RESUMO

The establishment of an efficient and feasible biorefinery model depends on, among other factors, particularly the selection of the most appropriate microorganism. Mucor circinelloides is a dimorphic fungus species able to produce a wide variety of hydrolytic enzymes, lipids prone to biodiesel production, carotenoids, ethanol, and biomass with significant nutritional value. M. circinelloides also has been selected as a model species for genetic modification by being the first filamentous oleaginous species to have its genome fully characterized, as well as being a species characterized as a potential bioremediation agent. Considering the potential of replacing several nonrenewable feedstocks is widely dependent on fossil fuels, the exploitation of microbial processes and products is a desirable solution for promoting a green and sustainable future. Here, we introduce and thoroughly describe the recent and critical applications of this remarkable fungus within the context of developing a fungal-based biorefinery.

Assuntos

RESUMO

The zygomycete fungus Lichtheimia ramosa H71D, isolated from sugarcane bagasse compost, was identified by applying phylogenetic analysis based on the DNA sequence of the Internal Transcribed Spacer (ITS), and subsequent secondary structure analysis of ITS2. L. ramosa H71D was able to grow over a wide range of temperatures (25-45 °C), manifesting optimal growth at 37 °C. A 64 kDa xylanase (named LrXynA) was purified from the culture supernatant of L. ramosa H71D grown on 2% carboxymethylcellulose (CMC), as the only carbon source. LrXynA displayed optimal activity at pH 6 and temperature of 65 °C. The enzyme retained more than 50% of its maximal activity over a broad range of pH values (4.5-7.5). Enzyme half-life (t½) times at 55, 65 and 75 °C were 80, 25, and 8 min, respectively. LrXynA showed higher affinity (k M of 2.87 mg/mL) and catalytic efficiency (k cat /k M of 0.651 mg s/mL) towards Beechwood xylan in comparison to other substrates such as Birchwood xylan, Oat-spelt xylan, CMC, Avicel and Solka floc. The predominant final products from LrXynA-mediated hydrolysis of Beechwood xylan were xylobiose and xylotriose, suggesting that the enzyme is an endo-ß-1,4 xylanase. Scanning electron microscopy (SEM) imaging of sugar cane bagasse (SCB) treated with LrXynA, alone or in combination with commercial cellulases, showed a positive effect on the hydrolysis of SCB. To our knowledge, this is the first report focusing on the biochemical and functional characterization of an endo-ß-1,4 xylanase from the thermotolerant and fast-growing fungus Lichtheimia ramosa.

RESUMO

Para sobreviverem na temperatura corpórea de seu hospedeiro, os fungos patogênicos têm desenvolvido mecanismos moleculares importantes, como a expressão de proteínas relacionadas ao crescimento em altas temperaturas. Assim, o objetivo deste trabalho foi analisar o crescimento in vitro de Conidiobolus lamprauges em diferentes temperaturas e comparar o perfil de proteínas expressas através de eletroforese bidimensional (2D), em duas temperaturas distintas, sendo uma considerada baixa (28°C) e alta (37°C). Para análise do crescimento em diferentes temperaturas, cinco isolados de C. lamprauges, oriundos de ovinos doentes, foram incubados a 20, 25, 30, 35 e 40°C e o crescimento radial foi medido a cada 24 horas. Para análise da expressão diferencial, realizou-se a extração de proteínas do fungo cultivado a 28°C e a 37°C por 48 horas. A média de crescimento radial dos isolados foi diferente nas temperaturas analisadas, sendo 35°C a melhor temperatura para crescimento em todas as amostras. A temperatura ótima ajustada variou entre 33,3°C a 34,8°C. Os limites inferior e superior de inibição de crescimento foram 18°C e 42°C, respectivamente. Na análise da expressão diferencial, foram encontrados 16 spots diferencialmente expressos, sete (7/16) estavam com expressão diminuída e nove (9/16) com expressão aumentada a 37°C, quando comparado a 28°C. Além disso, oito spots estavam presentes apenas a 28°C e seis a 37°C. Sugere-se que C. lamprauges produza um perfil de proteínas relacionadas à termorregulação desencadeado pela alta temperatura do hospedeiro.(AU)

To survive at the body temperature of their hosts, pathogenic fungi have developed important molecular mechanisms, such as protein expression associated with growth at high temperatures. Thus, the aim of this study was to analyze the in vitro growth of Conidiobolus lamprauges at different temperatures and compare proteins expressed by two-dimensional electrophoresis (2D), for the pathogen cultivated at low (28°C) and high (37°C) temperatures. For the analysis of growth temperatures, five isolates of C. lamprauges from sick sheep were incubated at 20, 25, 30, 35 and 40°C and radial growth was measured every 24 hours. For the analysis of differential expression, protein extraction and two-dimensional polyacrylamide gel electrophoresis were performed with C. lamprauges cultivated at 28°C and 37°C for 48 hours. The average radial growth was different at the temperatures tested, and 35°C was found to be the best growth temperature for all isolates. The optimum adjusted temperature ranged between 33.3°C and 34.8°C. The upper and lower limits of growth inhibition were 18°C and 42°C, respectively. Upon expression analysis, a total of 16 spots were differentially expressed, seven (7/16) proteins were downregulated and nine (9/16) were over-expressed at 37ºC compared to 28°C. In addition, eight spots were present only at 28ºC and six were present only at 37ºC. It is suggested that C. lamprauges produces a profile of proteins that is related to thermoregulation triggered by the high temperature of the host.(AU)

Assuntos

RESUMO

Para sobreviverem na temperatura corpórea de seu hospedeiro, os fungos patogênicos têm desenvolvido mecanismos moleculares importantes, como a expressão de proteínas relacionadas ao crescimento em altas temperaturas. Assim, o objetivo deste trabalho foi analisar o crescimento in vitro de Conidiobolus lamprauges em diferentes temperaturas e comparar o perfil de proteínas expressas através de eletroforese bidimensional (2D), em duas temperaturas distintas, sendo uma considerada baixa (28°C) e alta (37°C). Para análise do crescimento em diferentes temperaturas, cinco isolados de C. lamprauges, oriundos de ovinos doentes, foram incubados a 20, 25, 30, 35 e 40°C e o crescimento radial foi medido a cada 24 horas. Para análise da expressão diferencial, realizou-se a extração de proteínas do fungo cultivado a 28°C e a 37°C por 48 horas. A média de crescimento radial dos isolados foi diferente nas temperaturas analisadas, sendo 35°C a melhor temperatura para crescimento em todas as amostras. A temperatura ótima ajustada variou entre 33,3°C a 34,8°C. Os limites inferior e superior de inibição de crescimento foram 18°C e 42°C, respectivamente. Na análise da expressão diferencial, foram encontrados 16 spots diferencialmente expressos, sete (7/16) estavam com expressão diminuída e nove (9/16) com expressão aumentada a 37°C, quando comparado a 28°C. Além disso, oito spots estavam presentes apenas a 28°C e seis a 37°C. Sugere-se que C. lamprauges produza um perfil de proteínas relacionadas à termorregulação desencadeado pela alta temperatura do hospedeiro.

To survive at the body temperature of their hosts, pathogenic fungi have developed important molecular mechanisms, such as protein expression associated with growth at high temperatures. Thus, the aim of this study was to analyze the in vitro growth of Conidiobolus lamprauges at different temperatures and compare proteins expressed by two-dimensional electrophoresis (2D), for the pathogen cultivated at low (28°C) and high (37°C) temperatures. For the analysis of growth temperatures, five isolates of C. lamprauges from sick sheep were incubated at 20, 25, 30, 35 and 40°C and radial growth was measured every 24 hours. For the analysis of differential expression, protein extraction and two-dimensional polyacrylamide gel electrophoresis were performed with C. lamprauges cultivated at 28°C and 37°C for 48 hours. The average radial growth was different at the temperatures tested, and 35°C was found to be the best growth temperature for all isolates. The optimum adjusted temperature ranged between 33.3°C and 34.8°C. The upper and lower limits of growth inhibition were 18°C and 42°C, respectively. Upon expression analysis, a total of 16 spots were differentially expressed, seven (7/16) proteins were downregulated and nine (9/16) were over-expressed at 37ºC compared to 28°C. In addition, eight spots were present only at 28ºC and six were present only at 37ºC. It is suggested that C. lamprauges produces a profile of proteins that is related to thermoregulation triggered by the high temperature of the host.

RESUMO

Zygomycosis is an infection caused by opportunistic fungi of the Zygomycetes class, specifically those from the Mucorales and Entomophthorales orders. It is an uncommon disease, mainly restricted to immunocompromised patients. We report a case of a 73-year-old male patient with a history of fever (39°C) lasting for 1 day, accompanied by shivering, trembling, and intense asthenia. The patient was admitted to the intensive care unit with complex partial seizures, and submitted to orotracheal intubation and mechanical ventilation under sedation with midazolam. The electroencephalogram showed evidence of non-convulsive status epilepticus. There is no fast specific laboratory test that permits confirmation of invasive fungal disease. Unless the physician suspects this condition, the disease may progress rapidly while the patient is treated with broad-spectrum antibiotics. Differential diagnosis between fungal and bacterial infection is often difficult. The clinical presentation is sometimes atypical, and etiological investigation is not always successful. In the present case, the histopathological examination of the biopsy obtained from the right temporal lobe indicated the presence of irregular, round, thick-walled fungi forming papillae and elongated structures of irregular diameter, with no septa, indicative of zygomycete (Basidiobolus). Treatment with liposomal amphotericin B and fluconazole was initiated after diagnosis of meningoencephalitis by zygomycete, with a successful outcome.

Assuntos