Effect of GR24 concentrations on tetracycline and nutrient removal from biogas slurry by different microalgae-based technologies

Contaminant removal performance and lipid productivity of a cyanobacteria-bacteria consortium containing exogenous phytohormones during the treatment of antibiotic-polluted wastewater

In this study, a cyanobacteria-bacteria consortium containing native wastewater bacteria and immobilized Synechococcus sp. was constructed. The cyanobacterial cellular responses (including growth, biomass and lipid productivity) and contaminant removal ability (for TN, TP, COD and antibiotics) in the consortium were evaluated during the advanced treatment of wastewater containing 10-50 μg/L of mixed antibiotics (amoxicillin, tetracycline, erythromycin, sulfadiazine and ciprofloxacin) with the addition of a certain phytohormone (indole-3-acetic acid, gibberellin A3 or 6-benzylaminopurine) at trace level within a period of four days. Each phytohormone promoted the growth of Synechococcus sp. and increased the tolerance of Synechococcus sp. to mixed antibiotics. Indole-3-acetic acid coupled to moderate antibiotic stress could elevate lipid productivity and lipid content of Synechococcus sp. to 33.50 mg/L/day and 43.75%, respectively. Phytohormones increased the pollutant removal performance of the cyanobacteria-bacteria consortium through the stimulation of cyanobacterial growth and the regulation of cyanobacteria-bacteria interaction, which increased the abundances of microalgae-associated bacteria including Flavobacterium, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Bosea, Sphingomonas and Emticicia. Up to 80.83%, 98.06%, 83.26%, 99.84%, 99.50%, 89.41%, 65.61% and 60.65% of TN, TP, COD, amoxicillin, tetracycline, erythromycin, sulfadiazine and ciprofloxacin were removed by the consortium with the addition of phytohormones. In general, indole-3-acetic acid was the optimal phytohormone for enhancing lipid production and contaminant removal performance of the cyanobacteria-bacteria consortium.

Algae-Mediated Removal of Prevalent Genotoxic Antibiotics: Molecular Perspective on Algae-Bacteria Consortia and Bioreactor-Based Strategies

Antibiotic pollution poses a potential risk of genotoxicity, as antibiotics released into the environment can induce DNA damage and mutagenesis in various organisms. This pollution, stemming from pharmaceutical manufacturing, agriculture, and improper disposal, can disrupt aquatic ecosystems and potentially impact human health through the consumption of contaminated water and food. The removal of genotoxic antibiotics using algae-mediated approaches has gained considerable attention due to its potential for mitigating the environmental and health risks associated with these compounds. The paper provides an in-depth examination of the molecular aspects concerning algae and bioreactor-driven methodologies utilized for the elimination of deleterious antibiotics. The molecular analysis encompasses diverse facets, encompassing the discernment and profiling of algae species proficient in antibiotic degradation, the explication of enzymatic degradation pathways, and the refinement of bioreactor configurations to augment removal efficacy. Emphasizing the significance of investigating algal approaches for mitigating antibiotic pollution, this paper underscores their potential as a sustainable solution, safeguarding both the environment and human health.

Effect of different concentrations of gibberellins on attenuation of nutrient and antibiotics from aquaculture wastewater using microalgae-bacteria-fungi consortia system

This study assessed the effect of gibberellins (GAs) concentrations on antibiotic and nutrient removal using diverse microalgal-bacterial-fungal consortia. Five systems (Chlorella vulgaris, T1; C. vulgaris + S395-2 + Clonostachys rosea, T2; C. vulgaris + S395-2 + Ganoderma lucidum, T3; C. vulgaris + S395-2 + Pleurotus pulmonarius, T4; and C. vulgaris + S395-2, T5) were established, and optimal conditions and effective symbiosis were applied to improve antibiotic and nutrient removal. Consortium growth was T2 > T3 > T5 > T4 > T1, while GA impact ranked 50 mg L-1 > 20 mg L-1 > 80 mg L-1 > 0 mg L-1. After 7 days at 50 mg L-1 GAs, total nitrogen (TN), NH4-N, NO3-N, and total phosphorous (TP) removal reached 85.97 %, 78.08 %, 86.59 %, and 94.39 %, respectively. Florfenicol, oxytetracycline hydrochloride, ofloxacin, and sulfamethoxazole removal efficiencies were 67.77 %, 98.29 %, 90.47 %, and 94.92 %, respectively. These findings highlight GAs' significant role in enhancing antibiotic and nutrient removal.

Growth of Scenedesmus obliquus in anaerobically digested swine wastewater from different cleaning processes for pollutants removal and biomass production

Anaerobically digested swine wastewater (ASW) purification by microalgae provides a promising strategy for nutrients recovery, biomass production and CO2 capture. However, the characteristics of ASW from different cleaning processes vary greatly. At present, the cultivation of microalgae in ASW from different manure cleaning processes is rarely investigated and compared. That may bring uncertainty for microalgae growth using different ASW in large-scale application. Thus, the ASW from three cleaning processes were tested for cultivating microalgae, including manure dry collection (I), water flushing (II) and water submerging processes (III). The characteristics of ASW from three manure cleaning processes varied greatly such as nutrient and heavy metals levels. High concentration of ammonia and copper in ASW significantly inhibited microalgae growth. Fortunately, the supply of high CO2 (10%) effectively alleviated negative influences, ensuring microalgal growth at low dilution ratio. The characteristics of three ASW resulted in significant differences in microalgae growth and biomass components. The maximal biomass production in optimal diluted ASW-I, II and III reached 1.46 g L-1, 2.19 g L-1 and 2.47 g L-1, respectively. The removal of organic compounds, ammonia and phosphorus by optimal microalgae growth in diluted ASW-I, II and III was 50.6%/94.2%/64.7%, 63.7%/82.3%/57.6% and 83.2%/91.7%/59.7%, respectively. The culture in diluted ASW-I, II and III obtained the highest lipids production of 12.1 mg L-1·d-1, 16.5 mg L-1·d-1 and 19.4 mg L-1·d-1, respectively. The analysis of lipids compositions revealed that the proportion of saturated fatty acids accounted for 36.4%, 32.4% and 27.9 % in optimal diluted ASW-I, II and III, as ideal raw materials for biodiesel production.

Phytohormone gibberellins treatment enhances multiple antibiotics removal efficiency of different bacteria-microalgae-fungi symbionts

To develop and characterize novel antibiotics removal biomaterial technology, we constructed three different bacteria-microalgae-fungi consortiums containing Chlorella vulgaris (C. vulgaris), endophytic bacterium, Clonostachys rosea (C. rosea), Ganoderma lucidum, and Pleurotus pulmonarius. The results showed that under treatment with 50 mg/L of gibberellins (GAs), the three bacteria-microalgae-fungi symbionts had maximal growth rates (0.317 ± 0.030 d-1) and the highest removal efficiency for seven different antibiotics. Among them, C. vulgaris-endophytic bacterium-C. rosea symbiont had the best performance, with antibiotics removal efficiencies of 96.0 ± 1.4 %, 91.1 ± 7.9 %, 48.7 ± 5.1 %, 34.6 ± 2.9 %, 61.0 ± 5.5 %, 63.7 ± 5.6 %, and 54.3 ± 4.9 % for tetracycline hydrochloride, oxytetracycline hydrochloride, ciprofloxacin, norfloxacin, sulfadiazine, sulfamethazine, and sulfamethoxazole, respectively. Overall, the present study demonstrates that 50 mg/L GAs enhances biomass production and antibiotics removal efficiency of bacteria-microalgae-fungi symbionts, providing a framework for future antibiotics-containing wastewater treatment using three-phase symbionts.

Enhancement of carbon nanotubes on microalgal-fungal consortium formation and wastewater treatment

As a promising material with an efficient light capture capability, a low amount of carbon nanotubes can affect growth and photosynthesis by regulating microalgal cells, thereby enhancing the pollutant removal efficiency in wastewater. In this study, microalgal-fungal consortia of Chlorella vulgaris and Ganoderma lucidum were developed with different types and concentrations of carbon nanotubes. The treatment effect of microalgal-fungal consortia on simulated digestate was also studied. The results demonstrate that 1.5 mg/L of carboxylated multi-walled carbon nanotubes remarkably promoted the formation, growth and photosynthesis of consortium. The dry weight and chlorophyll a content reached 19.3 ± 0.53 mg/symbiont and 27.3 ± 0.52 μg/L, respectively. Moreover, the removal efficiency of chemical oxygen demand, total nitrogen, total phosphorus and tetracycline hydrochloride were 94.1%, 65.5%, 61.9% and 96.2%, respectively. Overall, these findings suggest a promising future for the use of carbon nanotubes in wastewater treatment by regulating microalgal-fungal consortia.

Attenuation of antibiotics from simulated swine wastewater using different microalgae-based systems

Antibiotic misuse are potentially harmful to the environment and human health. Four algal symbionts were constructed using Chlorella vulgaris, endophytic bacterium and Clonostachys rosea (C. rosea) as the biomaterials. The growth, photosynthetic activity, and antibiotic removal efficiency of symbiont under different initial antibiotic concentrations was analyzed. The results showed that the microalgae-bacteria-fungi symbiont had a maximum growth rate of 0.307 ± 0.030 d-1 and achieved 99.35 ± 0.47%, 81.06 ± 7.83%, and 79.15 ± 7.26% removal of oxytetracycline (OTC), sulfadimethazine (SM2), and ciprofloxacin hydrochloride (CPFX), respectively, at an initial antibiotic concentration of 0.25 mg/L. C. rosea has always existed as a biocontrol fungus. In this study, it was innovatively used to construct algal symbionts and used for antibiotic wastewater treatment with a high efficiency. The results contribute to the development of appropriate bioaugmentation strategies and the design of an algal symbiont process for the treatment of antibiotic-containing wastewater.

Novel Strigolactone Mimics That Modulate Photosynthesis and Biomass Accumulation in Chlorella sorokiniana

In terrestrial plants, strigolactones act as multifunctional endo- and exo-signals. On microalgae, the strigolactones determine akin effects: induce symbiosis formation with fungi and bacteria and enhance photosynthesis efficiency and accumulation of biomass. This work aims to synthesize and identify strigolactone mimics that promote photosynthesis and biomass accumulation in microalgae with biotechnological potential. Novel strigolactone mimics easily accessible in significant amounts were prepared and fully characterized. The first two novel compounds contain 3,5-disubstituted aryloxy moieties connected to the bioactive furan-2-one ring. In the second group of compounds, a benzothiazole ring is connected directly through the cyclic nitrogen atom to the bioactive furan-2-one ring. The novel strigolactone mimics were tested on Chlorella sorokiniana NIVA-CHL 176. All tested strigolactones increased the accumulation of chlorophyll b in microalgae biomass. The SL-F3 mimic, 3-(4-methyl-5-oxo-2,5-dihydrofuran-2-yl)-3H-benzothiazol-2-one (7), proved the most efficient. This compound, applied at a concentration of 10-7 M, determined a significant biomass accumulation, higher by more than 15% compared to untreated control, and improved the quantum yield efficiency of photosystem II. SL-F2 mimic, 5-(3,5-dibromophenoxy)-3-methyl-5H-furan-2-one (4), applied at a concentration of 10-9 M, improved protein production and slightly stimulated biomass accumulation. Potential utilization of the new strigolactone mimics as microalgae biostimulants is discussed.

Wastewater from textile digital printing as a substrate for microalgal growth and valorization

This study aims at evaluating an innovative biotechnological process for the concomitant bioremediation and valorization of wastewater from textile digital printing technology based on a microalgae/bacteria consortium. Nutrient and colour removal were assessed in lab-scale batch and continuous experiments and the produced algae/bacteria biomass was characterized for pigment content and biomethane potential. Microbial community analysis provided insight of the complex community structure responsible for the bioremediation action. Specifically, a community dominated by Scenedesmus spp. and xenobiotic and dye degrading bacteria was naturally selected in continuous photobioreactors. Data confirm the ability of the microalgae/bacteria consortium to grow in textile wastewater while reducing the nutrient content and colour. Improvement strategies were eventually identified to foster biomass growth and process performances. The experimental findings pose the basis of the integration of a microalgal-based process into the textile sector in a circular economy perspective.