ABSTRACT
In this study, semi-pilot scale microbial oil production by Trichosporon cutaneum using medium containing corncob acid hydrolysate was carried out in a 50-L fermentor. Scale up showed no negative influence on lipid fermentation that no obvious lag phase was observed. Both glucose and xylose could be utilized simultaneously by T. cutaneum, but the utilization rate of xylose was much slower than that of glucose. After 7.6 days of fermentation, the biomass, lipid content, and lipid yield were 21.8 g/L, 53.7 %, and 11.7 g/L, respectively. Also, a high lipid coefficient (lipid yield on sugars consumption) of 26.3 was obtained. Besides microbial oil, polysaccharide was another main product of lipid fermentation that the remaining biomass residue full of polysaccharides after lipid extraction could be one important by-product in future. Overall, this study showed the great potential of industrialization for lipid production by T. cutaneum on low-cost substrates especially for lignocellulosic hydrolysates.
Subject(s)
Fermentation , Lipids/isolation & purification , Oils/chemistry , Trichosporon/chemistry , Acids/chemistry , Biomass , Fungal Polysaccharides/biosynthesis , Fungal Polysaccharides/chemistry , Fungal Polysaccharides/isolation & purification , Hydrolysis , Lipids/biosynthesis , Lipids/chemistry , Oils/isolation & purification , Oils/metabolism , Protein Hydrolysates/chemistry , Trichosporon/metabolism , Zea mays/chemistryABSTRACT
In present study, the beneficial effect of corncob acid hydrolysate environment on lipid fermentation of Trichosporon dermatis was elucidated by method of cell biology (mainly using flow cytometry and microscope) for the first time. Propidium iodide (PI) and rhodamine 123 (Rh123) staining showed that corncob acid hydrolysate environment was favorable for the cell membrane integrity and mitochondrial membrane potential of T. dermatis and thus made its lipid fermentation more efficient. Nile red (NR) staining showed that corncob acid hydrolysate environment made the lipid accumulation of T. dermatis slower, but this influence was not serious. Moreover, the cell morphology of T. dermatis elongated in the corncob acid hydrolysate, but the cell morphology changed as elliptical-like during fermentation. Overall, this work offers one simple and effective method to evaluate the influence of lignocellulosic hydrolysates environment on lipid fermentation.
Subject(s)
Dermatitis/metabolism , Fermentation , Lipids/biosynthesis , Protein Hydrolysates/chemistry , Acids/chemistry , Basidiomycota/chemistry , Cell Membrane/drug effects , Cellular Microenvironment/genetics , Dermatitis/microbiology , Flow Cytometry , Hydrolysis , Lignin/chemistry , Lignin/metabolism , Lipids/chemistry , Trichosporon/chemistry , Trichosporon/enzymology , Zea mays/chemistry , Zea mays/metabolismABSTRACT
In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven.
