Nitrogen source and pH interact and modulate lipase secretion in a non-clinical strain of Candida parapsilosis

Lipases (E.C. 3.1.1.3) are serine-hydrolases, and act on long chain fatty acid ester bonds. They exhibit specific and enantioselective activities, which are desirable for many industrial applications. This study aimed at screening and optimizing the production of lipases by wild yeast strains from a variety of substrates, as well as characterizing the enzyme. An initial selection was made in oxygenated oil-supplemented minimum medium, and the enzymatic activity of the supernatant was tested over p-nitrophenyl palmitate. One-hundred and twenty-four yeast strains from different substrates were tested, and twenty-three showed significantly higher lipolytic activity (p<0.01). One yeast in particular, QU110, showed best lipase production and therefore was selected for the optimization and characterization processes. This yeast exhibits enzyme secretion in initial pH 6.0, with olive oil and tryptone as carbon and nitrogen sources, respectively. There was a strong interaction between nitrogen source and initial pH, and pH 9.0seems to inhibit enzyme secretion. The crude enzyme (cell-free supernatant) shows stability in surfactants and n-hexane, but not in ethanol or methanol. A Response Surface Model was created and optimal enzyme activity conditions were observed at 36°C and pH 8.0. The lipase is appropriate for transesterification reactions, as the enzyme is more stable in strong apolar solvents than moderately apolar ones. Also, secretion by pH was not reported elsewhere, which should be further investigated and contribute for other yeast bioprocesses as well.

Disinfectant activity of the crude hydroalcoholic extract of Achyrocline satureioides (Asteraceae) on Candida spp. isolated in problem-situations of bovine mastitis / Atividade desinfetante do extrato hidroalcoólico bruto de Achyrocline satureioides (Asteraceae) sobre Candida spp. isoladas em situações-problema de mastite bovina

This work was prompted by the phenomenon of yeasts resistance to antifungals, and the need for sanitation products for use in livestock farming in the agroecological model. The objectives were to undertake a qualitative phytochemical analysis of, and assess the antimicrobial/disinfectant action of, the crude hydroalcoholic extract [weight:volume of 5g:100 mL (50 mg mL)] of flowers of Achyrocline satureioides on standard Candida albicans (ATCC 14053) and isolates of cases of bovine mastitis: C. albicans (n = 1) , C. krusei (n = 21) and C. rugosa (n = 9). The test was that of suspension, the lineages in three population densities (PD): 10 5 , 10 4 and 10 3CFU mL, at contact times (CT) of 15 and 30 minutes and from 1 up to 10 hours. Activity results were influenced by the PD and CT variables, with all yeasts inactivated. For example, at the highest PD: the standard strain was inactivated in the reading at 1 hr; of the clinical isolates, C. albicans was inactivated in the reading at 3 hrs; seven isolates of C. krusei at 30 minutes and the other 14 at 1 hr; seven isolates of C. rugosa were inactivated in the reading at 4 hrs, with the others inactivated at 10 hrs. Phytochemicals identified were phenolic compounds, tannins, condensed tannins and flavonoids. The evidence observed suggests the extract’s potential for use on sources of infection in disinfection/antisepsis procedures, or in formulations which serve as a vehicle.

O fenômeno de resistência apresentada por leveduras aos antimicóticos bem como a necessidade de insumos de higiene para uso em sistemas de criação animal baseados no modelo agroecológico motivaram o desenvolvimento deste trabalho. Os objetivos foram realizar a análise fitoquímica qualitativa e avaliar a ação antimicrobiana/desinfetante do extrato hidroalcoólico bruto [peso:volume de 5g:100 mL (50 mg mL)] das flores de Achyrocline satureioides sobre uma Candida albicans padrão (ATCC 14053) e isoladas de casos de mastite bovina: C. albicans (n = 1) , C. krusei (n = 21) e C. rugosa (n = 9). O teste foi o de suspensão, com as linhagens em três densidades populacionais (DP): 10 5 , 10 4 e 10 3 UFC mL, nos tempos de contato (TC) de 15 e 30 minutos e de 1 até 10 horas. Com resultados da atividade influenciados pelas variáveis DP e TC, todas as leveduras foram inativadas. Como exemplo na mais alta DP: a padrão estava inativada na leitura de 1 h; dos isolados clínicos, o de C. albicans inativado na leitura das 3 h; sete isolados de C. krusei estavam inativados aos 30 min e os outros 14 na leitura de 1 h; sete isolados de C. rugosa estavam inativados na leitura das 4 h, os outros até às 10 h. Os fitoquímicos identificados foram compostos fenólicos, taninos, taninos condensados e flavonóides. As evidências observadas sugerem o potencial do extrato para uso sobre as fontes de infecção em procedimentos de desinfecção ou de antissepsia, ou em formulações que lhe sirvam de veículo.

Disinfectant activity of the crude hydroalcoholic extract of Achyrocline satureioides (Asteraceae) on Candida spp. isolated in problem-situations of bovine mastitis / Atividade desinfetante do extrato hidroalcoólico bruto de Achyrocline satureioides (Asteraceae) sobre Candida spp. isoladas em situações-problema de mastite bovina

This work was prompted by the phenomenon of yeasts resistance to antifungals, and the need for sanitation products for use in livestock farming in the agroecological model. The objectives were to undertake a qualitative phytochemical analysis of, and assess the antimicrobial/disinfectant action of, the crude hydroalcoholic extract [weight:volume of 5g:100 mL (50 mg mL)] of flowers of Achyrocline satureioides on standard Candida albicans (ATCC 14053) and isolates of cases of bovine mastitis: C. albicans (n = 1) , C. krusei (n = 21) and C. rugosa (n = 9). The test was that of suspension, the lineages in three population densities (PD): 10 5 , 10 4 and 10 3CFU mL, at contact times (CT) of 15 and 30 minutes and from 1 up to 10 hours. Activity results were influenced by the PD and CT variables, with all yeasts inactivated. For example, at the highest PD: the standard strain was inactivated in the reading at 1 hr; of the clinical isolates, C. albicans was inactivated in the reading at 3 hrs; seven isolates of C. krusei at 30 minutes and the other 14 at 1 hr; seven isolates of C. rugosa were inactivated in the reading at 4 hrs, with the others inactivated at 10 hrs. Phytochemicals identified were phenolic compounds, tannins, condensed tannins and flavonoids. The evidence observed suggests the extracts potential for use on sources of infection in disinfection/antisepsis procedures, or in formulations which serve as a vehicle.(AU)

O fenômeno de resistência apresentada por leveduras aos antimicóticos bem como a necessidade de insumos de higiene para uso em sistemas de criação animal baseados no modelo agroecológico motivaram o desenvolvimento deste trabalho. Os objetivos foram realizar a análise fitoquímica qualitativa e avaliar a ação antimicrobiana/desinfetante do extrato hidroalcoólico bruto [peso:volume de 5g:100 mL (50 mg mL)] das flores de Achyrocline satureioides sobre uma Candida albicans padrão (ATCC 14053) e isoladas de casos de mastite bovina: C. albicans (n = 1) , C. krusei (n = 21) e C. rugosa (n = 9). O teste foi o de suspensão, com as linhagens em três densidades populacionais (DP): 10 5 , 10 4 e 10 3 UFC mL, nos tempos de contato (TC) de 15 e 30 minutos e de 1 até 10 horas. Com resultados da atividade influenciados pelas variáveis DP e TC, todas as leveduras foram inativadas. Como exemplo na mais alta DP: a padrão estava inativada na leitura de 1 h; dos isolados clínicos, o de C. albicans inativado na leitura das 3 h; sete isolados de C. krusei estavam inativados aos 30 min e os outros 14 na leitura de 1 h; sete isolados de C. rugosa estavam inativados na leitura das 4 h, os outros até às 10 h. Os fitoquímicos identificados foram compostos fenólicos, taninos, taninos condensados e flavonóides. As evidências observadas sugerem o potencial do extrato para uso sobre as fontes de infecção em procedimentos de desinfecção ou de antissepsia, ou em formulações que lhe sirvam de veículo.(AU)

High frequency of potentially pathogenic yeast species in goats raw milk and creamed cheese in Southern Brazil

There are few reports concerning isolation, counting and identification of yeasts in goat´s raw milk and derivates. The objective of this study was to evaluate the diversity of yeasts found in raw goat milk and goat creamed cheese collected in a Metropolitan area in Porto Alegre - Brazil. A simplified HMA (Heteroduplex Mobility Assay) of the 26S rDNA D1/D2 region was developed in order to rapidly confirm the identification of the isolates belonging to potentially pathogenic species. Yeasts were isolated from 59% of the samples. Fifty six strains were isolated and identified in the genera Bullera, Candida, Cryptococcus, Debaryomyces, Dekkera, Pichia, Rhodotorula, Sporodiobolus, Trichosporon, Yarrowia and Zygoascus. The average yeast count in raw milk was superior to 2 log UFC.mL-1, while cheese count was superior to 3 log UFC.g-1. Lipolytic activity was present in almost 92% of the isolates, while only 14% had proteolytic activity. Twelve potentially pathogenic ascomycetic isolates were identified by the conventional yeast identification methodology, and correspond to the species Candida parapsilosis, Candida tropicalis and Pichia guilliermondii. All of them had their identities confirmed by the simplified HMA assay. None of the isolates belonging to potentially pathogenic species were resistant to the antifungal agents tested. More studies are necessary to evaluate the real sig

Efeito do congelamento sobre a viabilidade de células leveduriformes

O controle de produtos de origem animal está diretamente associado à sanidade animal e à saúde pública. Na suspeita de mastite, tanto bacteriana quanto micótica, o congelamento de amostras de leite permite aumentar o período de tempo para análise microbiológica, permitindo um correto diagnóstico laboratorial. As leveduras são os principais agentes ambientais envolvidos na mastite micótica. O objetivo do presente trabalho foi verificar se o congelamento afeta a recuperação de leveduras potencialmente presentes no leite. Foram utilizados seis isolados:  Rhodotorula sp. (L1), Geotrichum sp. (L2), Cryptococcus sp. (L3), Candida tropicalis (L4) e Candida albicans (L5), oriundos de leite in natura, e um isolado de C. parapsilosis (ATCC 22019). Após a inoculação experimental, as amostras foram congeladas durante 10 dias, 3, 6 e 8 semanas. O congelamento do leite por períodos superiores a 10 dias causou redução no número de células viáveis. Sugerimos que sejam utilizados períodos mais curtos de congelamento para a análise micológica do leite.

Identification and enzymatic profile of yeasts isolated from artisinal cheese in Southern Brazil

Yeasts may contribute positively to the characteristic taste and flavour development during cheese ripening or cause deterioration of the product. In this study we report the presence of yeasts in 59 samples of artisanal cheeses (43 samples of colonial cheese, 5 of ricotta, 9 of provolone, and 2 of Caccio Cavallo) marketed at stands in the coastal area of Rio Grande do Sul, collected between November 2004 and June 2005. Yeast counts were between 10  4 and 107 UFC/g. One hundred and ten strains were isolated from 30 representative cheese samples. Of these, 97 isolates had ascomycetic affinity, and only 13 were basidiomycetes. The isolates belong to the genera Candida, Debaryomyces, Dekkera, Dipodascus, Galactomyces, Kluyveromyces, Kodamaea, Pichia, Rhodosporidium, Saccharomyces, Schizoblastosporion, Sporidiobolus, Torulaspora, Trichosporon, Yarrowia, and Zygosaccharomyces. The predominant species found were Yarrowia lipolytica, Debaryomyces hansenii, and Candida zeylanoides. More than 56% of the strains were lipolytic, while almost 13% were caseinolytic, and approximately 31% were gelatinolytic. The presence of potentially pathogenic and/or deteriorating yeasts emphasizes the need for a better hygienic control of cheese manufacturing and storage. The ability these microorganisms have to produce proteolytic and lipolytic enzymes enhance the potential risk of cheese deterioration

Qualidade microbiológica de leite cru produzido em cinco municípios do Estado do Rio Grande do Sul, Brasil

O leite pode ser considerado um bom meio de cultura para o crescimento de microrganismos. Estes microrganismos podem contaminar o homem através da ingestão de leite cru, influenciar no tipo de processamento a ser utilizado e interferir na qualidade deste produto e seus derivados. Propriedades leiteiras de cinco municípios no estado do Rio Grande do Sul, Brasil, foram examinadas para determinar a qualidade microbiológica do leite produzido. Foi verificada a presença de coliformes totais, fecais e Salmonella sp. Foi realizada, também, a contagem de bactérias mesófilas, psicrotróficas e de leveduras. Dentre 42 propriedades, 41 apresentaram coliformes totais no leite. Não foi observada diferença significativa entre os tipos de ordenha e os diferentes métodos de resfriamento durante o armazenamento. Somente oito propriedades apresentaram coliformes fecais e confirmação de Escherichia coli, evidenciando falhas nos procedimentos higiênicos durante a ordenha ou armazenamento. Não foi detectada a presença de Salmonella sp. nas amostras, confirmando sua baixa prevalência no leite. Todas as 12 propriedades testadas quanto à presença de bactérias mesófilas e psicrotróficas apresentaram contagens superiores ou igual a 4 log.ufc.mL-1. Foi observada a presença de leveduras em 32 das 34 propriedades testadas com contagens variando entre 1,52 e acima de 4 log.ufc.mL-1. O número elevado de micro

Diversity and enzyme production by yeasts isolated from raw milk in Southern Brazil

Raw milk is generally considered an ideal environment for the growth of many microorganisms because of its nutrient richness. Although there have been numerous reports on the occurrence of yeasts in dairy products in the world, few have attempted to determine the diversity of these microorganisms in samples from raw milk, mainly in Brazil. Thirty six samples were collected from 25 dairy farms located at different districts of Rio Grande do Sul, during a period of 5 months. A total of 80 isolates were obtained and identified according to standard methods. Of these, 63 strains corresponded to true yeasts (51 with ascomycetic and 12 with basidiomycetic affinity), and 17 isolates were recognized as yeast-like strains. Yeast distribution was uneven among the producers analyzed. The most frequent yeasts isolated in this study belong to the genera Kluyveromyces, Rhodotorula, Candida, Geotrichum, and Trichosporon. The high frequency of isolation of Geotrichum and Trichosporon from raw milk is of great concern. Almost 79% of our isolates were lipolytic, while only 6% were proteolytic. Although these microorganisms are not expected to survive the pasteurization/sterilization treatments applied during milk processing, their enzymatic activities may alter milk constituents and affect its quality.

Identification and enzymatic profile of yeasts isolated from artisinal cheese in Southern Brazil

Yeasts may contribute positively to the characteristic taste and flavour development during cheese ripening or cause deterioration of the product. In this study we report the presence of yeasts in 59 samples of artisanal cheeses (43 samples of colonial cheese, 5 of ricotta, 9 of provolone, and 2 of Caccio Cavallo) marketed at stands in the coastal area of Rio Grande do Sul, collected between November 2004 and June 2005. Yeast counts were between 10  4 and 107 UFC/g. One hundred and ten strains were isolated from 30 representative cheese samples. Of these, 97 isolates had ascomycetic affinity, and only 13 were basidiomycetes. The isolates belong to the genera Candida, Debaryomyces, Dekkera, Dipodascus, Galactomyces, Kluyveromyces, Kodamaea, Pichia, Rhodosporidium, Saccharomyces, Schizoblastosporion, Sporidiobolus, Torulaspora, Trichosporon, Yarrowia, and Zygosaccharomyces. The predominant species found were Yarrowia lipolytica, Debaryomyces hansenii, and Candida zeylanoides. More than 56% of the strains were lipolytic, while almost 13% were caseinolytic, and approximately 31% were gelatinolytic. The presence of potentially pathogenic and/or deteriorating yeasts emphasizes the need for a better hygienic control of cheese manufacturing and storage. The ability these microorganisms have to produce proteolytic and lipolytic enzymes enhance the potential risk of cheese deterioration

Diversity and enzyme production by yeasts isolated from raw milk in Southern Brazil

Raw milk is generally considered an ideal environment for the growth of many microorganisms because of its nutrient richness. Although there have been numerous reports on the occurrence of yeasts in dairy products in the world, few have attempted to determine the diversity of these microorganisms in samples from raw milk, mainly in Brazil. Thirty six samples were collected from 25 dairy farms located at different districts of Rio Grande do Sul, during a period of 5 months. A total of 80 isolates were obtained and identified according to standard methods. Of these, 63 strains corresponded to true yeasts (51 with ascomycetic and 12 with basidiomycetic affinity), and 17 isolates were recognized as yeast-like strains. Yeast distribution was uneven among the producers analyzed. The most frequent yeasts isolated in this study belong to the genera Kluyveromyces, Rhodotorula, Candida, Geotrichum, and Trichosporon. The high frequency of isolation of Geotrichum and Trichosporon from raw milk is of great concern. Almost 79% of our isolates were lipolytic, while only 6% were proteolytic. Although these microorganisms are not expected to survive the pasteurization/sterilization treatments applied during milk processing, their enzymatic activities may alter milk constituents and affect its quality.

Diversity and enzyme production by yeasts isolated from raw milk in Southern Brazil

Raw milk is generally considered an ideal environment for the growth of many microorganisms because of its nutrient richness. Although there have been numerous reports on the occurrence of yeasts in dairy products in the world, few have attempted to determine the diversity of these microorganisms in samples from raw milk, mainly in Brazil. Thirty six samples were collected from 25 dairy farms located at different districts of Rio Grande do Sul, during a period of 5 months. A total of 80 isolates were obtained and identified according to standard methods. Of these, 63 strains corresponded to true yeasts (51 with ascomycetic and 12 with basidiomycetic affinity), and 17 isolates were recognized as yeast-like strains. Yeast distribution was uneven among the producers analyzed. The most frequent yeasts isolated in this study belong to the genera Kluyveromyces, Rhodotorula, Candida, Geotrichum, and Trichosporon. The high frequency of isolation of Geotrichum and Trichosporon from raw milk is of great concern. Almost 79% of our isolates were lipolytic, while only 6% were proteolytic. Although these microorganisms are not expected to survive the pasteurization/sterilization treatments applied during milk processing, their enzymatic activities may alter milk constituents and affect its quality.

Identification and enzymatic profile of yeasts isolated from artisinal cheese in Southern Brazil

Yeasts may contribute positively to the characteristic taste and flavour development during cheese ripening or cause deterioration of the product. In this study we report the presence of yeasts in 59 samples of artisanal cheeses (43 samples of colonial cheese, 5 of ricotta, 9 of provolone, and 2 of Caccio Cavallo) marketed at stands in the coastal area of Rio Grande do Sul, collected between November 2004 and June 2005. Yeast counts were between 10  4 and 107 UFC/g. One hundred and ten strains were isolated from 30 representative cheese samples. Of these, 97 isolates had ascomycetic affinity, and only 13 were basidiomycetes. The isolates belong to the genera Candida, Debaryomyces, Dekkera, Dipodascus, Galactomyces, Kluyveromyces, Kodamaea, Pichia, Rhodosporidium, Saccharomyces, Schizoblastosporion, Sporidiobolus, Torulaspora, Trichosporon, Yarrowia, and Zygosaccharomyces. The predominant species found were Yarrowia lipolytica, Debaryomyces hansenii, and Candida zeylanoides. More than 56% of the strains were lipolytic, while almost 13% were caseinolytic, and approximately 31% were gelatinolytic. The presence of potentially pathogenic and/or deteriorating yeasts emphasizes the need for a better hygienic control of cheese manufacturing and storage. The ability these microorganisms have to produce proteolytic and lipolytic enzymes enhance the potential risk of cheese deterioration

Efeito do congelamento sobre a viabilidade de células leveduriformes

O controle de produtos de origem animal está diretamente associado à sanidade animal e à saúde pública. Na suspeita de mastite, tanto bacteriana quanto micótica, o congelamento de amostras de leite permite aumentar o período de tempo para análise microbiológica, permitindo um correto diagnóstico laboratorial. As leveduras são os principais agentes ambientais envolvidos na mastite micótica. O objetivo do presente trabalho foi verificar se o congelamento afeta a recuperação de leveduras potencialmente presentes no leite. Foram utilizados seis isolados:  Rhodotorula sp. (L1), Geotrichum sp. (L2), Cryptococcus sp. (L3), Candida tropicalis (L4) e Candida albicans (L5), oriundos de leite in natura, e um isolado de C. parapsilosis (ATCC 22019). Após a inoculação experimental, as amostras foram congeladas durante 10 dias, 3, 6 e 8 semanas. O congelamento do leite por períodos superiores a 10 dias causou redução no número de células viáveis. Sugerimos que sejam utilizados períodos mais curtos de congelamento para a análise micológica do leite.

High frequency of potentially pathogenic yeast species in goats raw milk and creamed cheese in Southern Brazil

There are few reports concerning isolation, counting and identification of yeasts in goat´s raw milk and derivates. The objective of this study was to evaluate the diversity of yeasts found in raw goat milk and goat creamed cheese collected in a Metropolitan area in Porto Alegre - Brazil. A simplified HMA (Heteroduplex Mobility Assay) of the 26S rDNA D1/D2 region was developed in order to rapidly confirm the identification of the isolates belonging to potentially pathogenic species. Yeasts were isolated from 59% of the samples. Fifty six strains were isolated and identified in the genera Bullera, Candida, Cryptococcus, Debaryomyces, Dekkera, Pichia, Rhodotorula, Sporodiobolus, Trichosporon, Yarrowia and Zygoascus. The average yeast count in raw milk was superior to 2 log UFC.mL-1, while cheese count was superior to 3 log UFC.g-1. Lipolytic activity was present in almost 92% of the isolates, while only 14% had proteolytic activity. Twelve potentially pathogenic ascomycetic isolates were identified by the conventional yeast identification methodology, and correspond to the species Candida parapsilosis, Candida tropicalis and Pichia guilliermondii. All of them had their identities confirmed by the simplified HMA assay. None of the isolates belonging to potentially pathogenic species were resistant to the antifungal agents tested. More studies are necessary to evaluate the real sig

High frequency of potentially pathogenic yeast species in goats raw milk and creamed cheese in Southern Brazil

There are few reports concerning isolation, counting and identification of yeasts in goat´s raw milk and derivates. The objective of this study was to evaluate the diversity of yeasts found in raw goat milk and goat creamed cheese collected in a Metropolitan area in Porto Alegre - Brazil. A simplified HMA (Heteroduplex Mobility Assay) of the 26S rDNA D1/D2 region was developed in order to rapidly confirm the identification of the isolates belonging to potentially pathogenic species. Yeasts were isolated from 59% of the samples. Fifty six strains were isolated and identified in the genera Bullera, Candida, Cryptococcus, Debaryomyces, Dekkera, Pichia, Rhodotorula, Sporodiobolus, Trichosporon, Yarrowia and Zygoascus. The average yeast count in raw milk was superior to 2 log UFC.mL-1, while cheese count was superior to 3 log UFC.g-1. Lipolytic activity was present in almost 92% of the isolates, while only 14% had proteolytic activity. Twelve potentially pathogenic ascomycetic isolates were identified by the conventional yeast identification methodology, and correspond to the species Candida parapsilosis, Candida tropicalis and Pichia guilliermondii. All of them had their identities confirmed by the simplified HMA assay. None of the isolates belonging to potentially pathogenic species were resistant to the antifungal agents tested. More studies are necessary to evaluate the real sig

Efeito do congelamento sobre a viabilidade de células leveduriformes

O controle de produtos de origem animal está diretamente associado à sanidade animal e à saúde pública. Na suspeita de mastite, tanto bacteriana quanto micótica, o congelamento de amostras de leite permite aumentar o período de tempo para análise microbiológica, permitindo um correto diagnóstico laboratorial. As leveduras são os principais agentes ambientais envolvidos na mastite micótica. O objetivo do presente trabalho foi verificar se o congelamento afeta a recuperação de leveduras potencialmente presentes no leite. Foram utilizados seis isolados:  Rhodotorula sp. (L1), Geotrichum sp. (L2), Cryptococcus sp. (L3), Candida tropicalis (L4) e Candida albicans (L5), oriundos de leite in natura, e um isolado de C. parapsilosis (ATCC 22019). Após a inoculação experimental, as amostras foram congeladas durante 10 dias, 3, 6 e 8 semanas. O congelamento do leite por períodos superiores a 10 dias causou redução no número de células viáveis. Sugerimos que sejam utilizados períodos mais curtos de congelamento para a análise micológica do leite.

Efeito do congelamento sobre a viabilidade de células leveduriformes

O controle de produtos de origem animal está diretamente associado à sanidade animal e à saúde pública. Na suspeita de mastite, tanto bacteriana quanto micótica, o congelamento de amostras de leite permite aumentar o período de tempo para análise microbiológica, permitindo um correto diagnóstico laboratorial. As leveduras são os principais agentes ambientais envolvidos na mastite micótica. O objetivo do presente trabalho foi verificar se o congelamento afeta a recuperação de leveduras potencialmente presentes no leite. Foram utilizados seis isolados:  Rhodotorula sp. (L1), Geotrichum sp. (L2), Cryptococcus sp. (L3), Candida tropicalis (L4) e Candida albicans (L5), oriundos de leite in natura, e um isolado de C. parapsilosis (ATCC 22019). Após a inoculação experimental, as amostras foram congeladas durante 10 dias, 3, 6 e 8 semanas. O congelamento do leite por períodos superiores a 10 dias causou redução no número de células viáveis. Sugerimos que sejam utilizados períodos mais curtos de congelamento para a análise micológica do leite.

High frequency of potentially pathogenic yeast species in goats raw milk and creamed cheese in Southern Brazil

There are few reports concerning isolation, counting and identification of yeasts in goat´s raw milk and derivates. The objective of this study was to evaluate the diversity of yeasts found in raw goat milk and goat creamed cheese collected in a Metropolitan area in Porto Alegre - Brazil. A simplified HMA (Heteroduplex Mobility Assay) of the 26S rDNA D1/D2 region was developed in order to rapidly confirm the identification of the isolates belonging to potentially pathogenic species. Yeasts were isolated from 59% of the samples. Fifty six strains were isolated and identified in the genera Bullera, Candida, Cryptococcus, Debaryomyces, Dekkera, Pichia, Rhodotorula, Sporodiobolus, Trichosporon, Yarrowia and Zygoascus. The average yeast count in raw milk was superior to 2 log UFC.mL-1, while cheese count was superior to 3 log UFC.g-1. Lipolytic activity was present in almost 92% of the isolates, while only 14% had proteolytic activity. Twelve potentially pathogenic ascomycetic isolates were identified by the conventional yeast identification methodology, and correspond to the species Candida parapsilosis, Candida tropicalis and Pichia guilliermondii. All of them had their identities confirmed by the simplified HMA assay. None of the isolates belonging to potentially pathogenic species were resistant to the antifungal agents tested. More studies are necessary to evaluate the real sig

Efeito do congelamento sobre a viabilidade de células leveduriformes

O controle de produtos de origem animal está diretamente associado à sanidade animal e à saúde pública. Na suspeita de mastite, tanto bacteriana quanto micótica, o congelamento de amostras de leite permite aumentar o período de tempo para análise microbiológica, permitindo um correto diagnóstico laboratorial. As leveduras são os principais agentes ambientais envolvidos na mastite micótica. O objetivo do presente trabalho foi verificar se o congelamento afeta a recuperação de leveduras potencialmente presentes no leite. Foram utilizados seis isolados:  Rhodotorula sp. (L1), Geotrichum sp. (L2), Cryptococcus sp. (L3), Candida tropicalis (L4) e Candida albicans (L5), oriundos de leite in natura, e um isolado de C. parapsilosis (ATCC 22019). Após a inoculação experimental, as amostras foram congeladas durante 10 dias, 3, 6 e 8 semanas. O congelamento do leite por períodos superiores a 10 dias causou redução no número de células viáveis. Sugerimos que sejam utilizados períodos mais curtos de congelamento para a análise micológica do leite.

High frequency of potentially pathogenic yeast species in goats raw milk and creamed cheese in Southern Brazil

There are few reports concerning isolation, counting and identification of yeasts in goat´s raw milk and derivates. The objective of this study was to evaluate the diversity of yeasts found in raw goat milk and goat creamed cheese collected in a Metropolitan area in Porto Alegre - Brazil. A simplified HMA (Heteroduplex Mobility Assay) of the 26S rDNA D1/D2 region was developed in order to rapidly confirm the identification of the isolates belonging to potentially pathogenic species. Yeasts were isolated from 59% of the samples. Fifty six strains were isolated and identified in the genera Bullera, Candida, Cryptococcus, Debaryomyces, Dekkera, Pichia, Rhodotorula, Sporodiobolus, Trichosporon, Yarrowia and Zygoascus. The average yeast count in raw milk was superior to 2 log UFC.mL-1, while cheese count was superior to 3 log UFC.g-1. Lipolytic activity was present in almost 92% of the isolates, while only 14% had proteolytic activity. Twelve potentially pathogenic ascomycetic isolates were identified by the conventional yeast identification methodology, and correspond to the species Candida parapsilosis, Candida tropicalis and Pichia guilliermondii. All of them had their identities confirmed by the simplified HMA assay. None of the isolates belonging to potentially pathogenic species were resistant to the antifungal agents tested. More studies are necessary to evaluate the real sig