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Sitepu I.R.,University of California at Davis | Sitepu I.R.,Forestry Research and Development Agency FORDA | Garay L.A.,University of California at Davis | Sestric R.,University of Manitoba | And 4 more authors.
Biotechnology Advances | Year: 2014

Production of biodiesel from edible plant oils is quickly expanding worldwide to fill a need for renewable, environmentally-friendly liquid transportation fuels. Due to concerns over use of edible commodities for fuels, production of biodiesel from non-edible oils including microbial oils is being developed. Microalgae biodiesel is approaching commercial viability, but has some inherent limitations such as requirements for sunlight. While yeast oils have been studied for decades, recent years have seen significant developments including discovery of new oleaginous yeast species and strains, greater understanding of the metabolic pathways that determine oleaginicity, optimization of cultivation processes for conversion of various types of waste plant biomass to oil using oleaginous yeasts, and development of strains with enhanced oil production. This review examines aspects of oleaginous yeasts not covered in depth in other recent reviews. Topics include the history of oleaginous yeast research, especially advances in the early 20th century; the phylogenetic diversity of oleaginous species, beyond the few species commonly studied; and physiological characteristics that should be considered when choosing yeast species and strains to be utilized for conversion of a given type of plant biomass to oleochemicals. Standardized terms are proposed for units that describe yeast cell mass and lipid production. © 2014. Source

Kallio M.H.,Center for International Forestry Research | Kanninen M.,Center for International Forestry Research | Rohadi D.,Forestry Research and Development Agency FORDA
Forests Trees and Livelihoods | Year: 2011

The differences in socio-economic and perceptional characteristics between tree planting and nontree planting farmers were analysed in four case studies from three provinces in Indonesia. For each case study, the paper describes: a) the reasons for planting or not planting trees, b) how the income received from wood was used, c) the main disadvantages related to tree planting, and d) farmers willingness to continue tree planting under the current arrangements. The tree planters were mainly the farmers with more land; higher value of total assets; and with more active participation in farmer's groups or other social organizations. Long rotation length, lack of capital, low wood prices, and poor access to production inputs or markets affected farmers' willingness to plant trees in the future. Policies are needed that are conducive to the establishment of markets for fiber and timber with fair and reasonable pricing structures. © 2011 A B Academic Publishers-Printed in Great Britain. Source

Sitepu I.,University of California at Davis | Sitepu I.,Forestry Research and Development Agency FORDA | Selby T.,University of California at Davis | Lin T.,University of California at Davis | And 2 more authors.
Journal of Industrial Microbiology and Biotechnology | Year: 2014

Conversion of lignocellulosic hydrolysates to lipids using oleaginous (high lipid) yeasts requires alignment of the hydrolysate composition with the characteristics of the yeast strain, including ability to utilize certain nutrients, ability to grow independently of costly nutrients such as vitamins, and ability to tolerate inhibitors. Some combination of these characteristics may be present in wild strains. In this study, 48 oleaginous yeast strains belonging to 45 species were tested for ability to utilize carbon sources associated with lignocellulosic hydrolysates, tolerate inhibitors, and grow in medium without supplemented vitamins. Some well-studied oleaginous yeast species, as well as some that have not been frequently utilized in research or industrial production, emerged as promising candidates for industrial use due to ability to utilize many carbon sources, including Cryptococcus aureus, Cryptococcus laurentii, Hannaella aff. zeae, Tremella encephala, and Trichosporon coremiiforme. Other species excelled in inhibitor tolerance, including Candida aff. tropicalis, Cyberlindnera jadinii, Metschnikowia pulcherrima, Schwanniomyces occidentalis and Wickerhamomyces ciferrii. No yeast tested could utilize all carbon sources and tolerate all inhibitors tested. These results indicate that yeast strains should be selected based on characteristics compatible with the composition of the targeted hydrolysate. Other factors to consider include the production of valuable co-products such as carotenoids, availability of genetic tools, biosafety level, and flocculation of the yeast strain. The data generated in this study will aid in aligning yeasts with compatible hydrolysates for conversion of carbohydrates to lipids to be used for biofuels and other oleochemicals. © 2014 Society for Industrial Microbiology and Biotechnology. Source

Sitepu I.R.,University of California at Davis | Sitepu I.R.,Forestry Research and Development Agency FORDA | Jin M.,Michigan State University | Fernandez J.E.,University of California at Davis | And 3 more authors.
Applied Microbiology and Biotechnology | Year: 2014

Microbial oil is a potential alternative to food/plant-derived biodiesel fuel. Our previous screening studies identified a wide range of oleaginous yeast species, using a defined laboratory medium known to stimulate lipid accumulation. In this study, the ability of these yeasts to grow and accumulate lipids was further investigated in synthetic hydrolysate (SynH) and authentic ammonia fiber expansion (AFEX™)-pretreated corn stover hydrolysate (ACSH). Most yeast strains tested were able to accumulate lipids in SynH, but only a few were able to grow and accumulate lipids in ACSH medium. Cryptococcus humicola UCDFST 10-1004 was able to accumulate as high as 15.5 g/L lipids, out of a total of 36 g/L cellular biomass when grown in ACSH, with a cellular lipid content of 40 % of cell dry weight. This lipid production is among the highest reported values for oleaginous yeasts grown in authentic hydrolysate. Preculturing in SynH media with xylose as sole carbon source enabled yeasts to assimilate both glucose and xylose more efficiently in the subsequent hydrolysate medium. This study demonstrates that ACSH is a suitable medium for certain oleaginous yeasts to convert lignocellullosic sugars to triacylglycerols for production of biodiesel and other valuable oleochemicals. © 2014 Springer-Verlag. Source

Race D.,Australian National University | Sumirat B.,Forestry Research and Development Agency FORDA
International Journal of Sustainable Development | Year: 2015

Community forestry has been developed internationally as a policy response to reduce deforestation and to improve the livelihoods of forest-dependent communities. This article discusses the social dimension of community forestry, and uses the concept of social capital to analyse the implications of social inequalities in two community forestry initiatives in Indonesia. The article concludes with some revealing insights about the: 1) temporal nature of social capital in community forestry; 2) ways social capital can entrench inequalities; 3) role of 'outsiders' assisting the development of community forestry. Copyright © 2015 Inderscience Enterprises Ltd. Source

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