Abstract: The oleaginous yeasts Lipomyces starkey were grown
in the presence of dairy industry wastewaters (DIW). The yeasts were
able to degrade the organic components of DIW and to produce a
significant fraction of their biomass as triglycerides.
When using DIW from the Ricotta cheese production or residual
whey as growth medium, the L. starkey could be cultured without
dilution nor external organic supplement. On the contrary, the yeasts
could only partially degrade the DIW from the Mozzarella cheese
production, due to the accumulation of a metabolic product beyond
the threshold of toxicity. In this case, a dilution of the DIW was
required to obtain a more efficient degradation of the carbon
compounds and an higher yield in oleaginous biomass.
The fatty acid distribution of the microbial oils obtained showed a
prevalence of oleic acid, and is compatible with the production of a II
generation biodiesel offering a good resistance to oxidation as well as
an excellent cold-performance.
Abstract: Microbial oil was produced by soil isolated
oleaginous yeast YU5/2 in flask-batch fermentation. The yeast was
identified by molecular genetics technique based on sequence
analysis of the variable D1/D2 domain of the large subunit (26S)
ribosomal DNA and it was identified as Torulaspora globosa. T.
globosa YU5/2 supported maximum values of 0.520 g/L/d, 0.472 g
lipid/g cells, 4.16 g/L, and 0.156 g/L/d for volumetric lipid
production rate, and specific yield of lipid, lipid concentration, and
specific rate of lipid production respectively, when culture was
performed in nitrogen-limiting medium supplemented with 80g/L
glucose. Among the carbon sources tested, maximum cell yield
coefficient (YX/S, g/L), maximum specific yield of lipid (YP/X, g
lipid/g cells) and volumetric lipid production rate (QP, g/L/d) were
found of 0.728, 0.237, and 0.619, respectively, using sweet potato
tubers hydrolysates as carbon source.
Abstract: Monoculture and mixed cultures of microalgae and
the oleaginous yeast for microbial oil productions were investigated
using sugarcane juice as carbon substrate. The monoculture of yeast
Torulaspora maleeae Y30, Torulaspora globosa YU5/2 grew faster
than that of microalgae Chlorella sp. KKU-S2. In monoculture of T.
maleeae Y30, a biomass of 8.267g/L with lipid yield of 0.920g/L
were obtained, while 8.333g/L of biomass with lipid yield of
1.141g/L were obtained for monoculture of T. globosa YU5/2. A
biomass of 1.933g/L with lipid yield of 0.052g/L was found for
monoculture of Chlorella sp. KKU-S2. The biomass concentration in
the mixed culture of the oleaginous yeast with microalgae increased
faster and was higher compared with that in the monocultures. A
biomass of 8.733g/L with lipid yield of 1.564g/L was obtained for a
mixed culture of T. maleeae Y30 with Chlorella sp. KKU-S2, while
8.010g/L of biomass with lipid yield of 2.424g/L was found for
mixed culture of T. globosa YU5/2 with Chlorella sp. KKU-S2.
Maximum cell yield coefficient (YX/S, g/L) was found of 0.323 in
monoculture of Chlorella sp. KKU-S2 but low level of both specific
yield of lipid (YP/X, g lipid/g cells) of 0.027 and volumetric lipid
production rate (QP, g/L/d) of 0.003 were observed. While, maximum
YP/X (0.303), QP (0.105) and maximum process product yield (YP/S,
0.061) were obtained in mixed culture of T. globosa YU5/2 with
Chlorella sp. KKU-S2. The results obtained from the study shows
that mixed culture of yeast with microalgae is a desirable cultivation
process for microbial oil production.
Abstract: Compared to oil production from microorganisms, little work has been performed for mixed culture of microalgae and yeast. In this article it is aimed to show high oil accumulation potential of mixed culture of microalgae Chlorella sp. KKU-S2 and oleaginous yeast Torulaspora maleeae Y30 using sugarcane molasses as substrate. The monoculture of T. maleeae Y30 grew faster than that of microalgae Chlorella sp. KKU-S2. In monoculture of yeast, a biomass of 6.4g/L with specific growth rate (m) of 0.265 (1/d) and lipid yield of 0.466g/L were obtained, while 2.53g/L of biomass with m of 0.133 (1/d) and lipid yield of 0.132g/L were obtained for monoculture of Chlorella sp. KKU-S2. The biomass concentration in the mixed culture of T. maleeae Y30 with Chlorella sp. KKU-S2 increased faster and was higher compared with that in the monoculture and mixed culture of microalgae. In mixed culture of microalgae Chlorella sp. KKU-S2 and C. vulgaris TISTR8580, a biomass of 3.47g/L and lipid yield of 0.123 g/L were obtained. In mixed culture of T. maleeae Y30 with Chlorella sp. KKU-S2, a maximum biomass of 7.33 g/L and lipid yield of 0.808g/L were obtained. Maximum cell yield coefficient (YX/S, 0.229g/L), specific yield of lipid (YP/X, 0.11g lipid/g cells) and volumetric lipid production rate (QP, 0.115 g/L/d) were obtained in mixed culture of yeast and microalgae. Clearly, T. maleeae Y30 and Chlorella sp. KKU-S2 use sugarcane molasses as organic nutrients efficiently in mixed culture under mixotrophic growth. The biomass productivity and lipid yield are notably enhanced in comparison with monoculture.