Single Cell Oil Production from Undetoxified Arundo donax L. hydrolysate by Cutaneotrichosporon curvatus.

The use of low-cost substrates represents one key issue to make single cell oil production sustainable. Among low-input crops, Arundo donax L. is a perennial herbaceous rhizomatous grass containing both C5 and C6 carbohydrates. The scope of the present work was to investigate and optimize the production of lipids by the oleaginous yeast Cutaneotrichosporon curvatus from undetoxified lignocellulosic hydrolysates of steam-pretreated A. donax. The growth of C. curvatus was first optimized in synthetic media, similar in terms of sugar concentration to hydrolysates, by applying the response surface methodology (RSM) analysis. Then the bioconversion of undetoxified hydrolysates was investigated. A fed-batch process for the fermentation of A. donax hydrolysates was finally implemented in a 2-L bioreactor. Under optimized conditions, the total lipid content was 64% of the dry cell weight and the lipid yield was 63% of the theoretical. The fatty acid profile of C. curvatus triglycerides contained 27% palmitic acid, 33% oleic acid and 32% linoleic acid. These results proved the potential of lipid production from A. donax, which is particularly important for their consideration as substitutes for vegetable oils in many applications such as biodiesel or bioplastics.

Hydrolysis of Corn Stover by Talaromyces cellulolyticus Enzymes: Evaluation of the Residual Enzymes Activities Through the Process.

The obtainment of sugars from lignocellulosic residues represents a sustainable and versatile platform for the production of a number of bio-based products. Cellulases are a family of enzymes which can effectively hydrolyze the biomass polysaccharides at mild conditions. Cellulolytic fungi belonging to the genera Trichoderma and Aspergillus are the most commonly source of commercial cellulases used so far. More recently, Talaromyces cellulolyticus was also scored as a promising cellulases producer. In comparison to the Trichoderma and Aspergillus systems, Talaromyces enzymes have been less investigated. The present research dealt with the conversion of steam-pretreated corn stover by commercial blend of T. cellulolyticus enzymes with respect to the common blends. The paper also investigated the stability of the enzyme preparation and tested the use of additives (namely Tween 80, Tween 20, and BSA) to improve the enzymes performances and the hydrolysis efficiency. The results indicated that, at the same process conditions, T. cellulolyticus cellulases were more effective and yielded 20% more sugars compared to control blends. Furthermore, the cellulase components displayed a synergistic interaction with hemicellulases. The results indicate that cellulases from T. cellulolyticus are less affected by the high dry matter consistency and the use of additives could increase the total activity by around 50% and ß-glucosidase capacity by 10-15%.

Effect of cerium on growth and antioxidant metabolism of Lemna minor L.

An increasing input rate of rare earth elements in the environment is expected because of the intense extraction of such elements form their ores to face human technological needs. In this study Lemna minor L. plants were grown under laboratory conditions and treated with increasing concentrations of cerium (Ce) ions to investigate the effects on plant growth and antioxidant systems. The growth increased in plants treated with lower Ce concentrations and reduced in plants treated with higher concentrations, compared to control plants. In plants treated with higher Ce concentrations lower levels of chlorophyll and carotenoid and the appearance of chlorotic symptoms were also detected. Increased levels of hydrogen peroxide, antioxidant metabolites and antioxidant activity confirmed that higher Ce concentrations are toxic to L. minor. Ce concentration in plant tissues was also determined and detectable levels were found only in plants grown on Ce-supplemented media. The use of duckweed plants as a tool for biomonitoring of Ce in freshwater is discussed.

Yeast lipids from cardoon stalks, stranded driftwood and olive tree pruning residues as possible extra sources of oils for producing biofuels and biochemicals.

BACKGROUND: Some lignocellulosic biomass feedstocks occur in Mediterranean Countries. They are still largely unexploited and cause considerable problems due to the lack of cost-effective harvesting, storage and disposal technologies. Recent studies found that some basidiomycetous yeasts are able to accumulate high amount of intracellular lipids for biorefinery processes (i.e., biofuels and biochemicals). Accordingly, the above biomass feedstocks could be used as carbon sources (after their pre-treatment and hydrolysis) for lipid accumulation by oleaginous yeasts. RESULTS: Cardoon stalks, stranded driftwood and olive tree pruning residues were pre-treated with steam-explosion and enzymatic hydrolysis for releasing free mono- and oligosaccharides. Lipid accumulation tests were performed at two temperatures (20 and 25 °C) using Leucosporidium creatinivorum DBVPG 4794, Naganishia adeliensis DBVPG 5195 and Solicoccozyma terricola DBVPG 5870. S. terricola grown on cardoon stalks at 20 °C exhibited the highest lipid production (13.20 g/l), a lipid yield (28.95%) close to the maximum theoretical value and a lipid composition similar to that found in palm oil. On the contrary, N. adeliensis grown on stranded driftwood and olive tree pruning residues exhibited a lipid composition similar to those of olive and almonds oils. A predictive evaluation of the physical properties of the potential biodiesel obtainable by lipids produced by tested yeast strains has been reported and discussed. CONCLUSIONS: Lipids produced by some basidiomycetous yeasts grown on Mediterranean lignocellulosic biomass feedstocks could be used as supplementary sources of oils for producing biofuels and biochemicals.