Changliang Nie

The effects of combined agricultural phytohormones on the growth, carbon partitioning and cell morphology of two screened algae

Applying phytohormones has been considered a promising way to increase lipid productivity of microalgae recently. Eight dosages of auxin phytohormones were tested to exploit the effects and mechanism of such stimulants on microalgae. The optimal one was 20mgL-1, leading to an increase in biomass concentration of 59.3% for Scenedesmus sp. SDEC-8 and 76.6% for Chlorella sorokiniana SDEC-18, meanwhile the lipid content rose from 18.74% to 56.17% (SDEC-8) and from 19.69% to 55.76% (SDEC-18). Proton pumps were activated by the stimulants, causing excretion of H+, which resulted in pH decline and a favorable condition for growth. Pigments changes implied that hormones strengthened the dark reactions of photosynthesis. Auxin addition led to a 3μm increase in diameter for C. sorokiniana SDEC-18 and altered the cellular pattern of Scenedesmus sp. SDEC-8, which improved the cells elongation. Therefore, supplement of auxin phytohormones simultaneously increased the viability and lipid production of microalgae.

The effect of algae species on the bioelectricity and biodiesel generation through open-air cathode microbial fuel cell with kitchen waste anaerobically digested effluent as substrate

Five strains algae (Golenkinia sp. SDEC-16, Chlorella vulgaris, Selenastrum capricornutum, Scenedesmus SDEC-8 and Scenedesmus SDEC-13) were screened as an effective way to promote recover electricity from MFC for kitchen waste anaerobically digested effluent (KWADE) treatment. The highest OCV, power density, biomass concentration and total lipid content were obtained with Golenkinia sp. SDEC-16 as the co-inoculum, which were 170mV, 6255mWm(-3), 325mgL(-1) and 38%, respectively. Characteristics of the organics in KWADE were analyzed, and the result showed that the hydrophilic and acidic fractions were more readily degraded, compared to the neutral fractions during the operation. Maximum COD and TN removal efficiency were 43.59% and 37.39% when inoculated with Golenkinia sp. SDEC-16, which were roughly 3.22 and 3.04 times higher than that of S. capricornutum. This study demonstrated that Golenkinia sp. SDEC-16 was a promising species for bioelectricity generation, lipid production and KWADE treatment.

Phytohormone addition coupled with nitrogen depletion almost tripled the lipid productivities in two algae

Nitrogen starvation has been an effective method to enhance the lipid content in microalgae, but low biomass means the method is far from large-scale application. In this study a combination of phytohormones, indolebutyric acid (IBA) and naphthylacetic acid (NAA), was used to verify whether phytohormones can assist two microalgae, Scenedesmus SDEC-8 and Chlorella sorokiniana SDEC-18, to resist nitrogen depletion, and achieve satisfactory biomass and lipid productivity. The two algae grew poorly but accumulated high lipid concentrations under nitrogen-depleted condition without phytohormones. However, phytohormone addition maintained the biomass concentration, and furthermore yielded lipid productivities (SDEC-8: 26.7mg/L/d, SDEC-18: 25.9mg/L/d) almost 3 times as high as those in BG11. The oxidative damage caused by nitrogen depletion could be alleviated by phytohormones. The investigation demonstrated that phytohormone supplementation simultaneously improved lipid accumulation and maintained growth of microalgae, while also optimizing the biodiesel properties compared with the tactic of nitrogen depletion alone.

Adjusting irradiance to enhance growth and lipid production of Chlorella vulgaris cultivated with monosodium glutamate wastewater.

Light is one of the most important factors affecting microalgae growth and biochemical composition. The influence of illumination on Chlorella vulgaris cultivated with diluted monosodium glutamate wastewater (MSGW) was investigated. Six progressive illumination intensities (0, 30, 90, 150, 200 and 300μmol·m(-2)s(-1)), were used for C. vulgaris cultivation at 25°C. Under 150μmol·m(-2)s(-1), the corresponding specific light intensity of 750×10(-6)μmol·m(-2)s(-1) per cell, algae obtained the maximum biomass concentration (1.46g·L(-1)) on the 7th day, which was 3.5 times of that under 0μmol·m(-2)s(-1), and the greatest average specific growth rate (0.79 d(-1)) in the first 7days. The results showed the importance role of light in mixotrophic growth of C. vulgaris. High light intensities of 200 and 300μmol·m(-2)s(-1) would inhibit microalgae growth to a certain degree. The algal lipid content was the greatest (30.5%) at 150μmol·m(-2)s(-1) light intensity, which was 2.42 times as high as that cultured in dark. The protein content of C. vulgaris decreased at high light intensities of 200 and 300μmol·m(-2)s(-1). The effect of irradiance on carbohydrate content was inversely correlated with that on protein. The available light at an appropriate intensity, not higher than 200μmol·m(-2)s(-1), was feasible for economical cultivation of C. vulgaris in MSGW.

Features of Golenkinia sp. and microbial fuel cells used for the treatment of anaerobically digested effluent from kitchen waste at different dilutions

The aim of this work was to study Golenkinia sp. and microbial fuel cells (MFCs) for the treatment of anaerobically digested effluent from kitchen waste (ADE-KW) with different dilution factors. A dual-chamber MFC was fabricated for treating ADE-KW in the two chambers of the MFC and harvesting Golenkinia sp. All the anodic TN was removed more than 80%. COD removal efficiency increased from 48.2% to 76% when the dilution factor increased from 1 to 4. Maximum COD and TN removal rates were 3.56 and 3.71mg·L-1·h-1 when ADE-KW was treated without dilution in the anodic chamber. All the cathodic TN and TP removal efficiencies were approximately 90%. The highest open circuit voltage (OCV) and power density were approximately 400mV and 400mW when ADE-KW was treated directly (undiluted) in the MFC, with the highest biomass and total lipid content production of Golenkinia sp. in the cathodic chamber.

Using a tubular photosynthetic microbial fuel cell to treat anaerobically digested effluent from kitchen waste: Mechanisms of organics and ammonium removal

Anaerobically digested effluent from kitchen waste (ADE-KW) was used herein as the substrate of a tubular photosynthetic microbial fuel cell (PMFC) for power production, and also, after being diluted, as a medium for cultivation of algae in the cathodic chamber. Adding 3 mg/L phosphorus to the catholyte could efficiently enhance the algal growth and the PMFC performance. About 0.94 g/L algal biomass and 0.57 kWh/m3-ADE-KW bioelectricity were obtained from the PMFC. Soluble microbial byproduct-like material and aromatic proteins were the dominant organics in the ADE-KW, which were readily degradable in the system. About 79% of the 1550 mg/L ammonium in the anolyte transferred to the catholyte through the cation exchange membrane. The ammonium was removed mainly as electron acceptors at the cathode after being oxidized by oxygen, whereas algal assimilation only account for about 14.6% of the overall nitrogen.

Coupled microalgal cultivation with the treatment of domestic sewage and high-level CO2

ABSTRACT The ability of Scenedesmus quadricauda SDEC-13 to accumulate biomass and remove nutrients in domestic sewage from campus when incorporated with 15% CO2 was explored. The maximum specific growth rate, biomass productivity, biomass concentration, and CO2 fixation rate were 0.14 d−1, 0.08 g/L/d, 0.69 g/L, and 0.076 g-CO2/L/d, respectively. The lipid content of SDEC-13 at different culture phases was also evaluated and it increased following nutrient limitation. The removal efficiencies of total nitrogen, total phosphorus, nitrate, and ammonium were all above 90%. A coupled system was designed with hydraulic retention time of 8.33 d and biomass harvest ratio of 12%, which could yield 0.54 g/L biomass and 25% lipid content with efficient domestic sewage treatment.

The effects of algal extracellular substances on algal growth, metabolism and long-term medium recycle, and inhibition alleviation through ultrasonication

The algal extracellular substances (AESs), mainly excreted in the lag and stationary phases, inhibited the algal growth and culture recycle. The AESs consisted of protein-like substances and saccharides, which restrained the algal lipid and protein biosynthesis. Moreover, the increasing reactive oxygen species and anti-oxidative enzymes caused by AESs led to the oxidative damage and suppressed the cell activity. The AESs affected the cells through two possible ways: one is the AESs adhered to the cell surfaces; another is the cells yielded signal molecules in response to the AESs. Fortunately, the ultrasound degraded the AESs into small molecules, which clearly alleviated the limitation and recovered the algal biomass and metabolism. This study demonstrated that ultrasonication is a promising way to alleviate the AESs, which facilitating the medium recycle for long-term continuous microalgae production.