Advances in metabolic engineering of non-conventional yeasts / 生物工程学报

Over the past 30 years, Yarrowia lipolytica, Kluyveromyces, Pichia, Candida, Hansenula and other non-conventional yeasts have attracted wide attention because of their desirable phenotypes, such as rapid growth, capability of utilizing multiple substrates, and stress tolerance. A variety of synthetic biology tools are being developed for exploitation of their unique phenotypes, making them potential cell factories for the production of recombinant proteins and renewable bio-based chemicals. This review summarizes the gene editing tools and the metabolic engineering strategies recently developed for non-conventional yeasts. Moreover, the challenges and future perspectives for developing non-conventional yeasts into efficient cell factories for the production of useful products through metabolic engineering are discussed.

Enhanced pyruvic acid yield in an osmotic stress-resistant mutant of Yarrowia lipolytica

BACKGROUND: Pyruvic acid (PA), a vital α-oxocarboxylic acid, plays an important role in energy and carbon metabolism. The oleaginous yeast Yarrowia lipolytica (Y. lipolytica) has considerable potential for the production of PA. An increased NaCl concentration reportedly increases the biomass and PA yield of Y. lipolytica. RESULTS: To increase the yield of PA, the NaCl-tolerant Y. lipolytica A4 mutant was produced using the atmospheric and room temperature plasma method of mutation. The A4 mutant showed growth on medium containing 160 g/L NaCl. The PA yield of the A4 mutant reached 97.2 g/L at 120 h (0.795 g/g glycerol) in a 20-L fermenter with glycerol as the sole carbon source, which was 28.9% higher than that of the parental strain. CONCLUSION: The PA yield from Y. lipolytica can be improved by increasing its NaCl tolerance.

Judicialização da saúde na garantia do acesso ao medicamento / The judicialisation of health as a means ensuring access to medicines / La Judicialización de la salud como garantía de acceso a medicamentos

Objetivo Visando conhecer o impacto das demandas judiciais sobre a organização dos serviços públicos de saúde, realizou-se uma revisáo sistemática com enfoque na "judicialização da saúde" para fornecimento de medicamentos. Métodos Foram analisados artigos originais publicados no período de 2007 a 2011, na literatura nacional e internacional, resultando no total de 49239 artigos disponíveis nas bases de dados Science Direct e BIREME. Resultados A pesquisa indicou predominância da bibliografia proveniente do Brasil, principalmente do sudeste, bem como de estudo realizado na Colômbia. Discursáo Dentre os pleitos, configuraram-se como principais agravos relatados as doenças crônicas, podendo-se citar: diabetes, hipertensáo, cânceres e artrite reumatóide. Por serem afecções parte de programas específicos do Sistema Único de Saúde, a dificuldade de acesso a esses fármacos e consequente judicialização da saúde demonstrou a fragilidade das políticas públicas existentes. Conclusão Por fim, conclui-se que a via judicial, apesar de ser uma estratégia para garantir o acesso ao medicamento, apresenta inabilidade para lidar com o julgamento das ações e gera, dessa forma, distorções no fluxo dos sistemas públicos.

Objective A systematic review, focusing on the judicialisation of health regarding gaining access to medicines, was aimed at understanding the impact of lawsuits on the organisation of public health services. Method Original articles published between 2007 and 2011 in the pertinent national and international literature were analysed, resulting in 49,239 articles being found in Science Direct and BIREME databases. Results The survey indicated a predominance of literature from Brazil, mainly the southeast, as well as a study from Colombia. Discussion The aforementioned chronic disease-related claims involved diabetes, high blood pressure, cancer and rheumatoid arthritis. Forming part of specific Unified Healthcare System programmes highlighted the difficulty in gaining access to the appropriate medicine and consequent health judicialisation demonstrated the fragility of existing public policy. Conclusion It was concluded that the courts (despite being a strategy for ensuring access to medicine) were unable to deal with the current spate of lawsuits, thereby leading to disruption regarding the flow of public systems.

Objetivo El estudio tiene como objetivo evaluar el impacto de las demandas judiciales sobre la organización de los servicios públicos de salud, mediante la realización de una revisión sistemática centrada en el uso de los tribunales para el suministro de medicamentos. Método Fueron identificados 49239 artículos en las bases de datos Science Direct e BIREME. Resultado El estudio indicó que la mayor parte de la bibliografía es de Brasil, con uno estudio en Colombia. Discusión Aparecen como los principales trastornos de salud relatados a las enfermedades crónicas, se pueden citar: la diabetes, la hipertensión, el cáncer y la artritis reumatoide. Debido a que son parte de los programas específicos de lo sistema de salud, la dificultad de acceso a estos fármacos y la consiguiente judicialización de la salud de manifiesto la fragilidad de las políticas públicas existentes. Conclusiones Por último, está la conclusión de que los tribunales, a pesar de ser una estrategia para garantizar el acceso a la medicina, presenta incapacidad para hacer frente al juicio de las acciones y por lo tanto genera distorsiones en el flujo de los sistemas públicos.

Optimization of biomass production of a mutant of Yarrowia lipolytica with an increased lipase activity using raw glycerol

The yeast Yarrowia lipolytica accumulates oils and is able to produce extracellular lipases when growing in different carbon sources including glycerol, the principal by-product of the biodiesel industry. In this study, biomass production of a novel mutant strain of Y. lipolytica was statistically optimized by Response Surface Methodology in media containing biodiesel-derived glycerol as main carbon source. This strain exhibited distinctive morphological and fatty acid profile characteristics, and showed an increased extracellular lipase activity. An organic source of nitrogen and the addition of 1.0 g/l olive oil were necessary for significant lipase production. Plackett-Burman and Central Composite Statistical Designs were employed for screening and optimization of fermentation in shaken flasks cultures, and the maximum values obtained were 16.1 g/l for biomass and 12.2 Units/ml for lipase, respectively. Optimized batch bioprocess was thereafter scaled in aerated bioreactors and the values reached for lipase specific activity after 95 % of the glycerol had been consumed, were three-fold higher than those obtained in shaken flasks cultures. A sustainable bioprocess to obtain biomass and extracellular lipase activity was attained by maximizing the use of the by-products of biodiesel industry.

Optimización de la producción de biomasa usando glicerol crudo, de una cepa mutante de Yarrowia lipolytica con actividad incrementada de lipasa. La levadura Yarrowia lipolytica acumula aceites y produce una lipasa extracelular al crecer en diferentes fuentes de carbono, entre ellas el glicerol, principal subproducto de la creciente industria del biodiésel. En el presente trabajo, se optimizó mediante la metodología de superficies de respuesta la producción de biomasa de una nueva cepa mutante de Y. lipolytica, empleando medios con glicerol derivado de la industria del biodiésel como principal fuente de carbono. Esta cepa presentó características morfológicas y perfil de ácidos grasos distintivos, y una mayor actividad de lipasa extracelular. Para obtener una producción significativa de lipasa extracelular, fue necesario el agregado de una fuente orgánica de nitrógeno y de 1 g/l de aceite de oliva. Se utilizaron los diseños estadísticos de Plackett-Burman y central compuesto para la selección y la optimización de las fermentaciones en frascos agitados; los máximos valores de biomasa y de lipasa obtenidos fueron de 16,1 g/l y 12,2 unidades/ml, respectivamente. Luego, el bioproceso en lote optimizado se escaló a biorreactores aireados, y los valores de actividad específica de lipasa alcanzados después de haberse consumido el 95 % del glicerol fueron tres veces más altos que los obtenidos en los cultivos en frascos agitados. En suma, se desarrolló un bioproceso sostenible para la obtención de biomasa y de una actividad de lipasa extracelular, que a la vez maximiza el uso de subproductos de la industria del biodiésel.

Evaluation of pathogenic fungi occurrence in traumatogenic structures of freshwater fish / Avaliação da ocorrência de fungos patogênicos em estruturas traumatogênicas de peixes fluviais

INTRODUCTION: Fungal infections in human skin, such as sporotrichosis, can occur after fish induced trauma. This work aimed to identify fungi in freshwater fish that are pathogenic to humans. METHODS: Extraction of dental arches from Serrassalmus maculatus (piranha) and Hoplias malabaricus (wolf fish), stings from Pimelodus maculatus (mandis catfish), dorsal fin rays from Plagioscion spp. (corvina) and Tilapia spp., for culture in Mycosel agar. Some cultures were submitted to DNA extraction for molecular identification by sequencing ITS-5.8S rDNA. RESULTS: Cultures identified most yeast as Candida spp., while sequencing also permitted the identification of Phoma spp. and Yarrowia lipolytica. CONCLUSIONS: While the search for S. schenckii was negative, the presence of fungus of the genera Phoma and Candida revealed the pathogenic potential of this infection route. The genus Phoma is involved in certain forms of phaeohyphomycosis, a subcutaneous mycosis caused by dematiaceous fungi, with reports of infections in human organs and systems. Traumatizing structures of some freshwater fish present pathogenic fungi and this may be an important infection route that must be considered in some regions of Brazil, since there are a large number of a fisherman in constant contact with traumatogenic fish.

INTRODUÇÃO: Infecções fúngicas na pele humana (como a esporotricose) podem se manifestar após traumatismos por peixes. O objetivo deste trabalho é procurar fungos patogênicos para o homem em peixes fluviais. MÉTODOS: Extração de arcadas dentárias Serrassalmus maculatus (piranha) e Hoplias malabaricus (traíra), ferrões de Pimelodus maculatus (mandis), raios da nadadeira dorsal de Plagioscion spp. (corvina) e Tilapia spp. para a realização do cultivo em agar Mycosel. Algumas culturas foram submetidas à extração de DNA para a identificação molecular pelo seqüenciamento da região ITS-5.8S do rDNA. RESULTADOS: As culturas mostraram que a maioria das leveduras era Candida spp. e o sequenciamento também permitiu a identificação de Phoma spp. e Yarrowia lipolytica. CONCLUSÕES: Embora a pesquisa para S. schenckii tenha sido negativa, a presença de fungos do gênero Phoma e Candida revela o potencial patogênico desta via de infecção. O gênero Phoma está envolvido em alguns casos de feohifomicoses, micoses subcutâneas causadas por fungos dematiáceos com relatos de infecções em órgãos e sistemas humanos. As estruturas traumatizantes de alguns peixes fluviais apresentam fungos patogênicos e esta pode ser uma importante via de infecção que deve ser considerada em algumas regiões do Brasil, uma vez que há um grande número de pescadores e peixes traumatogênicos.

Properties of alkaline protease genetically engineered on cell surface of the yeast Yarrowia lipolytica.

ALP2 gene encoding alkaline protease cloned from Aureobasidium pullulans HN2-3 was ligated into the surface display plasmid and expressed in the cells of the yeast Yarrowia lipolytica. The expressed alkaline protease was immobilized on the yeast cells. The activity of the immobilized enzyme with 6 His tag was found to be significantly higher than that of without 6 His tag. The immobilized enzyme showed lower optimal temperature and a lower affinity for azocasein than the free enzyme purified from A. pullulans HN2-3. The thermal stability of the immobilized enzyme enhanced and the pH stability decreased, compared to that of the free enzyme.