Lipid and total fatty acid productivity in photoautotrophic fresh water microalgae: screening studies towards biodiesel production

Microalgae are considered as a promising feedstock for biomass production. The selection of the most suitable species is based on several key parameters such as lipid and fatty acid productivity. In the present study, the growth of different microalgae strains was examined in freshwater media for photoautotrophs suited for large-scale applications to identify the most suitable medium for each species. In the optimal medium, Scenedesmus obliquus showed the highest biomass productivity measured as increase of cell dry weight (0.25 g cellu dry weight (CDW) L^?1 day^?1), while Botryococcus braunii showed the highest lipid and total fatty acid content (430 and 270 mg g^?1 CDW, respectively) among the tested species. Regarding lipid and total fatty acid productivity, S. obliquus was the most lipid and total fatty acid productive strain with 41 and 18 mg L^?1 day^?1 during the exponential phase, respectively. Additionally, the proportion of saturated and monounsaturated fatty acids increased with duration of the incubation in S. obliquus, while polyunsaturated fatty acids decreased. These results nominate S. obliquus as a promising microalga in order to serve as a feedstock for renewable energy production.     

Metabolic engineering of Saccharomyces cerevisiae for the biotechnological production of succinic acid

The production of bio-based succinic acid is receiving great attention, and several predominantly prokaryotic organisms have been evaluated for this purpose. In this study we report on the suitability of the highly acid- and osmotolerant yeast Saccharomyces cerevisiae as a succinic acid production host. We implemented a metabolic engineering strategy for the oxidative production of succinic acid in yeast by deletion of the genes SDH1, SDH2, IDH1 and IDP1. The engineered strains harbor a TCA cycle that is completely interrupted after the intermediates isocitrate and succinate. The strains show no serious growth constraints on glucose. In glucose-grown shake flask cultures, the quadruple deletion strain Δsdh1Δsdh2Δidh1Δidp1 produces succinic acid at a titer of 3.62 g L^?1 (factor 4.8 compared to wild-type) at a yield of 0.11 mol (mol glucose)^?1. Succinic acid is not accumulated intracellularly. This makes the yeast S. cerevisiae a suitable and promising candidate for the biotechnological production of succinic acid on an industrial scale.     

Free fatty acid production in Escherichia coli under phosphate-limited conditions

Microbially synthesized fatty acids are an attractive platform for producing renewable alternatives to petrochemically derived transportation fuels and oleochemicals. Free fatty acids (FFA) are a direct precursor to many high-value compounds that can be made via biochemical and ex vivo catalytic pathways. To be competitive with current petrochemicals, flux through these pathways must be optimized to approach theoretical yields. Using a plasmid-free, FFA-producing strain of Escherichia coli, a set of chemostat experiments were conducted to gather data for FFA production under phosphate limitation. A prior study focused on carbon-limited conditions strongly implicated non-carbon limitations as a preferred media formulation for maximizing FFA yield. Here, additional data were collected to expand an established kinetic model of FFA production and identify targets for further metabolic engineering. The updated model was able to successfully predict the strain’s behavior and FFA production in a batch culture. The highest yield observed under phosphate-limiting conditions (0.1 g FFA/g glucose) was obtained at a dilution rate of 0.1 h^?1, and the highest biomass-specific productivity (0.068 g FFA/gDCW/h) was observed at a dilution rate of 0.25 h^?1. Phosphate limitation increased yield (～45 %) and biomass-specific productivity (～300 %) relative to carbon-limited cultivations using the same strain. FFA production under phosphate limitation also led to a cellular maintenance energy ～400 % higher (0.28 g/gDCW/h) than that seen under carbon limitation.     

Lipid productivity and fatty acid composition-guided selection of Chlorella strains isolated from Malaysia for biodiesel production

The need to develop biomass-based domestic production of high-energy liquid fuels (biodiesel) for transportation can potentially be addressed by exploring microalgae with high lipid content. Selecting the strains with adequate oil yield and quality is of fundamental importance for a cost-efficient biofuel feedstock production based on microalgae. This work evaluated 29 strains of Chlorella isolated from Malaysia as feedstock for biodiesel based on volumetric lipid productivity and fatty acid profiles. Phylogenetic studies based on 18S rRNA gene revealed that majority of the strains belong to true Chlorella followed by Parachlorella. The strains were similarly separated into two groups based on fatty acid composition. Of the 18 true Chlorella strains, Chlorella UMACC187 had the highest palmitic acid (C16:0) content (71.3?±?4.2 % total fatty acids, TFA) followed by UMACC84 (70.1?±?0.7 %TFA), UMACC283 (63.8?±?0.7 %TFA), and UMACC001 (60.3?±?4.0 %TFA). Lipid productivity of the strains at exponential phase ranged from 34.53 to 230.38 mg L^?1 day^?1, with Chlorella UMACC050 attaining the highest lipid productivity. This study demonstrated that Chlorella UMACC050 is a promising candidate for biodiesel feedstock production.     

Analysis of metabolites in the terpenoid pathway of Catharanthus roseus cell suspensions

In Catharanthus roseus cell cultures, the monoterpenoid pathway has been shown to be a limiting factor in terpenoid indole alkaloid (TIA) production. This could be due to competition at the level of isopentenyl diphosphate::dimethylallyl diphosphate (C5) which leads to the biosynthesis of different terpenoid groups. For future engineering of the terpenoid pathway, chemical characterization of C. roseus cell cultures is a necessity. Therefore, in this study nine C. roseus cell suspension lines were characterized by analyzing the levels of the major terpenoids derived from different biosynthetic pathways which may compete for the same precursors; TIA (monoterpenoid, C10), carotenoids (tetraterpenoid, C40), and sterols (triterpenoid, C30). Among the cell lines, CRPP (S) was the most promising TIA-producing cell line which provided more TIA [24 μmol g^?1 dry weight (DW)] than carotenoids (15 μmol g^?1 DW) and sterols (2 μmol g^?1 DW). However, when considering the distribution of the isopentenyl-precursor (C5), the carotenoids which assemble from 8× C5 represent twofold more C5-units (122 μmol g^?1 DW) than the TIA in this cell line. In the CRPP (G), A12A2 (G), and A12A2 (S) cell lines, the C5 distribution was predominant toward carotenoid biosynthesis as well, resulting in a relatively high accumulation of carotenoids. The geranylgeranyl diphosphate (C20) pathway toward carotenoid production is therefore considered competitive toward TIA biosynthesis. For channeling more precursors to the TIA, the branch point for C10 and C20 seems an interesting target for metabolic engineering. Using principal component analysis of the chromatographic data, we characterized the cell lines chemically based on their metabolite levels. The information on the metabolic composition of C. roseus cell cultures is useful for developing strategies to engineer the metabolic pathways and for selection of cell lines for future studies.     

Fumaric Acid Production in Saccharomyces cerevisiae by In Silico Aided Metabolic Engineering

Fumaric acid (FA) is a promising biomass-derived building-block chemical. Bio-based FA production from renewable feedstock is a promising and sustainable alternative to petroleum-based chemical synthesis. Here we report on FA production by direct fermentation using metabolically engineered Saccharomyces cerevisiae with the aid of in silico analysis of a genome-scale metabolic model. First, FUM1 was selected as the target gene on the basis of extensive literature mining. Flux balance analysis (FBA) revealed that FUM1 deletion can lead to FA production and slightly lower growth of S. cerevisiae. The engineered S. cerevisiae strain obtained by deleting FUM1 can produce FA up to a concentration of 610±31 mg L^–1 without any apparent change in growth in fed-batch culture. FT-IR and ¹H and ¹³C NMR spectra confirmed that FA was synthesized by the engineered S. cerevisiae strain. FBA identified pyruvate carboxylase as one of the factors limiting higher FA production. When the RoPYC gene was introduced, S. cerevisiae produced 1134±48 mg L^–1 FA. Furthermore, the final engineered S. cerevisiae strain was able to produce 1675±52 mg L^–1 FA in batch culture when the SFC1 gene encoding a succinate–fumarate transporter was introduced. These results demonstrate that the model shows great predictive capability for metabolic engineering. Moreover, FA production in S. cerevisiae can be efficiently developed with the aid of in silico metabolic engineering.     

An oxidoreduction potential shift control strategy for high purity propionic acid production by Propionibacterium freudenreichii CCTCC M207015 with glycerol as sole carbon source

The effects of oxidoreduction potential (ORP) regulation on the process of propionic acid production by Propionibacterium freudenreichii CCTCC M207015 have been investigated. Potassium ferricyanide and sodium borohydride were determined as ORP control agents through serum bottle experiment. In batch fermentation, cell growth, propionic acid and by-products distribution were changed with ORP levels in the range of 0–160 mV. Based on these analysis results, an ORP-shift control strategy was proposed: at first 156 h, ORP was controlled at 120 mV to obtain higher cell growth rate and propionic acid formation rate, and then it was shifted to 80 mV after 156 h to maintain the higher propionic acid formation rate. By applying this strategy, the optimal parameters were obtained as follows: the propionic acid concentration 45.99 g L^?1, productivity 0.192 g L^?1 h^?1, the proportion of propionic acid to total organic acids 92.26 % (w/w) and glycerol conversion efficiency 76.65 %. The mechanism of ORP regulation was discussed by the ratio of NADH/NAD⁺, ATP levels, and metabolic flux analysis. The results suggest that it is possible to redistribute energy and metabolic fluxes by the ORP-shift control strategy, and the strategy could provide a simple and efficient tool to realize high purity propionic acid production with glycerol as carbon source.     

Expression of exoinulinase genes in Saccharomyces cerevisiae to improve ethanol production from inulin sources

To improve inulin utilization and ethanol fermentation, exoinulinase genes from the yeast Kluyveromyces marxianus and the recently identified yeast, Candida kutaonensis, were expressed in Saccharomyces cerevisiae. S. cerevisiae harboring the exoinulinase gene from C. kutaonensis gave higher ethanol yield and productivity from both inulin (0.38 vs. 0.34 g/g and 1.35 vs. 1.22 g l^?1 h^?1) and Jerusalem artichoke tuber flour (0.47 vs. 0.46 g/g and 1.62 vs. 1.54 g l^?1 h^?1) compared with the strain expressing the exoinulinase gene from K. marxianus. Thus, the exoinulinase gene from C. kutaonensis is advantageous for engineering S. cerevisiae to improve ethanol fermentation from inulin sources.     

Photosynthetic physiological performance and proteomic profiling of the oleaginous algae <Emphasis Type="Italic">Scenedesmus acuminatus</Emphasis> reveal the mechanism of lipid accumulation under low and high nitrogen supplies

In this study, we presented cellular morphological changes, time-resolved biochemical composition, photosynthetic performance and proteomic profiling to capture the photosynthetic physiological response of Scenedesmus acuminatus under low nitrogen (3.6 mM NaNO₃, N^?) and high nitrogen supplies (18.0 mM NaNO₃, N⁺). S. acuminatus cells showed extensive lipid accumulation (53.7% of dry weight) and were enriched in long-chain fatty acids (C16 & C18) under low nitrogen supply. The activity of PSII and photosynthetic rate decreases, whereas non-photochemical quenching and dark respiration rates were increased in the N^? group. In addition, the results indicated a redistribution of light excitation energy between PSII and PSI in S. acuminatus exists before lipid accumulation. The iTRAQ results showed that, under high nitrogen supply, protein abundance of the chlorophyll biosynthesis, the Calvin cycle and ribosomal proteins decreased in S. acuminatus. In contrast, proteins associated with the photosynthetic machinery, except for F-type ATPase, were increased in the N⁺ group (N⁺, 3 vs. 9 days and 3 days, N⁺ vs. N^?). Under low nitrogen supply, proteins involved in central carbon metabolism, fatty acid synthesis and branched-chain amino acid metabolism were increased, whereas the abundance of proteins of the photosynthetic machinery had decreased, with exception of PSI (N^?, 3 vs. 9 days and 9 days, N⁺ vs. N^?). Collectively, the current study has provided a basis for the metabolic engineering of S. acuminatus for biofuel production.     

Xylose isomerase overexpression along with engineering of the pentose phosphate pathway and evolutionary engineering enable rapid xylose utilization and ethanol production by Saccharomyces cerevisiae

Xylose is the main pentose and second most abundant sugar in lignocellulosic feedstocks. To improve xylose utilization, necessary for the cost-effective bioconversion of lignocellulose, several metabolic engineering approaches have been employed in the yeast Saccharomyces cerevisiae. In this study, we describe the rational metabolic engineering of a S. cerevisiae strain, including overexpression of the Piromyces xylose isomerase gene (XYLA), Pichia stipitis xylulose kinase (XYL3) and genes of the non-oxidative pentose phosphate pathway (PPP). This engineered strain (H131-A3) was used to initialize a three-stage process of evolutionary engineering, through first aerobic and anaerobic sequential batch cultivation followed by growth in a xylose-limited chemostat. The evolved strain H131-A3-AL^CS displayed significantly increased anaerobic growth rate (0.203±0.006 h^?1) and xylose consumption rate (1.866 g g^?1 h^?1) along with high ethanol conversion yield (0.41 g/g). These figures exceed by a significant margin any other performance metrics on xylose utilization and ethanol production by S. cerevisiae reported to-date. Further inverse metabolic engineering based on functional complementation suggested that efficient xylose assimilation is attributed, in part, to the elevated expression level of xylose isomerase, which was accomplished through the multiple-copy integration of XYLA in the chromosome of the evolved strain.     

Triacylglycerol content,productivity and fatty acid profile in Scenedesmus acutus PVUW12

A detailed lipid characterization of Scenedesmus acutus PVUW12, with emphasis on the evaluation of triacylglycerols (TAGs) as a biodiesel feedstock, is presented. When algal cells were grown in nitrogen-free medium (N stress), a lipid increase was detected that was mainly due to TAG accumulation. In situ fluorescence measurements allowed the kinetics and extent of neutral lipid accumulation to be followed. Under N stress, the productivity of total lipids and TAGs increased significantly (80.99 and 63.74 mg L^?1 day^?1, respectively) compared with controls (29.51 and 16.23 mg L^?1 day^?1, respectively). Monounsaturated fatty acids were the major fraction and increased further (49.74 %) in stressed cells, with oleic acid as the most abundant compound (46.97 %). The polyunsaturated fatty acid composition of this algal oil appears to meet the European Standard EN 14214. These results indicate that S. acutus oil meets the requirements for its use as a biodiesel feedstock. Since this strain was also proposed for wastewater bioremediation, this opens up the possibility of its use in an integrated system combined with biofuel production.     

Xylitol production by genetically modified industrial strain of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> using glycerol as co-substrate

Xylitol is commercially used in chewing gum and dental care products as a low calorie sweetener having medicinal properties. Industrial yeast strain of S. cerevisiae was genetically modified to overexpress an endogenous aldose reductase gene GRE3 and a xylose transporter gene SUT1 for the production of xylitol. The recombinant strain (XP-RTK) carried the expression cassettes of both the genes and the G418 resistance marker cassette KanMX integrated into the genome of S. cerevisiae. Short segments from the 5′ and 3′ delta regions of the Ty1 retrotransposons were used as homology regions for integration of the cassettes. Xylitol production by the industrial recombinant strain was evaluated using hemicellulosic hydrolysate of the corn cob with glucose as the cosubstrate. The recombinant strain XP-RTK showed significantly higher xylitol productivity (212 mg L^?1 h^?1) over the control strain XP (81 mg L^?1 h^?1). Glucose was successfully replaced by glycerol as a co-substrate for xylitol production by S. cerevisiae. Strain XP-RTK showed the highest xylitol productivity of 318.6 mg L^?1 h^?1 and titre of 47 g L^?1 of xylitol at 12 g L^?1 initial DCW using glycerol as cosubstrate. The amount of glycerol consumed per amount of xylitol produced (0.47 mol mol^?1) was significantly lower than glucose (23.7 mol mol^?1). Fermentation strategies such as cell recycle and use of the industrial nitrogen sources were demonstrated using hemicellulosic hydrolysate for xylitol production.     

Biotransformation optimization of betulin into betulinic acid production catalysed by cultured Armillaria luteo‐virens Sacc ZJUQH100‐6 cells

Aims: Betulinic acid has attracted attention in terms of its important biological and pharmacological characteristics. The main objective of this work was to optimize the variables of biotransformation process in order to enhance betulinic acid production from betulin catalysed by fungus Armillaria luteo‐virens Sacc ZJUQH100‐6. Methods and Results: Fractional factorial design and response surface methodology were applied to optimize the main parameters that affect betulinic acid production in the growing‐cells system. Results indicated that the addition of Tween 80 and substrate concentration were identified as the significant factors on betulinic acid formation, and the central composite experimental design was then adopted to derive a statistical model for optimizing biotransformation conditions. The optimum conditions were observed at pH 6·0, 0·57% Tween 80, 15 mg l^?1 betulin and at 3 days of stage of inoculation. Conclusions: Under the optimized conditions, the highest productivity of betulinic acid predicted was 9·32%, which increased by 74·53% in comparison with that of the nonoptimized. The verified experiment revealed that the model can well simulate betulin biotransformation. Moreover, the bioconversion of betulin and betulin‐28‐monooxygenase activities was compared between the optimized and the nonoptimized conditions. Significance and Impact of the Study: Current data imply that betulinic acid production from betulin can be effectively enhanced through biotransformation optimization strategy.     

Screening and characterization of Isochrysis strains and optimization of culture conditions for docosahexaenoic acid production

Isochrysis is a genus of marine unicellular microalgae that produces docosahexaenoic acid (DHA, C22:6), a very long chain polyunsaturated fatty acid (PUFA) of significant health and nutritional value. Mass cultivation of Isochrysis for DHA production for human consumption has not been established due to disappointing low DHA productivity obtained from commonly used Isochrysis strains. In this study, 19 natural Isochrysis strains were screened for DHA yields and the results showed that the cellular DHA content ranged from 6.8 to 17.0 % of total fatty acids with the highest DHA content occurring in the exponential growth phase. Isochrysis galbana #153180 exhibited the greatest DHA production potential and was selected for further investigation. The effects of different light intensities, forms, and concentrations of nitrogen, phosphorus, and salinity on growth and DHA production of I. galbana #153180 were studied in a bubble column photobioreactor (PBR). Under favorable culture conditions, I. galbana #153180 contained DHA up to 17.5 % of total fatty acids or 1.7 % of cell dry weight. I. galbana #153180 was further tested in outdoor flat-plate PBRs varying in light path length, starting cell density (SCD), and culture mode (batch versus semicontinuous). When optimized, record high biomass and DHA productivity of I. galbana #153180 of 0.72 g L^?1?day^?1 and 13.6 mg?L^?1?day^?1, or 26.4 g?m^?2?day^?1 and 547.7 mg?m^?2?day^?1, respectively, were obtained, suggesting that I. galbana #153180 may be a desirable strain for commercial production of DHA.     

The betulinic acid production from betulin through biotransformation by fungi

Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important physiological and pharmacological properties. In order to obtain betulinic acid, betulin was submitted to transformation with the selected microorganisms. Betulin biotransformation was carried out with the filamentous fungi Armillaria luteo-virens Sacc QH (ALVS), Aspergillus foetidus ZU-G1 (AF) and Aspergillus oryzae (AO) under seven kinds of transformation condition. As a result of transformation of betulin, A. luteo-virens Sacc QH was the best biocatalyst to produce betulinic acid under the designed conditions. Transformation caused by pre-cultured fungal mycelia, a process designated as G2, was favorable condition for betulin biotransformation as the productivity of betulinic acid was evaluated (>20%). M1 and M2 systems, where the betulin substrate was micro-emulsified in mixtures of Tween 80 and organic solvents, were potential substitutes for G2. The possible pathway of betulin transformation is postulated in this work. The use of fungi and transformation mode described in current work are viable procedures for producing betulinic acid, which is of most importance to replace chemical synthesis ways.     

Improvement of 5-aminolevulinic acid production by Rubrivivax benzoatilyticus PS-5 with self-flocculation by co-fermentation of precursors and volatile fatty acids under pH-controlled conditions

Photosynthetic bacteria are known to utilize volatile fatty acids as a carbon source for growth and product formation. In this study, a new isolate, Rubrivivax benzoatilyticus PS-5, possessing self-flocculation properties, was cultivated in modified glutamate-malate (GM) medium containing glutamate and malate as carbon sources. The effect of acetic acid, propionic acid and butyric acid (at 1–4 g L^?1) as co-substrates and 7.5 mM glycine, 10 mM succinic acid as precursors for 5-aminolevulinic acid (ALA) production from R. benzoatilyticus PS-5 was investigated. Among the volatile fatty acids tested, acetic acid was preferred to butyric acid and propionic acid, with the optimum concentrations of 3 g L^?1, 1 g L^?1 and 3 g L^?1, respectively. The highest ALA production was 169.71 μM, 162.16 μM and 46.18 μM, respectively, while the highest productivity was 2.57 μM h^?1, 2.25 μM h^?1 and 0.96 μM h^?1, respectively. The precursor was consumed completely (100 %) while the assimilation of the acetic acid and butyric acid was 62.50 % and 48.65 %, respectively. Supplementation of propionic acid (at 1–4 g l^?1) had a negative effect on growth and ALA production. To increase production efficiency, the pH-control strategy (at pH 6.0–8.0) during fermentation was tested. The optimum pH was 7.0, giving the maximum ALA production of 286.18 μM and a productivity of 3.97 μM h^?1. These values were 1.68-fold and 1.54-fold higher, respectively, than those under uncontrolled pH conditions.     

Optimization of biomass and fatty acid productivity of Scenedesmus obliquus as a promising microalga for biodiesel production

Nowadays, microalgae are discussed as a promising feedstock for biodiesel production. The present study examines the possibility of enhancement of fatty acid productivity of Scenedesmus obliquus by modifications of the culture medium composition. The effect of different concentrations of sodium bicarbonate, salinity, potassium nitrate, glycerol and sugarcane molasses on the enhancement of biomass and esterified fatty acids production was studied. NaHCO₃ caused an increase in the biomass productivity at low concentrations (0.5 g L^?1), while negatively affected fatty acid productivity at all tested concentrations. Increase of salinity enhanced both biomass and fatty acid productivity. The optimum NaCl concentration and sea water ratio were 0.94 g L^?1 and 25 % which resulted in 56 and 39 % increase in fatty acid productivity, respectively. Nitrogen deficiency showed increase in fatty acid content by 54 % over control but fatty acid productivity was decreased as a result of growth inhibition. Nitrogen-free cultures and cultures treated with ?50 % concentrations of KNO₃ showed 96 and 42 % decrease in EFA productivity, respectively, as compared with the control. Addition of 0.05 and 0.1 M of glycerol increased the biomass productivity by 6 and 5 %, respectively but showed no significant effect on fatty acid productivity as a result of decrease in fatty acid content. Finally, usage of sugarcane molasses stimulated both biomass and fatty acid content. The increase in fatty acid productivity was 32, 65 and 73 % above the control level at 1, 3 and 5 g L^?1 of sugarcane molasses, respectively.     

The fate of linoleic acid on <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> metabolism under aerobic and anaerobic conditions

Introduction

Saccharomyces cerevisiae has been widely used for fermenting food and beverages for over thousands years. Its metabolism together with the substrate composition play an important role in determining the characteristics of the final fermented products. We previously showed that the polyunsaturated fatty acid, linoleic acid, which is present in the grape juice at trace levels, significantly affected the development of aroma compounds of the wines. However, the effect of linoleic acid on the overall cell metabolism of S. cerevisiae is still not clear. Therefore, we aimed to unlock the metabolic response of S. cerevisiae to linoleic acid using metabolomics and isotope labelling experiments.

Methods

We cultured the cells on a minimal mineral medium supplementing them with linoleic acid isomers and 13C-linoleic acid. Both intracellular and extracellular metabolite profiles were determined using gas chromatography coupled to mass spectrometry (GC–MS) to investigate which S. cerevisiae pathways were affected by linoleic acid supplementation.

Results

The utilisation of linoleic acid by S. cerevisiae had a significant impact on the primary carbon metabolism increasing the glucose consumption and the ethanol production under anaerobic condition. The energetic state of the cell was, therefore, affected and the glycolytic pathway, the TCA cycle and the amino acid production were up-regulated. We also observed that linoleic acid was transported into the cell and converted into other fatty acids affecting their profile even under anaerobic condition.

Conclusion

Our data clearly shows that linoleic acid supplementation in growth medium increased glucose consumption and ethanol production by S. cerevisiae under anaerobic condition. We also suggest that S. cerevisiae might be able to perform an alternative anaerobic pathway to β-oxidation, which has not been reported yet.

     

Therapeutic exploration of betulinic acid in chemically induced hypothyroidism

Hypothyroidism is a chronic condition characterized by abnormally low thyroid hormone production. The decreased serum level (>5.1 mIU/l) of thyroid-stimulating hormone (TSH) in blood indicates hypothyroidism. The study was an attempt to access the effect of betulinic acid on chemically induced hypothyroidism in female albino rats. Betulinic acid is a naturally occurring pentacyclic triterpenoid, which has antiretroviral, antimalarial, and anti-inflammatory properties, as well as anticancer potential, by inhibiting topoisomerase. Hypothyroidism was induced in female albino rats using propylthiouracil (PTU) at a dose of 60 μg/kg body weight orally for 1 month. Induction of hypothyroidism was confirmed by increased TSH level. At the end of second month, blood was collected, centrifuged and serum was analyzed for TSH, T3, and T4 level and protocol was terminated by killing of animals. The animals exposed to PTU were treated with pure standard drug thyroxine at a dose of 10 μg/kg of body weight by oral route and the test drug betulinic acid 20 mg/kg by oral route through force feeding in their respective groups. Treatment was carried out for a period of 2 months. Group with PTU-induced hypothyroidism showed an elevation in serum TSH and reduction level, which was restored by the betulinic acid in treated female albino rats. Betulinic acid also reduced the damage caused in the thyroid tissues by PTU, thus minimizing the symptoms of hypothyroidism. Histopathological examinations of the thyroid tissue showed changes in the thyrocytes of PTU-treated group while thyroxine group showed normal thyroid follicles cell architecture and the group treated with betulinic acid also showed marked improvement in the follicles integrity which shows that betulinic acid has some protective activity. This study shows that the betulinic acid has thyroid-enhancing potential by lowering down the TSH levels and reducing the damage caused in the thyroid tissues, thus minimizing the symptoms of hypothyroidism when used anaphylactically in rats.