The aim of this study was to construct Chlorella mutants deficient in chlorophyll synthesis by atmospheric pressure room temperature plasma (ARTP) mutagenesis, and screen novel algal species with very low chlorophyll content which is suitable for protein production by fermentation. Firstly, the lethal rate curve of mixotrophic wild type cells was established by optimizing the mutagenesis treatment time. The mixotrophic cells in early exponential phase were treated by the condition of over 95% lethal rate, and 4 mutants with the visual change of colony color were isolated. Subsequently, the mutants were cultured in shaking flasks heterotrophically for evaluation of their protein production performance. P. ks 4 mutant showed the best performance in Basal medium containing 30 g/L glucose and 5 g/L NaNO₃. The protein content and productivity reached 39.25% dry weight and 1.15 g/(L·d), with an amino acid score of 101.34. The chlorophyll a content decreased 98.78%, whereas chlorophyll b was not detected, and 0.62 mg/g of lutein content made the algal biomass appear golden yellow. This work provides a novel germplasm, the mutant P. ks 4 with high yield and high quality, for alternative protein production by microalgal fermentation.
Chlorella/metabolism* ; Chlorophyll A/metabolism* ; Plant Breeding ; Mutagenesis ; Chlorophyll/metabolism* ; Biomass ; Microalgae

This study was performed to investigate effects of Chlorella vulgaris on lipid metabolism in rats fed high fat diet. Sixty 6-week-old male Wistar rats were divided into two groups; normal diet group and high fat diet group, then the rats in each group were further divided into three subgroups and fed 0%, 5% and 10% (w/w) chlorella-containing diets, respectively, and raised for 9 weeks. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity and total protein and albumin concentration were not different among groups. Serum total lipids and liver TG concentration were significantly lower in 5% and 10% chlorella groups than 0% chlorella group in high fat diet groups (p<0.05). Serum TG, serum total cholesterol, liver total lipid and liver total cholesterol concentrations were significantly lower in 10% chlorella groups than 0% chlorella group in high fat diet groups (p<0.05). Fecal total lipid, TG and total cholesterol excretions were significantly higher in 5% and 10% chlorella groups than 0% chlorella groups in normal diet and high fat diet groups, respectively (p<0.05). These results suggest that Chlorella vulgaris is effective for prevention of dyslipidemia which may be due to the modulation of lipid metabolism and increased fecal excretion of lipid.
Alanine Transaminase ; Animals ; Aspartate Aminotransferases ; Chlorella ; Chlorella vulgaris ; Cholesterol ; Diet ; Diet, High-Fat ; Dyslipidemias ; Humans ; Lipid Metabolism ; Liver ; Male ; Rats ; Rats, Wistar

OBJECTIVE: To study the effects of aerobic exercise combined with chlorella pyrenoidos of disintegrated cell wall on the lipid metabolism in rats with high-fat diet. METHODS: Fifty-five male Wistar rats were subjected to adaptive feeding for 4 days and weight-free swimming training for 3 days, 20 min/d. After eliminating 5 rats that were not suitable for swimming training, the other rats were randomly divided into 5 groups according to their body weight:control group (C group), high fat diet group (H group), high-fat diet + chlorella group(HC group), high fat diet + aerobic exercise group (HM group), high fat diet + chlorella + aerobic exercise group (HMC group), 10 in each group. The HM and HMC group were subjected to 60 min/d swimming training for 6 weeks with non-weight-bearing. Group C were fed regular diet. The other groups were fed with high-fat diet, the rats in group HC and HMC were intragastrically treated with chlorella pyrenoidos of disintegrated cell wall at the dose of 3.9 g/(kg·d), the volume was 5 ml/kg, and the other groups are given equivalent saline. The Lee's index and biochemical indexes of blood and liver were measured after 6 weeks. RESULTS: Compared with group C, Lee's index, serum levels of free fatty acids(FFA), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-c), liver FFA and interleukin-10 (IL-10) were increased significantly (<0.01), the serum level of high-density lipoprotein cholesterol (HDL-c) was decreased significantly (<0.01) in group H. Compared with group H, Lee's index, serum FFA, IL-6, TNF-α, TC, TG, LDL-c, liver FFA and IL-10 were decreased significantly (<0.05 or <0.01), serum level of HDL-c was increased significantly (<0.05 or <0.01) in group HC, HM and HMC. Compared with group HC and HM, Lee's index, serum FFA, IL-6, TNF-α, TC, TG, LDL-c, liver FFA and IL-10 were decreased significantly (<0.05), serum level of HDL-c was increased significantly (<0.05) in group HMC. CONCLUSIONS Aerobic exercise and chlorella pyrenoidos of disintegrated cell wall can improve lipid metabolism in rats with high-fat diet and reduce the lipid toxicity caused by obesity. Joint intervention is more effective than single intervention.
Animals ; Cell Wall ; Chlorella ; Diet, High-Fat ; Lipid Metabolism ; Male ; Physical Conditioning, Animal ; Rats ; Rats, Wistar

We studied the hydrogen evolution (HE) of green alga Chlorella pyrenoidosa grown in normal (nutrients sufficient) media and nitrogen, manganese or sulfur deprived medium. The results showed that photo-hydrogen evolution could occur under all conditions herein before, but the efficiency of HE was maximum under nitrogen deprivation, and the total hydrogen yield was 88.613 microL H2/mg Chla, which was 4.61, 1.92, 3.63 times of control, manganese deprivation, sulfur deprivation groups, respectively. We also measured the growth, the photosynthesis and respiration of the alga. The data demonstrated that manganese deprivation had less influence than nitrogen and sulfur deprivation on the growth, the photosynthesis and respiration of C. pyrenoidosa. Compared with the normal (nutrients sufficient), manganese and sulfur deprivation inhibited the photosynthesis and growth of the alga while bringing small impact on respiration. Nitrogen deprivation, however, greatly restrained the photosynthesis and growth while enhancing the respiration. Those data provide clues for the further study on both the conditions optimization and mechanism of hydrogen evolution.
Chlorella ; growth & development ; metabolism ; Hydrogen ; analysis ; metabolism ; Manganese ; analysis ; metabolism ; Nitrogen ; analysis ; metabolism ; Photosynthesis ; Sulfur ; analysis ; metabolism

The aim of this study was to establish a novel technology using microalgae for NO₃⁻ removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO₃⁻ assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO₃⁻ assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d⁻¹). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO₃⁻ assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.
Algal Proteins ; biosynthesis ; Biomass ; Chlorella ; Nitrates ; isolation & purification ; metabolism ; Nitrogen ; metabolism ; Waste Water ; chemistry ; Water Purification ; methods

Using 50% biogas slurry as basic medium, we investigated the effect of pH on the growth and lipid accumulation of Chlorella vulgaris. Setting two-group experiments, one was only control the initial medium pH, the initial pH was set at 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5, respectively. One was control the medium pH constant, set constant pH at 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5, respectively. Using HCl and NaOH regulated the pH. Results showed that algae Chlorella vulgaris grows better at pH 6.5 and 7.0, accumulate the lipid at pH 7.0-8.5, so the optimal pH for the growth and the lipid accumulation of Chlorella vulgaris was 7.0. The average removal rate of nitrate from biogas slurry was 95%, phosphate was 97%.
Biofuels ; Chlorella vulgaris ; growth & development ; metabolism ; Culture Media ; Culture Techniques ; methods ; Fermentation ; Hydrogen-Ion Concentration ; Lipids ; analysis ; biosynthesis

Photoautotrophic cultivation with heterotrophic cells as seeds (heterotrophic cells/photoautotrophic cultivation) is an effective way for the development of microalgal biofuel, but its development potential from the point of process optimization has not been investigated in literatures. To evaluate this, the optimizations of medium and culture conditions for Chlorella ellipsoidea were studied. In the heterotrophic stage, the biomass concentration reached 11.04 g/L with the optimized medium in flask, which were 28.0% higher than that with the original medium, and the biomass concentration reached 73.89 g/L in 5-L fermenter. In the photoautotrophic stage, the culture medium and conditions were studied in a 2-L column photobioreactor. The maximum biomass concentration, lipid content and lipid productivity reached 1.62 g/L, 36.34% and 6.1 mg/(L·h) under the optimal photoautotrophic conditions. The lipids were mainly composed of C16-C18 fatty acids, which were raw material suitable for biodiesel. After optimization, heterotrophic cells/photoautotrophic cultivation can significantly improve the capacity of biofuel production by Chlorella ellipsoidea, this method is also expected to be an efficient way for the cultivation of other microalgae that can grow heterotrophically.
Biofuels ; Biomass ; Cell Culture Techniques ; Chlorella ; metabolism ; Culture Media ; Fatty Acids ; biosynthesis ; Heterotrophic Processes ; Lipids ; biosynthesis ; Photobioreactors

We studied the effects of three inorganic carbon sources, Na2CO3, NaHCO3 and CO2, and their initial concentrations on lipid production of Chlorella vulgaris. Chlorella vulgaris could utilize Na2CO3, NaHCO3 and CO2 to produce lipids. After 10-day cultivation with each of the three inorganic carbon sources, lipid yield of Chlorella vulgaris reached its peak with the concentration increase of the inorganic carbon source, but dropped again by further increase of the concentration. The pH value of the culture medium for Chlorella vulgaris increased after the cultivation on inorganic carbon source. The optimal concentration of both Na2CO3 and NaHCO3 was 40 mmol/L, and their corresponding biomass dry weight was 0.52 g/L and 0.67 g/L with their corresponding lipid yield 0.19 g/L and 0.22 g/L. When the concentration of CO2 was 6%, Chlorella vulgaris grew the fastest and its biomass dry weight was 2.42 g/L with the highest lipid yield of 0.72 g/L. When the concentration of CO2 was too low, the supply of inorganic carbon was insufficient and lipid yield was low. A too high concentration of CO2 caused a low pH and lipid accumulation was inhibited. Na2CO3 and NaHCO3 were more favorable for Chlorella vulgaris to accumulate unsaturated fatty acids than that of CO2.
Biofuels ; Carbon ; metabolism ; Carbon Dioxide ; pharmacology ; Carbonates ; pharmacology ; Chlorella vulgaris ; growth & development ; metabolism ; Culture Media ; Culture Techniques ; methods ; Lipids ; biosynthesis ; Sodium Bicarbonate ; pharmacology

Chlorella vulgaris (CV) has been reported to have antioxidant and anticancer properties. We evaluated the effect of CV on apoptotic regulator protein expression in liver cancer-induced rats. Male Wistar rats (200~250 g) were divided into eight groups: control group (normal diet), CDE group (choline deficient diet supplemented with ethionine in drinking water to induce hepatocarcinogenesis), CV groups with three different doses of CV (50, 150, and 300 mg/kg body weight), and CDE groups treated with different doses of CV (50, 150, and 300 mg/kg body weight). Rats were sacrificed at various weeks and liver tissues were embedded in paraffin blocks for immunohistochemistry studies. CV, at increasing doses, decreased the expression of anti-apoptotic protein, Bcl-2, but increased the expression of pro-apoptotic protein, caspase 8, in CDE rats, which was correlated with decreased hepatocytes proliferation and increased apoptosis as determined by bromodeoxy-uridine (BrdU) labeling and terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) assay, respectively. Our study shows that CV has definite chemopreventive effect by inducing apoptosis via decreasing the expression of Bcl-2 and increasing the expression of caspase 8 in hepatocarcinogenesis-induced rats.
Animals ; Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; metabolism ; Cell Proliferation ; drug effects ; Chlorella vulgaris ; chemistry ; Dietary Supplements ; Liver Neoplasms ; diet therapy ; metabolism ; pathology ; Male ; Plant Extracts ; administration & dosage ; Rats ; Rats, Wistar ; Treatment Outcome