Commercial and non-commercial pectinase and cellulase on the enzymatic hydrolysis efficacy of rice husk and Tifton 85 hay

The aim of this study was to evaluate the action of commercial and non-commercial cellulase and pectinase on rice husk and Tifton 85 hay hydrolyses. The hydrolysis kinetics of the substrates with commercial cellulase and pectinase were evaluated and the hydrolysis at different temperature and agitation conditions was maximized using experimental design. The combined use of commercial and non-commercial enzymes under optimized conditions was evaluated. The pre-treatment of the residues was also investigated by milling and different concentrations of NaOH. Finally, the effect of the hydrolysis on the bromatological composition of the residues was evaluated. The best hydrolysis times of rice husk and Tifton 85 hay were 10 and 12h for commercial cellulase, 12 and 14h for noncommercial cellulase, 10 and 14h for commercial pectinase and 16 and 20h for non-commercial pectinase, respectively. The highest hydrolysis values were obtained using commercial cellulase with 1:50 (w:v enzyme:water) dilution rate, at 45ºC and 300 rpm agitation for both substrates, reaching 20.6% maximum percentage for Tifton 85 hay and 11.6% for rice husk. The combined use of commercial enzymes did not increase hydrolysis percentage. The pre-treatment using 7.5% NaOH and 0.5 mm grain size significantly increased the rice husk and Tifton 85 hay hydrolyses (60-80%), either using commercial cellulase or pectinase enzymes. The use of non-commercial enzymes provided 18-30% hydrolysis obtained from commercial ones. Bromatological analyzes indicated a reduction in neutral detergent fiber and acid detergent fiber content for rice husk and Tifton 85 hay when using pectinases and commercial cellulases.

Commercial and non-commercial pectinase and cellulase on the enzymatic hydrolysis efficacy of rice husk and Tifton 85 hay

The aim of this study was to evaluate the action of commercial and non-commercial cellulase and pectinase on rice husk and Tifton 85 hay hydrolyses. The hydrolysis kinetics of the substrates with commercial cellulase and pectinase were evaluated and the hydrolysis at different temperature and agitation conditions was maximized using experimental design. The combined use of commercial and non-commercial enzymes under optimized conditions was evaluated. The pre-treatment of the residues was also investigated by milling and different concentrations of NaOH. Finally, the effect of the hydrolysis on the bromatological composition of the residues was evaluated. The best hydrolysis times of rice husk and Tifton 85 hay were 10 and 12h for commercial cellulase, 12 and 14h for noncommercial cellulase, 10 and 14h for commercial pectinase and 16 and 20h for non-commercial pectinase, respectively. The highest hydrolysis values were obtained using commercial cellulase with 1:50 (w:v enzyme:water) dilution rate, at 45ºC and 300 rpm agitation for both substrates, reaching 20.6% maximum percentage for Tifton 85 hay and 11.6% for rice husk. The combined use of commercial enzymes did not increase hydrolysis percentage. The pre-treatment using 7.5% NaOH and 0.5 mm grain size significantly increased the rice husk and Tifton 85 hay hydrolyses (60-80%), either using commercial cellulase or pectinase enzymes. The use of non-commercial enzymes provided 18-30% hydrolysis obtained from commercial ones. Bromatological analyzes indicated a reduction in neutral detergent fiber and acid detergent fiber content for rice husk and Tifton 85 hay when using pectinases and commercial cellulases.(AU)

Effect of dietary fiber concentrates on growth performance, gut morphology and hepatic metabolic intermediates in jundiá (Rhamdia quelen) / Efeito de concentrados de fibra alimentar sobre o desempenho de crescimento, morfologia intestinal e intermediários metabólicos hepáticos de jundiás (Rhamdia quelen)

A study was conducted to investigate the effect of Dietary Fiber Concentrates (DFCs) on growth performance, gut morphology, and hepatic metabolic intermediates in jundiá (Rhamdia quelen). At the end of the trial, growth and intestinal villus height was significantly (P< 0.05) higher in fish fed diets supplemented with DFCs. However, the animals in commercial prebiotic group showed higher values for this variable compared to the other treatments. Regarding the thickness of the epithelium bowel, it was greater in the Control group compared to animals supplemented with ß-glucan+mannan. Likewise, treatment with commercial prebiotic showed higher values of epithelium bowel compared to the DFCs. The fish supplemented with DFCs, had higher glycogen storage compared to the control group. These results indicate that DFCs can be considered as a beneficial dietary supplement for improving growth performance, gut morphology, and hepatic metabolic intermediates of jundiá.(AU)

O presente estudo foi conduzido para investigar o efeito de concentrados de fibras alimentares (CFAs) sobre o desempenho de crescimento, a morfologia intestinal e os parâmetros intermediários metabólicos hepáticos de jundiás (Rhamdia quelen). No final do experimento, o crescimento e a altura das vilosidades intestinais foram significativamente (P<0,05) maiores em peixes alimentados com dietas suplementadas com CFAs. No entanto, os animais suplementados com prebiótico comercial apresentaram valores mais elevados para essa variável em comparação com os outros tratamentos. Em relação à espessura do epitélio intestinal, esta foi maior nos animais do grupo controle em comparação com os animais suplementados com ß-glucano + manano. Da mesma forma, os peixes suplementados com prebiótico comercial apresentaram valores mais elevados do epitélio intestinal em comparação com os peixes suplementados com CFAs. Os peixes suplementados com CFAs obtiveram maior armazenamento de glicogênio em relação ao grupo controle. Esses resultados indicam que os CFAs podem ser utilizados como um suplemento alimentar benéfico para melhorar o desempenho do crescimento, a morfologia intestinal e os intermediários metabólicos hepáticos do jundiá.(AU)

Effect of dietary fiber concentrates on growth performance, gut morphology and hepatic metabolic intermediates in jundiá (Rhamdia quelen) / Efeito de concentrados de fibra alimentar sobre o desempenho de crescimento, morfologia intestinal e intermediários metabólicos hepáticos de jundiás (Rhamdia quelen)

A study was conducted to investigate the effect of Dietary Fiber Concentrates (DFCs) on growth performance, gut morphology, and hepatic metabolic intermediates in jundiá (Rhamdia quelen). At the end of the trial, growth and intestinal villus height was significantly (P< 0.05) higher in fish fed diets supplemented with DFCs. However, the animals in commercial prebiotic group showed higher values for this variable compared to the other treatments. Regarding the thickness of the epithelium bowel, it was greater in the Control group compared to animals supplemented with ß-glucan+mannan. Likewise, treatment with commercial prebiotic showed higher values of epithelium bowel compared to the DFCs. The fish supplemented with DFCs, had higher glycogen storage compared to the control group. These results indicate that DFCs can be considered as a beneficial dietary supplement for improving growth performance, gut morphology, and hepatic metabolic intermediates of jundiá.(AU)

O presente estudo foi conduzido para investigar o efeito de concentrados de fibras alimentares (CFAs) sobre o desempenho de crescimento, a morfologia intestinal e os parâmetros intermediários metabólicos hepáticos de jundiás (Rhamdia quelen). No final do experimento, o crescimento e a altura das vilosidades intestinais foram significativamente (P<0,05) maiores em peixes alimentados com dietas suplementadas com CFAs. No entanto, os animais suplementados com prebiótico comercial apresentaram valores mais elevados para essa variável em comparação com os outros tratamentos. Em relação à espessura do epitélio intestinal, esta foi maior nos animais do grupo controle em comparação com os animais suplementados com ß-glucano + manano. Da mesma forma, os peixes suplementados com prebiótico comercial apresentaram valores mais elevados do epitélio intestinal em comparação com os peixes suplementados com CFAs. Os peixes suplementados com CFAs obtiveram maior armazenamento de glicogênio em relação ao grupo controle. Esses resultados indicam que os CFAs podem ser utilizados como um suplemento alimentar benéfico para melhorar o desempenho do crescimento, a morfologia intestinal e os intermediários metabólicos hepáticos do jundiá.(AU)

Detection of manganese peroxidase and other exoenzymes in four isolates of Geastrum (Geastrales) in pure culture.

Knowledge regarding the enzymatic machinery of fungi is decisive to understand their ecological role. The species of the genus Geastrum are known to grow extremely slowly in pure culture, which makes it difficult to evaluate physiological parameters such as enzyme activity. Qualitative assays were performed on isolates of four species of this genus, showing evidence of laccase, cellulase, pectinase, amylase and lipase activity and suggesting that a wide range of carbon sources can be exploited by these species. For the first time in this genus, quantitative assays verified manganese peroxidase activity (up to 0.6mU/g) in 30-day old cultures, as well as laccase, ß-glycosidase and ß-xylosidase activities.

Clonagem e análise da expressão de genes de proteínas de mamão papaia com atividade inibitória sobre poligalacturonases fúngicas / Cloning and expression analysis of papaya genes encoding proteins with inhibitory activity against fungal polygalacturonases

As proteínas inibidoras de poligalacturonases (PGIPs) presentes na parede celular são capazes de limitar o potencial destrutivo da poligalacturonase (PG) fúngica e, assim, constituem um tipo importante dentre os diversos sistemas de defesa do tecido vegetal frente à infecção fúngica. No mamão, o ataque fitopatogênico é o principal causador de danos pós-colheita, e sua alta susceptibilidade pode estar relacionada com a baixa eficácia ou pouca abundância dos meios de defesa anti-fitopatogênica. Uma vez que isso pode estar relacionado com as PGIPs e nada se conhece sobre o papel dessas proteínas nesse fruto, o objetivo do trabalho foi clonar os genes das PGIPs de mamoeiro e definir seu padrão de expressão em diferentes órgãos e tecidos e ao longo do amadurecimento. Para tanto, foram identificadas no genoma do mamoeiro, a partir de critérios que definem a identidade de uma PGIP, duas prováveis sequências dentre 13 candidatas iniciais. Ambas foram clonadas a partir das sequências genômicas e de cDNA, sequenciadas e sua identidade confirmada, sendo denominadas Cppgip4 e Cppgip6. As análises de expressão relativa em diversos tecidos e idades fisiológicas do mamoeiro demonstraram que os dois genes apresentaram diminuição da expressão com o desenvolvimento dos frutos, sendo que com a polpa apresentou redução dos níveis de expressão relativa de Cppgip4 em até 18 vezes dos 30 dias pós-antese (DPA) ao 9 dias pós-colheita (DPC). Na casca também houve redução significativa da expressão com o desenvolvimento. Para a expressão absoluta, nos frutos, sementes, caules, raízes e folhas, o número de cópias de ambos os transcritos decresceu com o desenvolvimento, sendo cerca de cem mil vezes mais abundante para Cppgip6 que para Cppgip4. As tentativas de expressão de proteínas recombinantes em Pichia pastoris não geraram resultado positivo, provavelmente em virtude das condições ideais de indução ainda não terem sido estabelecidas corretamente para o ensaio. A atividade de PGIPs extraídas diretamente do tecido foi medida por análise de difusão em ágar empregando pectinase de Aspergillus niger e revelou uma tendência à diminuição da porcentagem de inibição à medida que os frutos se desenvolveram, em concordância com os resultados da análise por qPCR. O conjunto de resultados sugere que a expressão varia com o estádio de desenvolvimento do fruto e é tecido-específica, possivelmente em resposta à diferente susceptibilidade dos tecidos ao ataque fitopatogênico, indicando que menores níveis de transcritos e atividade no amadurecimento, período de maior susceptibilidade, poderiam sinalizar para a regulação do processo degradativo marcando o início da senescência

Polygalacturonase inhibiting proteins (PGIPs) present in plant cell walls are able to inhibit the destructive action of fungal polygalacturonase (PG). In this way, they constitute an important type of plant defense system against fungal infections. In papaya fruit, the pathogenic attack is the main cause of post harvesting loss, and its high susceptibility may be related to the low efficiency or low abundance of anti-phytopathogenic defense. Since this fact could be related to PGIPs expression and little is known about the response of these proteins in the fruit, the aim of the present work was to clone the genes of PGIPs papaya fruit and set their expression pattern in different organs and tissues throughout fruit ripening. Thus, two probable PGIP sequences among 13 initial candidates were identified in the papaya genome by using specific criteria. Both sequences were cloned from cDNA and genomic samples, sequenced and confirmed its identity, and then being named Cppgip4 and Cppgip6. Analysis of relative expression in various tissues at different physiological stages demonstrated that both genes were down regulated during fruit development. The relative expression levels of Cppgip4 in papaya pulp was reduced by 18 times from the 30 days post-anthesis (DPA) to the 9 days post-harvest (DPH). Similarly, gene expression in papaya peel was significant down regulated during fruit development. Absolute expression analysis revealed gene expressions in the fruit pulp, seed, stem, root and leaf were also down regulated within development. Moreover, Cppgip6 gene expression was a hundred thousand times more abundant than Cppgip4. The recombinant protein expression in Pichia pastoris did not result positive, probably because of the ideal conditions of induction have not been properly established the yet. The activity of PGIPs extracted directly from the tissue was measured by the agar diffusion assay using pectinase from Aspergillus niger and showed decrease of inhibition during fruit developed in accordance with the results of the qPCR analysis. Based on the results it is possible to suggest the expression of these genes varies temporally with the developmental stage of the fruit and is tissue-specific, possibly in response to the different susceptibility of tissues to pathogenic attack. In addition, the lowest levels of PGIP expression were achieved at the fruit ripening, when the susceptibility to fungal infection is high and could signal for regulating the degradation process characterized by the onset of senescence

Richness of endophytic fungi isolated from Opuntia ficus-indica Mill. (Cactaceae) and preliminary screening for enzyme production.

Opuntia ficus-indica Mill. (forage cactus) is farmed with relative success in the semi-arid region of the Brazilian northeast for commercial purposes, particularly as forage and food. Endophytic microorganisms are those that can be isolated inside plant tissues and can be a new source to production of enzymes with different potentialities. The objective of this study was to describe the richness of endophytic fungi from O. ficus-indica and to detect the capacity of these species to produce extracellular hydrolytic enzymes. Forty-four endophytic fungi species were isolated. Among them, the most commonly found were Cladosporium cladosporioides (20.43%) and C. sphaerospermum (15.99%). Acremonium terricola, Monodictys castaneae, Penicillium glandicola, Phoma tropica and Tetraploa aristata are being reported for the first time as endophytic fungi for Brazil. The majority of isolated fungi exhibited enzymatic potential. Aspergillus japonicus and P. glandicola presented pectinolytic activity. Xylaria sp. was the most important among the other 14 species with positive cellulase activity. All 24 isolates analysed were xylanase-positive. Protease was best produced by isolate PF103. The results indicate that there is a significant richness of endophytic fungi in O. ficus-indica, and that these isolates indicate promising potential for deployment in biotechnological processes involving production of pectinases, cellulases, xylanases and proteases.

Constitutive and inducible pectinolytic enzymes from Aspergillus flavipes FP-500 and their modulation by pH and carbon source / Enzimas pectinolíticas constitutivas e indutíveis de Aspergillus flavipes FP-500 e sua modulação pelo pH e fonte de carbono

Growth and enzymes production by Aspergillus flavipes FP-500 were evaluated on pectin, polygalacturonic acid, galacturonic acid, arabinose, rhamnose, xylose, glycerol and glucose at different initial pH values. We found that the strain produced exopectinases, endopectinases and pectin lyases. Exopectinases and pectin lyase were found to be produced at basal levels as constitutive enzymes and their production was modulated by the available carbon source and pH of culture medium and stimulated by the presence of inducer in the culture medium. Endo-pectinase was basically inducible and was only produced when pectin was used as carbon source. Our results suggest that pectinases in A. flavipes FP-500 are produced in a concerted way. The first enzyme to be produced was exopectinase followed by Pectin Lyase and Endo-pectinase.

Avaliou-se o crescimento e a produção de enzimas por Aspergillus flavipes FP-500 em pectina, ácido poligalacturônico, ácido galacturônico, arabinose, ramnose, xilose, glicerol e glicose, em diferentes valores de pH inicial. Verificamos que a cepa produziu exopectinases, endopectinases e pectina liases. Exopectinases e pectina liases foram produzidas em níveis basais como enzimas constitutivas e sua produção foi modulada pela fonte de carbono disponível e pelo pH do meio de cultura e estimulada pela presença de indutores no meio de cultura. Endopectinase foi indutível e produzida somente quando pectina foi utilizada como fonte de carbono. Nossos resultados sugerem que as pectinases de A. flavipes FP-500 são produzidas de forma planejada. A primeira enzima a ser produzida foi expopectinase, seguida por pectina liase e endopectinase.

Novel process for the simultaneous extraction and degumming of banana fibers under solid-state cultivation

Various process parameters for the production of polygalacturonase by Streptomyces lydicus under solid-state fermentation were optimized. The optimum particle size of wheat bran for polygalacturonase production was in the range of 500-1000 µm. Initial moisture content of 70 percent was found to be the optimum for enzyme production. The most suitable inoculum size was 1.25 x 10(5) CFU/mL and the optimum incubation temperature was 30ºC. Addition of carbon sources resulted in 37 percent increase in enzyme yield (425 U/g), whereas no significant enhancement was obtained on nitrogen supplementation. Maximum enzyme yield was recorded at 72 h. When compared to the initial production medium (108.5 U/g), the enzyme yield was 3.9 fold after optimization. Solid-state fermentation was effectively employed to develop a novel process for the simultaneous extraction and degumming of banana fibers. Streptomyces lydicus was allowed to grow on wheat bran medium in which banana leaf sheath pieces were incorporated and the fiber bundles were separated after a two-step fermentative process.

Vários parâmetros de processo de produção de poligalacturonase por Streptomyces lydicus por fermentação em estado sólido foram otimizados. O tamanho ótimo de partícula de farelo de trigo para a produção de poligalacturonase esteve na faixa de 500 a 1000 mm. O teor inicial de umidade de 70 por cento foi o melhor para a produção da enzima. O inóculo inicial mais adequado foi de 1,25 x 10(5) UFC/mL e a temperatura ótima de incubação foi 30ºC. A adição de fontes de carbono resultou em aumento de 37 por cento no rendimento da enzima (425U/g), enquanto que a suplementação com nitrogênio não melhorou o rendimento. O rendimento máximo da enzima foi obtido em 72h. A otimização resultou em um aumento de 3,9 vezes na quantidade de enzima produzida inicialmente (108,5U/g). A fermentação em estado-sólido foi eficiente para o desenvolvimento de um novo processo de extração e simultânea degomagem. Streptomyces lydicus foi cultivado em meio de farelo de trigo acrescentado de fragmentos de folhas de banana, sendo os feixes de fibras separados após um processo de fermentação em dois passos.

Estudio de la actividad enzimatica de poligalacturonasaen la corteza de pitaya amarilla (Acanthocereus pitajaya) / Polygalacturonase Activity in Yellow Pitaya Peel (Acanthocereus pitajaya)

Se determinó la actividad poligalacturonasa en corteza de pitaya amarilla (Acanthocereus pitajaya). El buffer fosfato de sodio 20 mM pH 7,0 con NaCl 0,5 M se constituyó en el sistema más efectivo para la extracción. Se obtuvieron valores óptimos de actividad a pH 5,0 en buffer citratos, a una temperatura de 40 °C. Los valores de KM y VMÁX hallados para esta enzima fueron 2,9 mg ácido poligalacturónico/ml y 0,076 nmol de azúcares reductores/s, respectivamente. Los resultados muestran que la poligalacturonasa está vinculada con el ablandamiento de este fruto.

Purification and characterization of a novel pectinase from Acrophialophora nainiana with emphasis on its physicochemical properties.

An extracellular pectinase (PECI) was purified to apparent homogeneity from liquid state cultures of the thermophilic fungus Acrophialophora nainiana by ultrafiltration and a combination of gel filtration and ion-exchange chromatographic procedures. The molecular masses of PECI were 35,500 and 30,749 Da, as determined by SDS-PAGE and mass spectrometry, respectively. It was more active at 60 degrees C and pH 8.0 and showed high stability at 50 degrees C with half-life of 7 days. However at 60 and 70 degrees C, PECI was much less stable with half lives of approximately 20 and 3 min, respectively. The thermostability of purified PECI was also investigated by fluorescence and circular dichroism spectroscopy. Fluorescence revealed that the unfolding transition region was observed between 45 and 70 degrees C. A major decrease in the stability was found at 70 degrees C. Circular dichroism measurements at pH between 5.0 and 9.0 showed a transition temperature (T(m)) range of 50-55 degrees . The thermodynamic analysis of these results showed that EPGI is thermal stable protein exhibiting maximum stability (DeltaG(25)) of 22.65 and 19.19 kcal/mol at pH 8.0 and 9.0, respectively. The apparent K(m) value on pectin from citrus fruits was 4.22 mgml(-1). PECI exhibited no detectable activity of pectin methylesterase, endo-polygalacturonase, mannanase, xylanase and cellulase. However, it showed exo-polygalacturonase and pectin lyase activities. The presence of carbohydrate was detected in the pure PECI. It was activated by l-tryptophan, DEPC, DTT, DTNB, DTP, l-cystein and beta-mercaptoethanol and inhibited by NBS, Fe(2+), Cu(2+), Zn(2+), Mn(2+), Al(3+) and Ca(2+). The enzyme showed homology with a pectin lyases from Xanthomonas campestris and Bacillus licheniformis.

Biochemical and nutritional characterization of three prickly pear species with different ripening behavior.

Biochemical and nutritional changes were studied during the ripening process of three Opuntia morphospecies with different ripening behavior: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Esmeralda (Opuntia sp.) of early, early-intermediate, and intermediate-late ripening, respectively. In loss of fresh weight, Naranjona showed the highest values, while in Blanca Cristalina and Esmeralda, a discrete weight loss was found. No significant differences were found among morphospecies in soluble solids, total titratable acidity and pH during the postharvest days. Blanca Cristalina and Esmeralda showed an increase in the content of carotenoids, while these diminished in Naranjona. The cell wall enzymes evaluated showed particular behaviors during the ripening of each morphospecies suggesting a fine biochemical control and not a clear relationship between fruit softening and enzyme activity. This study provides basic information on prickly pear ripening, in order to understand this process for its control and for improving shelf life.

Growth and pectinase production by Aspergillus Mexican strain protoplast regenerated under acidic stress.

Protoplasts from Aspergillus sp. FP-180 and Aspergillus awamori NRRL- 3112 were released and regenerated at extreme acidic conditions. The best conditions for protoplast release were 0.8 M KCI, pH 5.8, and 3 h of digestion using mycelia from 12- to 16-h cultures from either Aspergillus sp. FP-180 or A. awamori NRRL-3112. The addition of fresh mycelia to an ongoing digestion after 1 h increased protoplast 4.5-5 times. A regeneration efficiency of 90% was attained at pH 6.0, and it was possible to regenerate protoplasts at pH 1.7 with a regeneration efficiency of 0.5% for Aspergillus sp. FP-180. The LpH-10 strain, derived from protoplast from Aspergillus sp FP-180, was able to regenerate at pH 1.7 and grow at pH values as low as 1.5, values at which the original strain is unable to grow. Regeneration at extreme pH improved the performance of LpH-10 strain. It showed a twofold increase in cell growth at pH 2.0 in liquid culture and a higher pectinolytic activity in relation to that produced by the original strain.

Yeasts associated with fresh and frozen pulps of Brazilian tropical fruits.

The occurrence of yeasts on ripe fruits and frozen pulps of pitanga (Eugenia uniflora L), mangaba (Hancornia speciosa Gom.), umbu (Spondias tuberosa Avr. Cam.), and acerola (Malpighia glaba L) was verified. The incidence of proteolytic, pectinolytic, and mycocinogenic yeasts on these communities was also determined. A total of 480 colonies was isolated and grouped in 405 different strains. These corresponded to 42 ascomycetous and 28 basidiomycetous species. Candida sorbosivorans, Pseudozyma antarctica, C. spandovensis-like, C. spandovensis, Kloeckera apis, C. parapsilosis, Rhodotorula graminis, Kluyveromyces marxianus, Cryptococcus laurentii, Metchnikowia sp (isolated only from pitanga ripe fruits), Issatchenkia occidentalis and C. krusei (isolated only from mangaba frozen pulps), were the most frequent species. The yeast communities from pitanga ripe fruits exhibited the highest frequency of species, followed by communities from acerola ripe fruits and mangaba frozen pulps. Yeast communities from frozen pulp and ripe fruits of umbu had the lowest number of species. Except the yeasts from pitanga, yeast communities from frozen pulp exhibited higher number of yeasts than ripe fruit communities. Mycocinogenic yeasts were found in all of the substrates studied except in communities from umbu ripe fruits and pitanga frozen pulps. Most of the yeasts found to produce mycocins were basidiomycetes and included P. antarctica, Cryptococcus albidus, C. bhutanensis-like, R. graminis and R. mucilaginosa-like from pitanga ripe fruits as well as black yeasts from pitanga and acerola ripe fruits. The umbu frozen pulps community had the highest frequency of proteolytic species. Yeasts able to hydrolyse casein at pH 5.0 represented 38.5% of the species isolated. Thirty-seven percent of yeast isolates were able to hydrolyse casein at pH 7.0. Pectinolytic yeasts were found in all of the communities studied, excepted for those of umbu frozen pulps. The highest frequency of pectinolytic activity was found in mangaba frozen pulp communities. Around 30% of all isolates produced pectinases. The ability to split arbutin was observed in all communities ranging from 8% in yeasts from pitanga frozen pulps to 40.6% in acerola ripe fruit communities. Among 432 species tested, 125 were active for beta-glucosidase production, and Kloeckera apis, P. antarctica, C. sorbosivorans, and C. spandovensis-like were the most active species.

Evoluçäo da atividade e expressäo de enzimas e modificaçäo de polímeros da parede celular de mamöes durante o amadurecimento / Evolution of the activity and enzyme expression and modification of the cellular wall of papayas during the ripening

Foram analisadas expressão dos genes e atividades enzimáticas da pectinametilesterase, beta-galactosidase e poligalacturonase, bem como modificação in situ de polímeros da parede celular de frutos de mamão em diversos estádios de amadurecimento. Após a clonagem e sequenciamento de fragmentos do gene para cada enzima sua expressão foi analisada por Northern blot. A imunolocalização dos polímeros da parede foi feita por microscopia eletrônica. De acordo com os resultados apresentados, é possível evidenciar indução da transcrição do gene para a beta-galactosidase, presença constante de transcrito para a poligalcaturonase e ausência de evidências da expressão do gene para pectinametilesterase...

Screening of bacterial strains for pectinolytic activity: characterization of the polygalacturonase produced by "Bacillus" sp

One hundred sixty eight bacterial strains, isolated from soil and samples of vegetable in decomposition, were screened for the use of citrus pectin as the sole carbon source. 102 were positive for pectinase depolymerization in assay plates as evidenced by clear hydrolization halos. Among them, 30(per cent) presented considerable pectinolytic activity. The cultivation of these strains by submerged and semi-solid fermentation for polygalacturose production indicated that five strains of "Bacillus" sp. produced high quantities of the enzyme. The physico-chemical characteristics, such as optimum pH of 6.0-7.0, optimum temperatures between 45ºC and 55ºC, stability at temperatures above 40ºC and in neutral and alkaline pH, were determined