Effects of ScRgt1-Like DNA-binding transcription factor SpRgt1 (SPCC320.03) on Hexose transporters gene expression in Schizosaccharomyces pombe.

Glucose, which plays an essential role in carbon and energy metabolism in eukaryotes, is vital in directing various energy-consuming cellular processes. In S. cerevisiae, transcription factors involved in regulating hexose transporters and their mechanisms of action under different carbon sources were revealed in detail. However, there is limited information on these processes in S. pombe. In this study, the effect of SPCC320.03 (named SpRgt1), the ortholog of ScRgt1 whose molecular mechanism is known in detail in S. cerevisiae, on the transcriptional regulation of hexose transporters (ght1-8) dependent on different carbon sources was investigated. We measured the transcript levels of ght1-8 using the qPCR technique and performed relative evaluation in S. pombe strains (parental, rgt1 deleted mutant, rgt1 overexpressed, and vectoral rgt1 carrying mutant). We aimed to investigate the transcriptional changes caused by the protein product of the rgt1 (SPCC320.03) gene in terms of ght1-8 genes in strains that are grown in different carbon sources (2% glucose, 2% glycerol + 0.1% glucose, and 2% gluconate). Here, we show that SpRgt1 is involved in the regulation of the ght3, ght4, ght6, and ght7 genes but that the ght1, ght2, ght5, and ght8 gene expression vary depending on carbon sources, independently of SpRgt1.

How do the carbon and nitrogen sources affect the synthesis of ß-(1,3/1,6)-glucan, its structure and the susceptibility of Candida utilis yeast cells to immunolabelling with ß-(1,3)-glucan monoclonal antibodies?

BACKGROUND: The need to limit antibiotic therapy due to the spreading resistance of pathogenic microorganisms to these medicinal substances stimulates research on new therapeutic agents, including the treatment and prevention of animal diseases. This is one of the goals of the European Green Deal and the Farm-To-Fork strategy. Yeast biomass with an appropriate composition and exposure of cell wall polysaccharides could constitute a functional feed additive in precision animal nutrition, naturally stimulating the immune system to fight infections. RESULTS: The results of the research carried out in this study showed that the composition of Candida utilis ATCC 9950 yeast biomass differed depending on growth medium, considering especially the content of ß-(1,3/1,6)-glucan, α-glucan, and trehalose. The highest ß-(1,3/1,6)-glucan content was observed after cultivation in deproteinated potato juice water (DPJW) as a nitrogen source and glycerol as a carbon source. Isolation of the polysaccharide from yeast biomass confirmed the highest yield of ß-(1,3/1,6)-glucan after cultivation in indicated medium. The differences in the susceptibility of ß-(1,3)-glucan localized in cells to interaction with specific ß-(1,3)-glucan antibody was noted depending on the culture conditions. The polymer in cells from the DPJW supplemented with glycerol and galactose were labelled with monoclonal antibodies with highest intensity, interestingly being less susceptible to such an interaction after cell multiplication in medium with glycerol as carbon source and yeast extract plus peptone as a nitrogen source. CONCLUSIONS: Obtained results confirmed differences in the structure of the ß-(1,3/1,6)-glucan polymers considering side-chain length and branching frequency, as well as in quantity of ß-(1,3)- and ß-(1,6)-chains, however, no visible relationship was observed between the structural characteristics of the isolated polymers and its susceptibility to immunolabeling in whole cells. Presumably, other outer surface components and molecules can mask, shield, protect, or hide epitopes from antibodies. ß-(1,3)-Glucan was more intensely recognized by monoclonal antibody in cells with lower trehalose and glycogen content. This suggests the need to cultivate yeast biomass under appropriate conditions to fulfil possible therapeutic functions. However, our in vitro findings should be confirmed in further studies using tissue or animal models.

Carbon Source in Tertiary Denitrification Regulates Dissolved Organic Nitrogen in Wastewater Effluent.

With global eutrophication and increasingly stringent nitrogen discharge restrictions, dissolved organic nitrogen (DON) holds considerable potential to upgrade advanced wastewater denitrification because of its large contribution to low-nitrogen effluents and stronger stimulation effect for algae. Here, we show that DON from the postdenitrification systems dominates effluent eutrophication potential under different carbon sources. Methanol resulted in significantly lower DON concentrations (0.84 ± 0.03 mg/L) compared with the total nitrogen removal-preferred acetate (1.11 ± 0.02 mg/L) (p < 0.05, ANOVA). With our well-developed mathematical model (R2 = 0.867-0.958), produced DON instead of shared (persist in both influent and effluent) and/or removed DON was identified as the key component for effluent DON variation (Pearson r = 0.992, p < 0.01). The partial least-squares path modeling analysis showed that it is the microbial community (r = 0.947, p < 0.01) rather than the predicted metabolic functions (r = 0.040, p > 0.1) that affected produced DON. Carbon sources rebuild the microorganism-DON interaction by affecting the structure of microbial communities with different abilities to generate and recapture produced DON to finally regulate effluent DON. This study revalues the importance of carbon source selection and overturns the current rationality of pursuing only the total nitrogen removal efficiency by emphasizing DON.

Machine Learning-Assisted Optimization of Mixed Carbon Source Compositions for High-Performance Denitrification.

Appropriate mixed carbon sources have great potential to enhance denitrification efficiency and reduce operational costs in municipal wastewater treatment plants (WWTPs). However, traditional methods struggle to efficiently select the optimal mixture due to the variety of compositions. Herein, we developed a machine learning-assisted high-throughput method enabling WWTPs to rapidly identify and optimize mixed carbon sources. Taking a local WWTP as an example, a mixed carbon source denitrification data set was established via a high-throughput method and employed to train a machine learning model. The composition of carbon sources and the types of inoculated sludge served as input variables. The XGBoost algorithm was employed to predict the total nitrogen removal rate and microbial growth, thereby aiding in the assessment of the denitrification potential. The predicted carbon sources exhibited an enhanced denitrification potential over single carbon sources in both kinetic experiments and long-term reactor operations. Model feature analysis shows that the cumulative effect and interaction among individual carbon sources in a mixture significantly enhance the overall denitrification potential. Metagenomic analysis reveals that the mixed carbon sources increased the diversity and complexity of denitrifying bacterial ecological networks in WWTPs. This work offers an efficient method for WWTPs to optimize mixed carbon source compositions and provides new insights into the mechanism behind enhanced denitrification under a supply of multiple carbon sources.

Metabolomic reveals the responses of sludge properties and microbial communities to high nitrite stress in denitrifying phosphorus removal systems.

Nitrite, as an electron acceptor, plays a good role in denitrifying phosphorus removal (DPR); however, high nitrite concentration has adverse affects on sludge performance. We investigated the precise mechanisms of responses of sludge to high nitrite stress, including surface characteristics, intracellular and extracellular components, microbial and metabolic responses. When the nitrite stress reached 90 mg/L, the sludge settling performance was improved, but the activated sludge was aging. FTIR and XPS analysis revealed a significant increase in the hydrophobicity of the sludge, resulting in improve settling performance. However, the intracellular carbon sources synthesis was inhibited. In addition, the components in the tightly bound extracellular polymeric substances (TB-EPS) of sludge were significantly reduced and indicated the disturb of metabolism. Notably, Exiguobacterium emerged as a new genus when face high nitrite stress that could maintaining survival in hostile environments. Moreover, metabolomic analysis demonstrated strong biological response to nitrite stress further supported above results that include the inhibited of carbohydrate and amino acid metabolism. More importantly, some lipids (PS, PA, LysoPA, LysoPC and LysoPE) were significantly upregulated that related enhanced membrane lipid remodeling. The comprehensive analyses provide novel insights into the high nitrite stress responses mechanisms in activated sludge systems.

Blocking the utilization of carbon sources via two pathways to induce tumor starvation for cancer treatment.

Glucose oxidase (GOx) is often used to starvation therapy. However, only consuming glucose cannot completely block the energy metabolism of tumor cells. Lactate can support tumor cell survival in the absence of glucose. Here, we constructed a nanoplatform (Met@HMnO2-GOx/HA) that can deplete glucose while inhibiting the compensatory use of lactate by cells to enhance the effect of tumor starvation therapy. GOx can catalyze glucose into gluconic acid and H2O2, and then HMnO2 catalyzes H2O2 into O2 to compensate for the oxygen consumed by GOx, allowing the reaction to proceed sustainably. Furthermore, metformin (Met) can inhibit the conversion of lactate to pyruvate in a redox-dependent manner and reduce the utilization of lactate by tumor cells. Met@HMnO2-GOx/HA nanoparticles maximize the efficacy of tumor starvation therapy by simultaneously inhibiting cellular utilization of two carbon sources. Therefore, this platform is expected to provide new strategies for tumor treatment.

External carbon source as a viable tool for controlling antibiotics and antibiotic resistance genes (ARGs) in effluent: Influence on antibiotic removal and ARGs dissemination.

Fluoroquinolone antibiotics and antibiotic resistance genes (ARGs) regarded as emerging contaminants were poorly removed in conventional wastewater treatment plants (WWTPs). Nitrogen-containing heterocyclic organics were found to be biodegraded through denitrification co-metabolism. The feasibility to enhance antibiotics removal efficiency in WWTPs through denitrification co-metabolism needs to be further verified. Meanwhile, due to significant correlation between ARGs profiles and nitrogen removal that was previously observed, the dissemination of ARGs during denitrification was worthy of in-depth understanding. Herein, the antibiotic removal and ARGs dissemination in denitrification co-metabolism condition were investigated with different denitrifying consortiums that acclimated under different conditions in terms of carbon source and the exposure of Ofloxacin (OFL). The results suggest that the removal of OFL can be enhanced by the denitrification co-metabolism. The tolerance to OFL is different among various denitrifying communities. For the denitrifying consortiums acclimated with methanol, long-term exposure to trace OFL (1 µg/L) could reduce the capabilities of removal and tolerance to OFL. On the contrary, those acclimated with sodium acetate (NaAc), the capabilities of removal and tolerance to OFL, were enhanced by long-term exposure to trace OFL. According to the quantitative determination to 384 target genes with high-throughput quantitative PCR, the abundance of ARGs in consortiums greatly increased when exposed to OFL at the concentration of comparable to sewage, which was also much larger than that acclimated with methanol. It can be confirmed and supported by DNA sequencing results that the antibiotic removal and the dissemination of ARGs were determined by microbial community that could be shaped with carbon source. These conclusions suggest that selecting the right external carbon source can be a useful strategy for WWTPs to control antibiotics and ARGs in the effluent. From a new perspective on mitigating ARGs dissemination, NaAc was not an appropriate carbon source.

Implications in the production of defossilized methanol: A study on carbon sources.

The transition of the current fossil based chemical industry to a carbon-neutral industry can be done by the substitution of fossil carbon for defossilized carbon in the production of base chemicals. Methanol is one of the seven base chemicals, which could be used to produce other base chemicals (light olefins and aromatics). In this research, we evaluated the synthesis of methanol based on defossilized carbon sources (maize, waste biomass, direct air capture of CO2 (DAC), and CO2 from the cement industry) by considering carbon source availability, energy, water, and land demand. This evaluation was based on a carbon balance for each of the carbon sources. Our results show that maize, waste biomass, and CO2 cement could supply 0.7, 2, 15 times the carbon demand for methanol respectively. Regarding the energy demand maize, waste biomass, DAC, and CO2 from cement demand 25, 21, 48, and 45GJtonMeOH separately. The demand for water is 5300, 220, 8, and 8m3tonMeOH. And lastly, land demand was estimated to 1031, 36, 83, and 77m2tonMeOH per carbon source. The high-demanding-resource production of defossilized methanol is dependent on the availability of resources per location. Therefore, we analyzed the production of defossilized methanol in the Netherlands, Saudi Arabia, China, and the USA. China is the only country where CO2 from the cement industry could provide all the demand of carbon. But as we envision society becoming carbon neutral, CO2 from the cement industry would diminish in time, as a consequence, it would not be sufficient to supply the demand for carbon. DAC would be the only source able to provide the demand for defossilized carbon.

Simultaneous Formate and Syngas Conversion Boosts Growth and Product Formation by Clostridium ragsdalei.

Electrocatalytic CO2 reduction to CO and formate can be coupled to gas fermentation with anaerobic microorganisms. In combination with a competing hydrogen evolution reaction in the cathode in aqueous medium, the in situ, electrocatalytic produced syngas components can be converted by an acetogenic bacterium, such as Clostridium ragsdalei, into acetate, ethanol, and 2,3-butanediol. In order to study the simultaneous conversion of CO, CO2, and formate together with H2 with C. ragsdalei, fed-batch processes were conducted with continuous gassing using a fully controlled stirred tank bioreactor. Formate was added continuously, and various initial CO partial pressures (pCO0) were applied. C. ragsdalei utilized CO as the favored substrate for growth and product formation, but below a partial pressure of 30 mbar CO in the bioreactor, a simultaneous CO2/H2 conversion was observed. Formate supplementation enabled 20-50% higher growth rates independent of the partial pressure of CO and improved the acetate and 2,3-butanediol production. Finally, the reaction conditions were identified, allowing the parallel CO, CO2, formate, and H2 consumption with C. ragsdalei at a limiting CO partial pressure below 30 mbar, pH 5.5, n = 1200 min-1, and T = 32 °C. Thus, improved carbon and electron conversion is possible to establish efficient and sustainable processes with acetogenic bacteria, as shown in the example of C. ragsdalei.

Efficient de novo production of bioactive cordycepin by Aspergillus oryzae using a food-grade expression platform.

BACKGROUND: Cordycepin (3'-deoxyadenosine) is an important bioactive compound in medical and healthcare markets. The drawbacks of commercial cordycepin production using Cordyceps spp. include long cultivation periods and low cordycepin yields. To overcome these limitations and meet the increasing market demand, the efficient production of cordycepin by the GRAS-status Aspergillus oryzae strain using a synthetic biology approach was developed in this study. RESULTS: An engineered strain of A. oryzae capable of cordycepin production was successfully constructed by overexpressing two metabolic genes (cns1 and cns2) involved in cordycepin biosynthesis under the control of constitutive promoters. Investigation of the flexibility of carbon utilization for cordycepin production by the engineered A. oryzae strain revealed that it was able to utilize C6-, C5-, and C12-sugars as carbon sources, with glucose being the best carbon source for cordycepin production. High cordycepin productivity (564.64 ± 9.59 mg/L/d) was acquired by optimizing the submerged fermentation conditions. CONCLUSIONS: This study demonstrates a powerful production platform for bioactive cordycepin production by A. oryzae using a synthetic biology approach. An efficient and cost-effective fermentation process for cordycepin production using an engineered strain was established, offering a powerful alternative source for further upscaling.

Macrofaunal control of microbial community structure in continental margin sediments.

Through a process called "bioturbation," burrowing macrofauna have altered the seafloor habitat and modified global carbon cycling since the Cambrian. However, the impact of macrofauna on the community structure of microorganisms is poorly understood. Here, we show that microbial communities across bioturbated, but geochemically and sedimentologically divergent, continental margin sites are highly similar but differ clearly from those in nonbioturbated surface and underlying subsurface sediments. Solid- and solute-phase geochemical analyses combined with modeled bioturbation activities reveal that dissolved O2 introduction by burrow ventilation is the major driver of archaeal community structure. By contrast, solid-phase reworking, which regulates the distribution of fresh, algal organic matter, is the main control of bacterial community structure. In nonbioturbated surface sediments and in subsurface sediments, bacterial and archaeal communities are more divergent between locations and appear mainly driven by site-specific differences in organic carbon sources.

Effect of thermal hydrolyzed sludge filtrate as an external carbon source on biological nutrient removal performance of A2/O system.

Thermal hydrolyzed sludge filtrate (THSF) rich in biodegradable organics could be a promising external carbon source for biological nutrient removal (BNR). The use of THSF can effectively reduce wastewater treatment plants operating costs and recover bioresources and bioenergy from the waste activated sludge. In this study, the effect of THSF on the BNR process was investigated using a lab-scale anaerobic/anoxic/oxic (A2/O) system. Total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 74.26 ± 3.36% and 92.20 ± 3.13% at a 0.3% dosing ratio were achieved, respectively. Moreover, 20.42% of the chemical oxygen demand (COD) contained in THSF contributed to denitrification, enhancing nitrogen removal efficiency from 55.30 to 74.26%. However, the effluent COD increased by approximately 36.80%, due to 18.39% of the COD contained in THSF discharged with effluent. In addition, the maximum denitrification rate was approximately 16.01 mg N g VSS-1 h-1, while the nitrification rate was not significantly affected by THSF. Nitrosomonas, a common chemoautotrophic nitrifier, was not detected after the introduction of THSF. The aerobic denitrifier Rubellimicrobium was stimulated, and its relative abundance increased from 0.16 to 3.03%. Moreover, the relative abundance of Dechloromonas was 3.93%, indicating that the denitrifying phosphorus removal process was enhanced. This study proposes an engineering application route of THSF, and the chemical phosphate removal pretreatment might be a means to suppress the phosphate recirculation.

Multi-scenario simulation of carbon budget balance in arid and semi-arid regions.

The carbon budget has emerged as a central focus in global carbon cycle research. The limited understanding of carbon budget balance dynamics has led to an increasing imbalance between ecological and socio-economic benefits. Building upon a comprehensive analysis of carbon storage and emission in Lanzhou from 2000 to 2020, this study develops a novel deep learning model (CNN-LSTM) to simulate carbon budget under various scenarios from 2030 to 2050. Additionally, scientifically grounded recommendations for carbon compensation are provided. The results demonstrate several key findings: (1) The deep learning model exhibits outstanding performance, with an average overall accuracy exceeding 0.93. The coupled model outperforms individual models, underscoring the significance and necessity of incorporating both temporal and spatial features in land use simulation. (2) Under the ecological protection redline scenario from 2030 to 2050, a noteworthy augmentation in carbon storage and a proficient constraint on carbon emissions are observed. This substantiates the effectiveness of ecological protection interventions. (3) Carbon compensation payment areas are predominantly concentrated in built-up land, with the extent of these areas expanding over time. (4) The disparities in carbon balance effects of forest were more conspicuous than that of built-up land across diverse temporal and scenarios.

Production of 3-Hydroxypropionic Acid from Renewable Substrates by Metabolically Engineered Microorganisms: A Review.

3-Hydroxypropionic acid (3-HP) is a platform chemical with a wide range of existing and potential applications, including the production of poly(3-hydroxypropionate) (P-3HP), a biodegradable plastic. The microbial synthesis of 3-HP has attracted significant attention in recent years due to its green and sustainable properties. In this paper, we provide an overview of the microbial synthesis of 3-HP from four major aspects, including the main 3-HP biosynthesis pathways and chassis strains used for the construction of microbial cell factories, the major carbon sources used for 3-HP production, and fermentation processes. Recent advances in the biosynthesis of 3-HP and related metabolic engineering strategies are also summarized. Finally, this article provides insights into the future direction of 3-HP biosynthesis.

Agricultural carbon emissions in Zhejiang Province, China (2001-2020): changing trends, influencing factors, and has it achieved synergy with food security and economic development?

Given the huge carbon footprint of agricultural activities, reduction in agricultural carbon emission (ACE) is important to achieve China's carbon peaking and carbon neutrality goals, but it may affect agricultural food security and economic development. Therefore, it is important for scientific carbon reduction measures to understand the multi-year trends and the influencing factors of ACE, and clarify whether the process of ACE affects food security and economic development. This study analyzed the trends of total ACE and ACE caused by different agricultural carbon sources (ACS) from 2001 to 2020 in Zhejiang Province, then we revealed the main influencing factors of ACE based on the logarithmic mean Divisia index (LMDI) model and dissected the relationship between ACE and food security and economic development. Results show that the total ACE fluctuated from 6.10 Mt in 2001 to 3.93 Mt in 2020, and the process included a decrease in 2001-2003 and 2005-2020 and an increase in 2003-2005. The decrease in ACE, from 2001 to 2014, was mainly due to the decline in rice acreage, which contributed 90.38%; from 2014 to 2020, it was by the reduction in the use of fertilizer, diesel, and pesticide, which contributed 83.9%. As drivers, agricultural economic development effect and total population size effect drove 4.25 and 1.54 Mt of ACE, respectively. As inhibitors, planting structure effect, technology development effect, and population structure effect inhibited 3.12, 2.11, and 2.74 Mt of ACE, respectively. With the reduction of ACE, the agricultural economy continued to grow, but the food security situation was pessimistic, indicating that ACE reduction has achieved synergy with economic development, but not with food security.

Effect of Different Carbons on Lipid Production and SNF1 Transcription in Mucor Circinelloides.

Sucrose non-fermenting 1 (SNF1) protein kinase plays an important role in the utilization of selective carbon sources and regulation of lipid metabolism. In order to further explore the function of SNF1 in regulating lipid accumulation by responding nutritional signals from non-glucose carbon sources, in the present study, the lipid production and SNF1 transcriptional levels of Mucor circinelloides were analyzed and compared on different carbon sources. The results indicated that M. circinelloides could effectively utilize some secondary metabolic carbon sources of monosaccharides and disaccharides for growth and lipids production, such as fructose, maltose and galactose. Snf-ß subunit was associated with the regulation of lipid metabolism in response to nutritional signals from different carbon sources. This is the first report on the transcriptional analysis of SNF1 subunits on different carbons metabolism in oleaginous filamentous fungi. This research has suggested that genetic engineering of SNF1 subunits will alter the lipid production of M. circinelloides from alternative carbon sources. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01070-z.

Impact of Carbon Source Supplementations on Pseudomonas aeruginosa Physiology.

Pseudomonas aeruginosa is an opportunistic pathogen highly resistant to a wide range of antimicrobial agents, making its infections very difficult to treat. Since microorganisms need to perpetually adapt to their surrounding environment, understanding the effect of carbon sources on P. aeruginosa physiology is therefore essential to avoid increasing drug-resistance and better fight this pathogen. By a global proteomic approach and phenotypic assays, we investigated the impact of various carbon source supplementations (glucose, glutamate, succinate, and citrate) on the physiology of the P. aeruginosa PA14 strain. A total of 581 proteins were identified as differentially expressed in the 4 conditions. Most of them were more abundant in citrate supplementation and were involved in virulence, motility, biofilm development, and antibiotic resistance. Phenotypic assays were performed to check these hypotheses. By coupling all this data, we highlight the importance of the environment in which the bacterium evolves on its metabolism, and thus the necessity to better understand the metabolic pathways implied in its adaptative response according to the nutrient availability.

Metabolic flexibility and extensive adaptability governing multiple drug resistance and enhanced virulence in Candida albicans.

Commensal fungus-Candida albicans turn pathogenic during the compromised immunity of the host, causing infections ranging from superficial mucosal to dreadful systemic ones. C. albicans has evolved various adaptive measures which collectively contribute towards its enhanced virulence. Among fitness attributes, metabolic flexibility and vigorous stress response are essential for its pathogenicity and virulence. Metabolic flexibility provides a means for nutrient assimilation and growth in diverse host microenvironments and reduces the vulnerability of the pathogen to various antifungals besides evading host immune response(s). Inside the host micro-environments, C. albicans efficiently utilizes the multiple fermentable and non-fermentable carbon sources to sustain and proliferate in glucose deficit conditions. The utilization of alternative carbon sources further highlights the importance of understanding these pathways as the attractive and potential therapeutic target. A thorough understanding of metabolic flexibility and adaptation to environmental stresses is warranted to decipher in-depth insights into virulence and molecular mechanisms of fungal pathogenicity. In this review, we have attempted to provide a detailed and recent understanding of some key aspects of fungal biology. Particular focus will be placed on processes like nutrient assimilation and utilization, metabolic adaptability, virulence factors, and host immune response in C. albicans leading to its enhanced pathogenicity.

Recent advances, challenges and metabolic engineering strategies in the biosynthesis of 3-hydroxypropionic acid.

As an attractive and valuable platform chemical, 3-hydroxypropionic acid (3-HP) can be used to produce a variety of industrially important commodity chemicals and biodegradable polymers. Moreover, the biosynthesis of 3-HP has drawn much attention in recent years due to its sustainability and environmental friendliness. Here, we focus on recent advances, challenges, and metabolic engineering strategies in the biosynthesis of 3-HP. While glucose and glycerol are major carbon sources for its production of 3-HP via microbial fermentation, other carbon sources have also been explored. To increase yield and titer, synthetic biology and metabolic engineering strategies have been explored, including modifying pathway enzymes, eliminating flux blockages due to byproduct synthesis, eliminating toxic byproducts, and optimizing via genome-scale models. This review also provides insights on future directions for 3-HP biosynthesis.

Effects of organic carbon sources on growth and oil accumulation by Desmodesmus subspicatus LC172266 under mixotrophic condition.

Energy crisis and environmental sustainability have attracted global attention to microalgal biofuels. The present study investigated the impact of organic carbon sources on growth and bio-oil accumulation by an oleaginous microalga Desmodesmus subspicatus LC172266 under mixotrophic culture condition. Glucose and glycerol supported higher growth rates and lipid productivities than sucrose, fructose, mannitol and acetate. Each of the organic carbon source tested supported significantly (P < 0.05) higher growth rates and lipid productivities than the photoautotrophic culture (without organic carbon source). The lipid productivity obtained with a mixture of optima concentrations of glucose and glycerol (5.0 gL-1 glycerol + 10.0 gL-1glucose) (0.14875 ± 0.002 g/L/day) was about 25% and 66% higher than the values obtained with only 10.0 gL-1glucose and 5.0 gL-1glycerol, respectively. When a batch culture with 5gL-1glycerol was fed with 0.5 gL-1glucose daily the cell growth and lipid productivity were lower than the values obtained in a batch culture with a mixture of glucose and glycerol. The lipid productivity obtained in a 4-L photobioreactor was 94% (0.217 gL-1 day-1), higher than the value obtained in a flask culture with 10.0 g/Lglucose (0.112 gL-1 day-1) and 46% higher than the value obtained in a flask culture with 5.0 gL-1glycerol (0.086 gL-1 day-1).