Abstract: Mixotrophic cultivation of the isolated freshwater microalgae Chlorella sp. KKU-S2 in batch shake flask for biomass and lipid productions, different concentration of glucose as carbon substrate, different nitrogen source and concentrations were investigated. Using 1.0g/L of NaNO3 as nitrogen source, the maximum biomass yield of 10.04g/L with biomass productivity of 1.673g/L d was obtained using 40g/L glucose, while a biomass of 7.09, 8.55 and 9.45g/L with biomass productivity of 1.182, 1.425 and 1.575g/L d were found at 20, 30 and 50g/L glucose, respectively. The maximum lipid yield of 3.99g/L with lipid productivity of 0.665g/L d was obtained when 40g/L glucose was used. Lipid yield of 1.50, 3.34 and 3.66g/L with lipid productivity of 0.250, 0.557 and 0.610g/L d were found when using the initial concentration of glucose at 20, 30 and 50g/L, respectively. Process product yield (YP/S) of 0.078, 0.119, 0.158 and 0.094 were observed when glucose concentration was 20, 30, 40 and 50 g/L, respectively. The results obtained from the study shows that mixotrophic culture of Chlorella sp. KKU-S2 is a desirable cultivation process for microbial lipid and biomass production.
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.
Abstract: The objective of this work is to produce heterotrophic
microalgal lipid in flask-batch fermentation. Chlorella sp. KKU-S2
supported maximum values of 0.374 g/L/d, 0.478 g lipid/g cells, and
0.112 g/L/d for volumetric lipid production rate, and specific yield of
lipid, and specific rate of lipid production, respectively when culture
was performed on BG-11 medium supplemented with 50g/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 sugarcane molasses as carbon
source. The main components of fatty acid from extracted lipid were
palmitic acid, stearic acid, oleic acid and linoleic acid which similar
to vegetable oils and suitable for biodiesel production.
Abstract: The objective of this research is to study of microbial lipid production by locally photosynthetic microalgae and oleaginous yeast via integrated cultivation technique using CO2 emissions from yeast fermentation. A maximum specific growth rate of Chlorella sp. KKU-S2 of 0.284 (1/d) was obtained under an integrated cultivation and a maximum lipid yield of 1.339g/L was found after cultivation for 5 days, while 0.969g/L of lipid yield was obtained after day 6 of cultivation time by using CO2 from air. A high value of volumetric lipid production rate (QP, 0.223 g/L/d), specific product yield (YP/X, 0.194), volumetric cell mass production rate (QX, 1.153 g/L/d) were found by using ambient air CO2 coupled with CO2 emissions from yeast fermentation. Overall lipid yield of 8.33 g/L was obtained (1.339 g/L of Chlorella sp. KKU-S2 and 7.06g/L of T. maleeae Y30) while low lipid yield of 0.969g/L was found using non-integrated cultivation technique. To our knowledge this is the unique report about the lipid production from locally microalgae Chlorella sp. KKU-S2 and yeast T. maleeae Y30 in an integrated technique to improve the biomass and lipid yield by using CO2 emissions from yeast fermentation.