binding ability and beneficial properties, against Aspergillus carbonarius and Fusarium graminearum under different interacting environmental conditions was evaluated. In vitro studies on the lag phase, growth rate and ochratoxin A/zearalenone and DON production were carried out under different regimens of a(w) (0.95 and 0.99); pH (4 and 6); temperature (25 and 37 °C) and oxygen availability (normal and reduced). Both yeast strains showed antagonistic activity and decreasing growth rate compared to the control. In general, the RC016 strain showed the greatest inhibitory activity. Except at the interacting condition 0.95 a(W), normal oxygen availability and 37 °C, at both pH values, A. carbonarius and F. graminearum were able to produce large amounts of mycotoxins in vitro. In general, a significant decrease in levels of mycotoxins in comparison with the control was observed. S. cerevisiae RC008 and RC016 could be considered as effective agents to reduce growth and OTA, ZEA and DON production at different interacting environmental conditions, related to those found in stored feedstuff. The beneficial and biocontrol properties of these strains are important in their use as novel additives for the control of mycotoxigenic fungi in stored feedstuffs.

Saccharomyces cerevisiae strains and the reduction of Aspergillus parasiticus growth and aflatoxin B1 production at different interacting environmental conditions, in vitro.

The effect of Saccharomyces cerevisiae RC008 and RC016, previously selected based on their aflatoxin B(1) binding ability and beneficial properties, against Aspergillus parasiticus under different interacting environmental conditions was evaluated. Studies concerning the lag phase, growth rate and aflatoxin B(1) production were carried out in vitro under different regimes of a (w) (0.95 and 0.99), pH (4 and 6), temperature (25 and 37°C), and oxygen availability (normal and reduced). Both yeast strains showed great antagonistic activity at pH 4, decreasing growth rate compared with the control. The RC008 strain showed the greatest inhibitory activity at all assayed conditions. A. parasiticus produced large amounts of AFB(1) in vitro. A significant decrease of AFB(1) levels in comparison with the control were observed with yeast interaction. Differences between control and treatment values ranged from 130 to 5400 ng ml(-1). S. cerevisiae RC008 and RC016 could be considered as effective agents in reducing growth and AFB(1) production at different interacting environmental conditions, related to that found in stored feedstuff. The importance of the present work lies in the search for live strains with both probiotic and biocontrol properties able to prolong the safe storage of feedstuff and exert beneficial properties after animal consumption and which could be included in a novel product for animal feed.

Gliotoxin contamination in and pre- and postfermented corn, sorghum and wet brewer's grains silage in Sao Paulo and Rio de Janeiro State, Brazil.

AIMS: The aim of this study was to determine total fungal counts and the relative density of Aspergillus fumigatus and related species in silage samples intended for bovines before and after fermentation as well as to monitor the natural occurrence of gliotoxin in silage samples (pre- and postfermentation). METHODS AND METHODS: The survey was performed in farms located in São Paulo and Rio de Janeiro States in Brazil. In addition, the ability of A. fumigatus strains and related species strains to produce gliotoxin was also evaluated. A total of 300 samples were taken, immediately after opening of the silo (3-5 months) and during the ensiling period. Fungal counts were done by the surface-spread method. Gliotoxin production ability of isolates and natural contamination were determined by HPLC. RESULTS: All postfermented samples had a total number of moulds exceeding 1 × 10(4) CFU g(-1), with Aspergillus sp. as the most prevalent genus. Frequency of strains, among A. fumigatus and related species, was able to produce gliotoxin was similar in pre- and postfermented samples, except for sorghum, which showed differences between both kinds of samples. The highest toxin levels were produced by strains isolated from postfermented samples. More than 50% of the samples showed gliotoxin contamination levels that exceeded concentrations known to induce immunosuppressive and apoptotic effects in cells. CONCLUSIONS: The present data suggest that care should be taken because gliotoxin contamination in feedstuffs could affect productivity and also present a health risk for herds. SIGNIFICANCE AND IMPACT OF THE STUDY: Gliotoxin was found at quite important concentrations levels in pre- and postfermented substrates and its presence could therefore probably affect the productivity and health of herds. Current conservation and management practices do not avoid contamination with A. fumigatus on silage. Therefore, farm workers should be adequately protected during its handling.

Fungi and Mycotoxins from Pre- and Poststorage Brewer's Grain Intended for Bovine Intensive Rearing.

The aim of the study was to determine the mycobiota and natural levels of mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA), fumonisin B1 (FB1), and deoxynivalenol (DON) present in brewers grains pre- and poststored intended for bovine intensive rearing. Poststored (80%) samples had counts higher than 1 × 10(4) colony-forming units (CFU/g). Cladosporium spp. and Aspergillus spp. were isolated at high frequencies. Aspergillus flavus was the prevalent isolated species. Prestored (70%) and poststored (100%) samples showed AFB1 levels over the recommended limits (20 µ g/Kg), and OTA levels were below the recommended limits (50 µ g/Kg) while pre- and poststored samples did not show FB1 and DON natural contamination levels. The presence of mycotoxins in this substrate indicates the existence of contamination. Regular monitoring of feeds is required in order to prevent chronic and acute toxic syndromes related to this kind of contamination.

Ochratoxin A in wines from 2002 to 2008 harvest marketed in Rio de Janeiro, Brazil.

The occurrence of ochratoxin A (OTA) in wine from 2002 to 2008 harvest, traded in Rio de Janeiro State, was evaluated by analysing 43 national and 37 imported wines from Argentina (32) and Chile (5), adding up to 80 samples in total. OTA determination was performed using immunoaffinity columns and high-performance liquid chromatography. In 80 wine samples analysed, 25 (31.3%) were positive, presenting levels greater than 0.020 ng OTA mL⁻¹. It was not detected in imported wines. Within national wines, 58.1% of the samples were contaminated, with levels ranging from 0.020 to 0.050 ng mL⁻¹. The toxin was detected in 18 (69.2%) of 26 samples analysed of red table wine. Wines from 2008 harvest presented 84.6% of samples contaminated in 13 samples analysed. Despite the levels found in this study, they are below Brazilian tolerance limits. Nevertheless, the presence of OTA as found contributes to the human exposure to this toxin.

Saccharomyces cerevisiae strains retain their viability and aflatoxin B1 binding ability under gastrointestinal conditions and improve ruminal fermentation.

The aim was to evaluate both the ability of yeast strains to survive and bind AFB(1) under ruminant gastrointestinal conditions and the effect of these yeast strains on ruminal fermentation. Yeast viability was studied under simulated gastrointestinal conditions. AFB(1) binding ability was evaluated at different pH values as present in the ruminant gastrointestinal tract. The effect of yeast strains on cellulose digestion and volatile fatty acids production by ruminal bacteria was also evaluated. All yeast strains were able to survive under gastrointestinal conditions and to adsorb AFB(1) at the different pH assayed. The strain RC016 showed the highest binding percentage at the three tested pH. The number of cellulolytic bacteria in ruminal fluid increased in the presence of RC008 and RC016 yeast strains. The concentration of acetate and propionate after ruminal fermentation increased with the addition of RC008 and RC016 strains; this effect was less significant with RC009 strain. Strains RC008 and RC016 are potential probiotic to be included in animal feed: they help to increase fibber digestibility and could reduce AFB(1 )bioavailability in the gastrointestinal tract. Viable S. cerevisiae RC008 and RC016 strains with both probiotic and mycotoxins adsorption properties could be used as feed additives in ruminant feedstuff.

Mycobiota and mycotoxins in malted barley and brewer's spent grain from Argentinean breweries.

AIMS: To evaluate mycobiota and aflatoxins B(1) (AFB(1)), B(2) (AFB(2)), G(1) (AFG(1)), G(2) (AFG(2)) and fumonisin B(1) (FB(1)) contamination in different malted barley types and brands and brewer's grain collected from a major Argentinean brewery. METHODS AND RESULTS: Total fungal counts were performed using the plate count method. Aflatoxin B(1), AFB(2), AFG(1), AFG(2) and Zearalenone (ZEA) analyses were performed by thin-layer chromatography (TLC). Fumonisin B(1) was determined by HPLC. Eighty-three percentage of the malted barley (100% M1, 50% M2 and 100% M3) and 61% of brewer's grain samples had a count >1 × 10(4) CFU g(-1). Yeasts were isolated from all malt and brewer's grain samples. Genera containing some of the most important mycotoxin producer species--Fusarium ssp., Aspergillus ssp., Penicillium ssp. and Alternaria ssp.--were isolated from the analysed samples, along with other environmental saprophytic fungi such as Geotrichum ssp., Mucorales and Cladosporium ssp. All samples were contaminated with 104-145 µg kg(-1) FB(1). Eighteen per cent of brewer's grain samples were contaminated with 19-44.52 µg kg(-1) AFB(1). Aflatoxin B(2), AFG(1), AFG(2) and ZEA were not detected in any of the analysed samples. CONCLUSIONS: Fungal and mycotoxin contamination in malt and brewer's grain is an actual risk for animal and human health. SIGNIFICANCE AND IMPACT OF THE STUDY: This study may be useful for assessing the risk of mycotoxins in Argentinean beers and especially in animal feeds.

Identification of Staphylococcus spp. isolated during the ripening process of a traditional minas cheese / Identificação de Staphylococcus spp. isolados durante o processo de maturação de um queijo-de-minas tradicional

The population dynamics of Staphylococcus spp. was studied during the ripening of Canastra Minas cheese at three farms located in the State of Minas Gerais, Brazil. The presence of coagulase (coa), thermonuclease (nuc), and enterotoxin (sea, seb, sec, and sed) genes was investigated in Staphylococcus strains isolated during the 60-day cheese-ripening period. The presence of the staphylococcal enterotoxins A, C, and D was also investigated in the cheese samples. Cheese samples that were matured for 0, 7, 15, 30, and 45 days presented staphylococci counts from 10³ to 10(8)cfu/g. All isolates considered coagulase-positive by physiological tests had the coa gene. However, no association was observed between the results obtained with biochemical tests and those obtained by PCR using gene-specific primers for coagulase-negative strains. Coagulase and thermonuclease genes occurred simultaneously in 41.3 percent of Staphylococcus spp. tested. None of the investigated Staphylococcus strains expressed enterotoxins SEA, SEB, SEC, and SED. Enterotoxins A, C, and D were not detected in any of the cheese samples.

Estudou-se a dinâmica das populações de Staphylococcus spp. durante a maturação do queijo Canastra, em três fazendas localizadas no estado de Minas Gerais. A presença dos genes que codificam para a produção das enzimas coagulase (coa), termonuclease (nuc) e produção de enterotoxinas (sea, seb, sec e sed), em linhagens de Staphylococcus isoladas durante os 60 dias de maturação do queijo foi analisada. Também foi investigada a presença de enterotoxina estafilocócica A, C e D nas amostras de queijo. As amostras de queijo com 0, 7, 15, 30 e 45 dias de maturação apresentaram contagens de Staphylococcus spp. entre 10³ e 10(8)ufc / g. Todos os isolados coagulase positivo nos testes fisiológicos apresentaram o gene coa. Não foi observada associação entre os resultados obtidos com os testes bioquímicos e aqueles obtidos com a PCR usando iniciadores gene-específicos para linhagens coagulase negativa. Os genes da coagulase e termonuclease ocorreram simultaneamente em 41,3 por cento dos Staphylococcus spp. testados. Nenhum dos isolados de Staphylococcus apresentou os genes que codificam para a produção das enterotoxinas SEA, SEB, SEC ou SED. As enterotoxinas A, C ou D não foram detectadas em nenhuma das amostras de queijo analisadas.

Leveduras no rúmen de caprinos e bovinos de corte criados em pastagem tropicais / Yeasts in the rumen of beef steers and goats raised on tropical pasture

Yeasts suplemented in the rumen have been produced benefic interations in the digestion and in the health of the ruminants. This study aimed to quantify, to isolate and, to identify aerobic fungi and yeasts naturally present in the rumen of goats and cattle raised on tropical pastures of the North of Minas Gerais State, Brazil. Samples of 15mL of ruminal juice from 18 hibrid goats and 31 crossbred Nellore steers were used. The physico-chemical characteristics of the samples were evaluated and mycological culture, quantification, and identification of the aerobic fungi were performed. The results indicated the absence of yeasts in the ruminal fluid of steers. However, theses microorganisms were cultured from ruminal juice for all evaluated goats, at an average concentration of 3.2 x 10VCFU/mL. The species Pichia membranifaciens was the most frequently identified yeast, suggesting its participation in the ruminal microbiot of theses small ruminants.