Addressing the Concern of Orange-Yellow Fungus Growth on Palm Kernel Cake: Safeguarding Dairy Cattle Diets for Mycotoxin-Producing Fungi.

Palm kernel cake (PKC), a byproduct of palm oil extraction, serves an important role in Ecuador's animal feed industry. The emergence of yellow-orange fungal growth in PKC on some cattle farms in Ecuador sparked concerns within the cattle industry regarding a potential mycotoxin-producing fungus on this substrate. Due to the limited availability of analytical chemistry techniques in Ecuador for mycotoxin detection, we chose to isolate and identify the fungus to determine its association with mycotoxin-producing genera. Through molecular identification via ITS region sequencing, we identified the yellow-orange fungus as the yeast Candida ethanolica. Furthermore, we isolated two other fungi-the yeast Pichia kudriavzevii, and the fungus Geotrichum candidum. Molecular identification confirmed that all three species are not classified as mycotoxin-producing fungi but in contrast, the literature indicates that all three have demonstrated antifungal activity against Aspergillus and Penicillium species, genera associated with mycotoxin production. This suggests their potential use in biocontrol to counter the colonization of harmful fungi. We discuss preventive measures against the fungal invasion of PKC and emphasize the importance of promptly identifying fungi on this substrate. Rapid recognition of mycotoxin-producing and pathogenic genera holds the promise of mitigating cattle intoxication and the dissemination of mycotoxins throughout the food chain.

Rare Yeasts in Latin America: Uncommon Yet Meaningful.

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

Invasive Fungal Infection Caused by Magnusiomyces capitatus in an Immunocompromised Pediatric Patient with Acute Lymphoblastic Leukemia in Mexico City: A Case Report.

Magnusiomyces capitatus (also denominated "Geotrichum capitatum" and "the teleomorph stage of Saprochaete capitata") mainly affects immunocompromised patients with hematological malignancies in rare cases of invasive fungal infections (IFIs). Few cases have been reported for pediatric patients with acute lymphoblastic leukemia (ALL), in part because conventional diagnostic methods do not consistently detect M. capitatus in infections. The current contribution describes a systemic infection in a 15-year-old female diagnosed with ALL. She arrived at the Children's Hospital of Mexico City with a fever and neutropenia and developed symptoms of septic shock 4 days later. M. capitatus ENCB-HI-834, the causal agent, was isolated from the patient's blood, urine, bile, and peritoneal fluid samples. It was identified with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and a phylogenetic reconstruction using internal transcribed spacer (ITS) and 28S ribosomal sequences. The phylogenetic sequence of M. capitatus ENCB-HI-834 clustered with other M. capitatus-type strains with a 100% identity. In vitro antifungal testing, conducted with the Sensititre YeastOne susceptibility system, found the following minimum inhibitory concentration (MIC) values (µg/mL): posaconazole 0.25, amphotericin B 1.0, fluconazole > 8.0, itraconazole 0.25, ketoconazole 0.5, 5-flucytosine ≤ 0.06, voriconazole 0.25, and caspofungin > 16.0. No clinical breakpoints have been defined for M. capitatus. This is the first clinical case reported in Mexico of an IFI caused by M. capitatus in a pediatric patient with ALL. It emphasizes the importance of close monitoring for a timely and accurate diagnosis of neutropenia-related IFIs to determine the proper treatment with antibiotics, antifungals, and chemotherapy for instance including children with ALL.

Postharvest sour rot control in lemon fruit by natamycin and an Allium extract.

Citrus sour rot caused by Geotrichum citri-aurantii is one of the most important postharvest diseases in citrus fruit, causing huge economic losses. Traditionally, it has been controlled by the postharvest application of guazatine and propiconazole fungicides, but restrictions in their use make it urgent to find an alternative for sour rot management. Natamycin, a common food preservative, and the organosulfuric compounds extracted from Allium species are safe food additives that control different foodborne pathogens. In the present study, the curative activities of commercial formulations of natamycin (Fruitgard Nat 20) and an Allium extract (PTSO: propyl thiosulfinate oxide; Proallium FRD®), were evaluated for the control of G. citri-aurantii in artificially inoculated lemon fruit. Trials in laboratory and in commercial conditions were carried out to explore the feasibility of including both compounds as part of a safe postharvest sour rot disease control strategy. Under controlled laboratory conditions, sour rot was significatively reduced by 500 mg L-1 of natamycin, 580 mL L-1 of PTSO and 290 mL L-1 of PTSO + 4% of a food coat, applied by immersion. Nevertheless, the maximum dose of PTSO (580 mL L-1) caused phytotoxicity on the fruit rind. In commercial drenching conditions, 290 mL L-1 of PTSO + 4% of a food coat reduced sour rot incidence similar to conventional treatment. In a packing line treatment, spray application of 500 mg L-1 of natamycin with a previous dip in sodium bicarbonate, resulted in nearly 70% reduction of disease incidence compared to conventional salt application. A second commercial experiment revealed that fruit drenching with 290 mL L-1 of PTSO + 4% food coat followed by an in-line cascade application of 500 mg L-1 of natamycin is completely effective for sour rot control after 20 days at 5 °C. Further exposure at room temperature for 7 d showed a 61% reduction in sour rot incidence compared to the control. Results revealed that natamycin and PTSO are promising tools for sour rot control used alone or combined as part of an integrated postharvest strategy.

Geotrichum spp: An overlooked and fatal etiologic agent in immunocompromised patients. A case series from a referral center in Mexico.

Geotrichum spp. is an emergent pathogen. We aimed to describe Geotrichum spp. invasive fungal infections (IFI) in patients from Mexico. We reviewed cases with Geotrichum spp. isolated in clinical samples, from 2001 to 2019. Descriptive analysis was used for clinical data. Twenty patients with proven/probable Geotrichum spp. IFI were analyzed. The median age was 43; 55% were males. Hematologic malignancy was found in 60% (12/20); 75% (15/20) received systemic immunosuppressors. The most common presentation was lower respiratory tract infection. In-hospital mortality was 45% (9/20). Geotrichum spp. should be acknowledged as a pathogen causing atypical pneumonia in immunocompromised Latin American patients. LAY SUMMARY: Geotrichum spp. causes invasive infection in immunocompromised hosts. We describe a case series of 20 patients from Mexico City. Hematologic malignancy was the most common comorbidity. Clinical presentation was mainly lower respiratory tract infection. Mortality was high despite antifungal therapy.

Purification of a killer toxin from Aureobasidium pullulans for the biocontrol of phytopathogens.

The objectives of the present study were to purify and assess the killer toxin effect produced by Aureobasidium pullulans under casual agents of green mold (Penicillum digitatum) and sour rot (Geotrichum citri-aurantii). Initially, different methods of protein precipitation were tested. The proteolytic activity and the presence of proteins acting on cell wall receptors, ß-1,3-glucanase and chitinase were determined, and toxin purification was conducted by Sephadex G-75 gel exclusion chromatography and cellulose chromatography (medium fibers). Subsequently, purification was confirmed by polyacrylamide gel electrophoresis, and the detection of killer activity was performed in solid YEPD-methylene blue buffered with citrate-phosphate (0.1 M, pH 4.6). Toxin identification was performed by liquid chromatography-mass spectrometry. The results showed that the best protein precipitation method was 2:1 ethanol (vol/vol ethanol/supernatant). It was possible to observe the presence of enzymes with proteolytic activity, including ß-1,3-glucanase and chitinase. During the purification process, it was verified that the killer toxin produced by the yeast has a low-molecular-weight protein belonging to the ubiquitin family, which presents killer activity against P. digitatum and G. citri-aurantii.

Biocatalytic production of Ɛ-caprolactone using Geotrichum candidum cells immobilized on functionalized silica.

Immobilization of the Geotrichum candidum (CCT 1205) cell with functionalized silica creates promising biocatalysts for production of ɛ-caprolactone. The results obtained by immobilization of the whole cell on SiO2-NH2 and SiO2-SH supports indicate that the presence of reactive functional groups on the support may promote effective chemical bonds with the cell walls resulting the decreased dehydrogenases enzyme activity (5% yield in less than 2h) and consequently, increased Baeyer-Villiger monooxygenases enzyme activity with redacting of 25% of time reaction when is used SiO2-NH2 as support and 50% through use of SiO2-SH as support relative to free cells when cyclohexanone is used as a substrate. The catalysts SiO2-NH2-Geotrichum candidum and SiO2-SH-Geotrichum candidum were recycling and reused in the ɛ-caprolactone synthesis from cyclohexanone, and the biocatalysts promoted a quantitative conversion up to the eighth reaction cycle. KEY POINTS: • Immobilized microorganism is more efficient than free cell in the caprolactone synthesis. • The reaction times for amino and thiol groups in support were 3 h and 2 h, respectively. • These catalysts showed higher ɛ-caprolactone conversion at higher concentrations.

Production of volatile compounds by yeasts using hydrolysed grape seed oil obtained by immobilized lipases in continuous packed-bed reactors.

Lipases CAL-B, TLL, and RML were used in the synthesis of free fatty acids of grape seed oil as heterogeneous substrate. The best enzyme was used to optimize the reaction variables temperature, enzyme content, and molar ratio of water:oil in batch reactions using experimental planning. The ideal conditions to produce free fatty acids using pure RML were 45 °C, 12:1 substrate molar ratio, and 15% enzyme, resulting in 66% of oil hydrolysis and a productivity of 0.54 mol L-1 min-1 in 4 h of reaction at 180 rpm. Repeated batches of reaction were performed testing the operational stability of RML, results showing that this enzyme could be used for at least 20 cycles keeping more than 80% of its initial activity, suggesting its potential use in industrial processes. The synthesis of free fatty acids was then evaluated in continuous reactions using packed-bed reactor (PBR). The highest productivity in the continuous process was 6.85 mol L-1 min-1, using only RML, showing an operational stability higher than 80% of its initial conversion capacity after 11 days of operation, at a flow rate of 0.13 mL min-1 at 45 °C. We evaluated the use of this hydrolyzed oil as substrate for lactone bioproduction using Galactomyces geotrichum UFMG-CM-Y3276, G. geotrichum UFMG-CM-Y3558, and Geotrichum klebahnii UFMG-CM-Y3014 screened for their oil-hydrolysis ability. Volatile compounds were qualitatively identified in GC-MS as γ-octalactone and γ-nonalactone.

Biofilm production by Aureobasidium pullulans improves biocontrol against sour rot in citrus.

The biocontrol efficiency of Aureobasidium pullulans strain ACBL-77 against Geotrichum citri-aurantii, causal agent of sour rot in citrus, and their interactions were evaluated. For this, were evaluated the incorporation of nutrients in optimizing the antagonistic activity of the yeast, the competition for nutrients between microorganisms, the effect of nutrients on yeast cell and biofilm production and their correlation in the biocontrol of disease, the survival of yeast in citrus fruits and the interaction between microorganisms using scanning electron microscopy. Micronutrients (boric acid, cobalt chloride and ammonium molybdate) favoured the antagonistic action of A. pullulans. Ammonium sulfate 1% and sucrose 0.5% favoured the yeast during the competition between the microorganisms. The addition of ammonium sulfate (1%) in the yeast culture stimulated biofilm production and increased the antagonistic activity against the disease, as also allowed the better survival of yeast in wounded sites of citrus fruit. The yeast was found to be able to form biofilms on citrus, deforming the pathogen hyphae. These results showed the importance of the addition of nutrients in A. pullulans based-formulations when aiming for their use on a commercial scale. This is the first report of a positive correlation between the increase in the quantity of biofilm produced by A. pullulans, with increased antagonistic activity.

Thermoduric psychrotrophic proteolytic microbiota from refrigerated raw milk / Microbiota termodúrica psicrotrófica proteolítica do leite cru refrigerado

Thermoduric microorganisms may withstand high temperatures during the pasteurization of milk. Therefore, the microbiota in pasteurized milk consist of thermoduric microbes and directly influence the shelf-life of the milk. The aim of this study was to identify thermoduric psychrotrophic proteolytic microbiota in refrigerated raw milk. Twenty samples, previously heat-treated, were streaked and incubated at 7°C for 10 days. The strains isolated were streaked on milk agar to assess proteolytic activity and were initially analyzed morphologically by light microscopy and then by molecular techniques to identify the species. In 40% of the samples analyzed was observed only one bacterial growth and others 10 thermoduric psychrotrophic fungi. All isolates were proteolytic. The sequencing of 16S rRNA gene identified the bacterial strain as Bacillus pumilus and analysis of the ITS1-5.8S-ITS2 region of fungal isolates revealed the Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), and the 3 remaining strains were identified as Geotrichum candidum (30%). This is a fist description of B. pumilus in Brazilian raw milk. Considering the spoilage potential of all isolates and of the fungi present in raw milk and their survival in pasteurized milk, it is extremely important to carry out further studies to your resistant to heat, their impact on the shelf-life of pasteurized milk, ultra-high temperature (UHT) milk and dairy products.(AU)

Os micro-organismos termodúricos são aqueles capazes de resistir ao processo de pasteurização do leite. Assim, a microbiota do leite pasteurizado é constituída por esses micro-organismos que podem influenciar diretamente na vida sua vida útil. O objetivo do presente trabalho foi identificar a microbiota termodurica psicrotrófica proteolítica do leite cru refrigerado. Foram avaliadas 20 amostras de leite cru refrigerado, plaqueadas e incubadas a 7°C por 10 dias. As cepas isolados foram repicadas em ágar leite para verificação da atividade proteolítica e inicialmente avaliadas microscopicamente e posteriormente identificadas por sequenciamento de DNA. Foi observado apenas um crescimento bacteriano e outros 10 isolados fúngicos termodúricos psicrotróficos em 40% das amostras avaliadas. Todos os isolados foram proteolíticos. O sequenciamento parcial do gene 16S rRNA da cepa bacteriana permitiu a identificação de Bacillus pumilus e a análise da região ITS1-5.8S-ITS2 dos isolados fúngicos os identificou como Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), e Geotrichum candidum (30%). Não foram encontrados estudos anteriores sobre a presença de B. pumilus no leite cru brasileiro. Considerando o potencial deteriorante de todos os isolados e presença de fungos termodúricos psicrotróficos no leite cru, é importante a continuidade trabalhos que avaliem sua resistência térmica e seu impacto na vida útil do leite pasteurizado, longa vida e derivados.(AU)

Thermoduric psychrotrophic proteolytic microbiota from refrigerated raw milk / Microbiota termodúrica psicrotrófica proteolítica do leite cru refrigerado

Thermoduric microorganisms may withstand high temperatures during the pasteurization of milk. Therefore, the microbiota in pasteurized milk consist of thermoduric microbes and directly influence the shelf-life of the milk. The aim of this study was to identify thermoduric psychrotrophic proteolytic microbiota in refrigerated raw milk. Twenty samples, previously heat-treated, were streaked and incubated at 7°C for 10 days. The strains isolated were streaked on milk agar to assess proteolytic activity and were initially analyzed morphologically by light microscopy and then by molecular techniques to identify the species. In 40% of the samples analyzed was observed only one bacterial growth and others 10 thermoduric psychrotrophic fungi. All isolates were proteolytic. The sequencing of 16S rRNA gene identified the bacterial strain as Bacillus pumilus and analysis of the ITS1-5.8S-ITS2 region of fungal isolates revealed the Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), and the 3 remaining strains were identified as Geotrichum candidum (30%). This is a fist description of B. pumilus in Brazilian raw milk. Considering the spoilage potential of all isolates and of the fungi present in raw milk and their survival in pasteurized milk, it is extremely important to carry out further studies to your resistant to heat, their impact on the shelf-life of pasteurized milk, ultra-high temperature (UHT) milk and dairy products.

Os micro-organismos termodúricos são aqueles capazes de resistir ao processo de pasteurização do leite. Assim, a microbiota do leite pasteurizado é constituída por esses micro-organismos que podem influenciar diretamente na vida sua vida útil. O objetivo do presente trabalho foi identificar a microbiota termodurica psicrotrófica proteolítica do leite cru refrigerado. Foram avaliadas 20 amostras de leite cru refrigerado, plaqueadas e incubadas a 7°C por 10 dias. As cepas isolados foram repicadas em ágar leite para verificação da atividade proteolítica e inicialmente avaliadas microscopicamente e posteriormente identificadas por sequenciamento de DNA. Foi observado apenas um crescimento bacteriano e outros 10 isolados fúngicos termodúricos psicrotróficos em 40% das amostras avaliadas. Todos os isolados foram proteolíticos. O sequenciamento parcial do gene 16S rRNA da cepa bacteriana permitiu a identificação de Bacillus pumilus e a análise da região ITS1-5.8S-ITS2 dos isolados fúngicos os identificou como Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), e Geotrichum candidum (30%). Não foram encontrados estudos anteriores sobre a presença de B. pumilus no leite cru brasileiro. Considerando o potencial deteriorante de todos os isolados e presença de fungos termodúricos psicrotróficos no leite cru, é importante a continuidade trabalhos que avaliem sua resistência térmica e seu impacto na vida útil do leite pasteurizado, longa vida e derivados.

Thermoduric psychrotrophic proteolytic microbiota from refrigerated raw milk / Microbiota termodúrica psicrotrófica proteolítica do leite cru refrigerado

Thermoduric microorganisms may withstand high temperatures during the pasteurization of milk. Therefore, the microbiota in pasteurized milk consist of thermoduric microbes and directly influence the shelf-life of the milk. The aim of this study was to identify thermoduric psychrotrophic proteolytic microbiota in refrigerated raw milk. Twenty samples, previously heat-treated, were streaked and incubated at 7C for 10 days. The strains isolated were streaked on milk agar to assess proteolytic activity and were initially analyzed morphologically by light microscopy and then by molecular techniques to identify the species. In 40% of the samples analyzed was observed only one bacterial growth and others 10 thermoduric psychrotrophic fungi. All isolates were proteolytic. The sequencing of 16S rRNA gene identified the bacterial strain as Bacillus pumilus and analysis of the ITS1-5.8S-ITS2 region of fungal isolates revealed the Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), and the 3 remaining strains were identified as Geotrichum candidum (30%). This is a fist description of B. pumilus in Brazilian raw milk. Considering the spoilage potential of all isolates and of the fungi present in raw milk and their survival in pasteurized milk, it is extremely important to carry out further studies to your resistant to heat, their impact on the shelf-life of pasteurized milk,

Os micro-organismos termodúricos são aqueles capazes de resistir ao processo de pasteurização do leite. Assim, a microbiota do leite pasteurizado é constituída por esses micro-organismos que podem influenciar diretamente na vida sua vida útil. O objetivo do presente trabalho foi identificar a microbiota termodurica psicrotrófica proteolítica do leite cru refrigerado. Foram avaliadas 20 amostras de leite cru refrigerado, plaqueadas e incubadas a 7C por 10 dias. As cepas isolados foram repicadas em ágar leite para verificação da atividade proteolítica e inicialmente avaliadas microscopicamente e posteriormente identificadas por sequenciamento de DNA. Foi observado apenas um crescimento bacteriano e outros 10 isolados fúngicos termodúricos psicrotróficos em 40% das amostras avaliadas. Todos os isolados foram proteolíticos. O sequenciamento parcial do gene 16S rRNA da cepa bacteriana permitiu a identificação de Bacillus pumilus e a análise da região ITS1-5.8S-ITS2 dos isolados fúngicos os identificou como Cladosporium cladosporioides (60%), Curvularia geniculatus (10%), e Geotrichum candidum (30%). Não foram encontrados estudos anteriores sobre a presença de B. pumilus no leite cru brasileiro. Considerando o potencial deteriorante de todos os isolados e presença de fungos termodúricos psicrotróficos no leite cru, é importante a continuidade trabalhos que avaliem sua resistência té

Rare severe mycotic infections in children receiving empirical caspofungin treatment for febrile neutropenia

ABSTRACTEmpirical antifungal therapy is most often given to patients with leukemia. However breakthrough fungal infections under antifungal therapy are not uncommon. Four children, with hematologic malignant disease developed mycotic breakthrough infections while on empirical caspofungin treatment for a median of 14 (range 11-19) days. Trichosporon asahii was detected in the blood culture of two patients and Geotrichum capitatum in the other two (one patient also had positive cerebrospinal fluid culture). Because the patients' clinical situation worsened, voriconazole was empirically added for two patients three and five days before the agent was detected. The first sterile blood culture was obtained 3-7 days of voriconazole treatment. All patients reached clear cultures but one patient died. One patient with central nervous system infection with G. capitatum had severe neurological sequelae. Very severe fungal infections can occur during empirical caspofungin therapy. Therefore, patients should be followed closely.

Invasive infection due to Saprochaete capitata in a young patient with hematological malignancies.

We report a case of invasive infection due to Saprochaete capitata in a patient with hematological malignancies after chemotherapy treatment and empiric antifungal therapy with caspofungin. Although severely immunocompromised the patient survived been treated with amphotericin B lipid complex associated with voriconazole.

Rare severe mycotic infections in children receiving empirical caspofungin treatment for febrile neutropenia.

Empirical antifungal therapy is most often given to patients with leukemia. However breakthrough fungal infections under antifungal therapy are not uncommon. Four children, with hematologic malignant disease developed mycotic breakthrough infections while on empirical caspofungin treatment for a median of 14 (range 11-19) days. Trichosporon asahii was detected in the blood culture of two patients and Geotrichum capitatum in the other two (one patient also had positive cerebrospinal fluid culture). Because the patients' clinical situation worsened, voriconazole was empirically added for two patients three and five days before the agent was detected. The first sterile blood culture was obtained 3-7 days of voriconazole treatment. All patients reached clear cultures but one patient died. One patient with central nervous system infection with G. capitatum had severe neurological sequelae. Very severe fungal infections can occur during empirical caspofungin therapy. Therefore, patients should be followed closely.

Invasive infection due to Saprochaete capitata in a young patient with hematological malignancies

We report a case of invasive infection due to Saprochaete capitata in a patient with hematological malignancies after chemotherapy treatment and empiric antifungal therapy with caspofungin. Although severely immunocompromised the patient survived been treated with amphotericin B lipid complex associated with voriconazole.(AU)

Invasive infection due to Saprochaete capitata in a young patient with hematological malignancies

We report a case of invasive infection due to Saprochaete capitata in a patient with hematological malignancies after chemotherapy treatment and empiric antifungal therapy with caspofungin. Although severely immunocompromised the patient survived been treated with amphotericin B lipid complex associated with voriconazole.

Geotrichum candidum as a possible cause of bovine abortion.

Geotrichum spp. are ubiquitous, saprotrophic fungi found in soil, organic matter, and silage, as a contaminant in food products and in the digestive tracts of mammals. The current study reports a case of Geotrichum candidum infection with dermatitis in an aborted bovine fetus with skin and lung lesions. A 6-month-old aborted male Holstein Friesian fetus displayed unusual lesions on the skin of the abdomen, thorax, and head, which was excessively thickened and wrinkled. These changes corresponded to orthokeratotic hyperkeratosis, neutrophil accumulation in the stratum corneum, a pyogranulomatous inflammatory infiltrate, and superficial dermal necrosis. Moderate suppurative multifocal pneumonia was observed. Large numbers of mononuclear cells and occasional fibrin thrombi within blood vessels were found in the lungs, brain, and cerebellum. Gridley staining revealed fungal structures within the skin lesions. The mycological exam demonstrated the growth of G. candidum, and phase contrast microscopy conducted on the abomasal fluid revealed hyphae compatible with this agent. The skin lesions observed, in association with the fungus isolated, indicated that the abortion was due to G. candidum infection of the bovine fetus.

Imobilização de lipase em matriz polimérica para produção de bioaroma / Immobilization of lipase on polymer matrix for synthesis of flavor

Os ésteres são importantes compostos orgânicos, obtidos por síntese química ou extraídos de alguns produtos naturais utilizando-se solvente em meio adequado. ... O principal objetivo deste trabalho foi a obtenção de acetato de butila, um éster de aroma característico de abacaxi, utilizando lipase de Geotrichum candidum produzida em fermentação submersa e imobilizada em matriz polimérica de alginato de bário e gelatina reticulada com glutaraldeído. A caracterização bioquímica foi realizada tanto para a lipase na forma livre como para a lipase na forma imobilizada. O rendimento em conversão molar de substrato foi determinado por cromatografia gasosa. A enzima apresentou atividade enzimática máxima após 48 horas de fermentação de 37,7 U/mL. Os valores ótimos para pH e temperatura da enzima na forma livre e imobilizada foram pH 6,5 e 40 °C e pH 7,5 e 45 °C, respectivamente. A enzima na forma livre foi estável do pH 6,0 ao 8,0 e à temperatura de 35 a 45 °C, já na forma imobilizada, foi estável do pH 5,5 ao 8,5 e na faixa de temperatura de 30 a 55 °C. A lipase imobilizada teve seus parâmetros cinéticos determinados, e os valores obtidos para o Km e Vmax, foram 0,115 mmol e 0,718 µmol.mL-1.min-1, respectivamente. As melhores condições de síntese do bioaroma para a enzima na forma livre foram: temperatura de 30 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 97,2 % de conversão molar em acetato de butila. Para a enzima imobilizada as melhores condições foram: temperatura de 45 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 99,1%, que demonstra que lipase produzida por Geotrichum candidum na forma imobilizada apresenta excelente capacidade de sintetizar acetato de butila (bioaroma de abacaxi)

Esters are important organic compounds obtained by chemical synthesis or derived from some natural products using a solvent in appropriate medium. Studies have shown that enzymes, particularly lipases, ca be applied in the synthesis of various esters. The main objective of this study was to obtain butyl acetate, a characteristic ester aroma of pineapple, using lipase from Geotrichum candidum produced in submerged fermentation and immobilized in a barium alginate and gelatin polymer matrix crosslinked with glutaraldehyde. The biochemical characterization was performed for both free and immobilized lipases. The yield in molar conversion of substrate was determined by gas chromatography. The enzyme showed maximum enzymatic activity after 48 hours of fermentation of 37.7 U/mL. The optimum values for pH and temperature of the enzyme in free and immobilize form were pH 6.5 and 40 °C and pH 7.5 and 45 °C, respectively. The enzyme was stable in free form from pH 6.0 to 8.0 and at temperatures from 35 to 45 °C, and in the immobilized form from pH 5.5 to 8.5 and at temperatures from 30 to 55 °C. Kinetic parameters of the immobilized lipase were determined, and the values obtained for Km and Vmax were 0.115 mmol and 0.718 µmol.mL-1.min-1, respectively. The best conditions for the synthesis of flavor by enzyme in free form were: 30 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 97.2% of molar conversion in butyl acetate. For the immobilized enzyme the best conditions were: 45 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 99.1%, demonstrating that lipase produced by Geotrichum candidum in immobilized form has an excellent ability to synthesize butyl acetate (pineapple flavor)