Cultivation of Scenedesmus dimorphus with air contaminants from a pig confinement building

Nutritional and Amino Acid Composition of Scenedesmus sp. Cultivated Under Various Light Intensities

Microalgae like Scenedesmus sp. are promising alternatives for sustainable food and animal feed due to their high protein content and adaptability to different light intensities. Optimal light enhances growth and nutrient accumulation, while excessive light can reduce productivity. This study investigates the effects of different light intensities (100-300 µmol m⁻2 s⁻1) on the growth performance and nutritional composition of Scenedesmus sp., aiming to improve microalgae production efficiency and contribute to commercial standards for sustainable protein sources. Results show that dry biomass concentration (0.975 g L-1) and cell count (2.96) peaked at a light intensity of 200 μmol m-2 s-1 (P < 0.0001), while dry biomass decreased at 300 μmol m⁻2 s⁻1. Scenedesmus sp. grown at 200 and 300 µmol m-2 s-1 had higher carbohydrate contents (50.1% and 54%, P < 0.001), while the highest lipid content (42.3%) was observed at 100 µmol m-2 s-1. The highest crude protein was recorded at 200 µmol m-2 s-1 (15.6%, P < 0.0001). Regarding amino acid composition, leucine was the most abundant essential amino acid (1.20 mg/100 mg dry weight), while glutamic acid was the most abundant non-essential amino acid (1.73 mg/100 mg). For color characteristics, biomass produced at 300 µmol m-2 s-1 exhibited a darker color, with the lowest L* value (21.66), and a more yellowish hue compared to 200 µmol m-2 s-1. These findings highlight the importance of optimizing light conditions to enhance Scenedesmus sp. productivity for sustainable animal feed applications. This study indicates that the productivity of Scenedesmus sp. could be enhanced for biomass and protein production by maintaining an optimal light regime. By maximizing biomass yield and nutrient composition, this study supports the development of microalgae-based protein sources that can serve as a viable alternative to conventional feed ingredients, contributing to more sustainable and efficient feed production systems.

Predicting Tuberculosis Risk in Cattle, Buffaloes, Sheep, and Goats in China Based on Air Pollutants and Meteorological Factors

Tuberculosis is a zoonotic chronic respiratory infectious disease caused by the Mycobacterium tuberculosis complex. The outbreak and epidemic of tuberculosis can seriously threaten human and veterinary health. To investigate the effects of environmental factors on tuberculosis in domestic ruminants, we collected data regarding the prevalence of tuberculosis in cattle, buffaloes, sheep, and goats in China (1956-2024) from publicly published literature and available databases. We identified the key risk factors among six major air pollutants and 19 bioclimatic variables; simulated the risk distribution of tuberculosis in cattle, buffaloes, sheep, and goats in China using the maximum entropy ecological niche model; and evaluated the effects of environmental factors. The area under the curve of the model was 0.873 (95% confidence interval, 0.851-0.895). The risk factors that most significantly influenced the prevalence of tuberculosis were the nitrogen dioxide (NO2) level, mean temperature of the coldest quarter, cattle distribution density, sheep distribution density, ozone (O3) level, and precipitation of the driest month. The predicted map of tuberculosis risk in cattle, buffaloes, sheep, and goats indicated that the high-risk regions were mainly distributed in South, North, East, and Northwest China. Improved surveillance is needed in these high-risk areas, and early preventive measures must be implemented based on the risk factors identified to reduce the future prevalence of tuberculosis in cattle, buffaloes, sheep, and goats.

Photobioreactor systems for mitigating ammonia and carbon dioxide from a broiler house

This study investigated the effectiveness of photobioreactor (PBR) systems in reducing air pollutants emitted from broiler houses. It focused on two microalgae species and one cyanobacteria grown under different media conditions and investigated their ability to mitigate ammonia (NH3) and carbon dioxide (CO2) in the exhaust air of a broiler house. Ankistrodesmus sp. achieved the highest cell concentrations across all experiments, with maximum dry biomass concentration observed under Nitrogen-free Bold's Basal Medium (BBM-N) culture condition. Scenedesmus sp. showed the highest NH3 mitigation efficiency (52.3%) with BBM-N culture, while Synechococcaceae species exhibited the highest CO2 mitigation efficiency (70.8%) with DI-water culture condition. Operating costs for producing 1.0 g L-1day-1 of dry microalgal biomass ranged from 0.10 to 0.35 USD L-1day-1. The cost of removing 1 g of NH3 ranged from $3.53-7.16, while for CO2, it ranged from $0.04-0.59. The study also evaluated the economic feasibility of this approach, demonstrating significant cost savings in biomass and protein production. These findings highlight the potential of PBR systems as a sustainable solution for reducing air pollutants in broiler house environments.

Microalgae cultivation using ammonia and carbon dioxide concentrations typical of pig barns

While global population growth drives increased production efficiency in animal agriculture, there is a growing demand for environmentally friendly practices, particularly in reducing air pollutant emissions from concentrated animal feeding operations. This study explores the potential of cultivating microalgae in photobioreactors (PBRs) as an eco-friendly and cost-effective approach to mitigate NH3 and CO2 emissions from pig barns. Unlike traditional physicochemical mitigation systems, microalgae offer a renewable solution by converting pollutants into valuable biomass. The research focused on Scenedesmus dimorphus growth under typical NH3 and CO2 concentrations found in the indoor air of pig barns. Four NH3 (0, 12, 25, and 50 ppm) and four CO2 concentrations (350, 1200, 2350, and 3500 ppm) were tested using photobioreactors. Results showed a maximum specific growth rate of 0.83 d-1 with 12 ppm NH3 and 3500 ppm CO2. The dry biomass concentration was significantly higher (1.16 ± 0.08 g L-1; p < 0.01) at 25 ppm NH3 and 2350 ppm CO2 than other test conditions. S. dimorphus demonstrated the peak NH3 and CO2 fixation rates (23.8 ± 2.26 mg NH3 L-1 d-1 and 432.24 ± 41.09 mg CO2 L-1 d-1) at 25 ppm NH3 and 2350 ppm CO2. These findings support the feasibility of using algae to effectively remove air pollutants in pig barns, thereby improving indoor air quality.

Pollutant Gases to Algal Animal Feed: Impacts of Poultry House Exhaust Air on Amino Acid Profile of Algae

Algae provide a rich source of proteins, lipids, vitamins, and minerals, making them valuable feed ingredients in animal nutrition. Beyond their nutritional benefits, algae have been recognized for their potential to mitigate the negative environmental impacts of poultry production. Poultry production is crucial for the global food supply but contributes to environmental concerns, particularly in terms of ammonia and carbon dioxide gas emissions. This study emphasizes the importance of reducing greenhouse gas and ammonia production in poultry operations by utilizing algae species suitable for animal consumption, highlighting the need for sustainable feed sources. This study investigated the effects of poultry exhaust air and culture conditions on the amino acid profiles of three microalgae species, namely, Scenedesmus sp. (AQUAMEB-60), Ankistrodesmus sp. (AQUAMEB-33), and Synechococcaceae (AQUAMEB 32). The experiments were conducted in a commercial broiler farm in Bursa, Turkey, focusing on reducing pollutant gas emissions and utilizing poultry exhaust air in algae cultivation. The highest protein content of 50.4% was observed in the biomass of Synechococcaceae with BBM and DI water. Scenedesmus sp. had the highest carbohydrate content of 33.4% cultivated with DI water. The algae biomass produced from Synechococcaceae growth with DI water was found to have the highest content of essential and nonessential amino acids, except for glutamic acid and glycine. The arsenic, cadmium, and mercury content showed variations within the following respective ranges: 1.076-3.500 mg/kg, 0.0127-0.1210 mg/kg, and 0.1330-0.0124 mg/kg. The overall operating costs for producing 1.0 g L-1 d-1 of dry algal biomass with the existing PBR system were $0.12-0.35 L-1 d-1, $0.10-0.26 L-1 d-1, and $0.11-0.24 L-1 d-1 for Scenedesmus sp., Ankistrodesmus sp., and Synechococcaceae, respectively. The operating cost of producing 1.0 g L-1 d-1 of protein was in the range of $0.25-0.88 L-1 d-1 for the three algae species. The results provide insights into the potential of algae as a sustainable feed ingredient in animal diets, emphasizing both environmental and economic considerations. The results demonstrated a considerable reduction in the production costs of dry biomass and protein when utilizing poultry house exhaust air, highlighting the economic viability and nutritional benefits of this cultivation method.

Nutritional Value of Microalgae and Cyanobacteria Produced with Batch and Continuous Cultivation: Potential Use as Feed Material in Poultry Nutrition

Recently, the demand for new alternative feedstuffs that do not contain chemical residue and are not genetically modified has been increased for sustainability in poultry production. In this respect, the usage of algae as animal feed is very promising as an alternative feed ingredient that reduces pollutant gases from animal production facilities. The aim of the current study is to investigate the usage possibility of algae, through determining nutritional value and production cost, as a feed ingredient in poultry nutrition. Three microalgae species, including Scenedesmus sp., Ankistrodesmus sp., and Synechococcaceae, were produced with batch and continuous cultivation to determine the difference in the lipid, protein, carbohydrate, fatty acid, and amino acid profiles, as well as the color characteristics and production cost. The highest lipid content of 72.5% was observed in algae biomass produced from Synechococcaceae with batch cultivation, whereas the highest protein level was found in algae biomass produced by Synechococcaceae under continuous cultivation practice (25.6%). The highest content of PUFA was observed in Scenedesmus sp. harvested from both batch and continuous cultivation (35.6 and 36.2%), whereas the lowest content of PUFA was found in Synechococcaceae harvested with continuous cultivation (0.4%). Continuously cultivated of Scenedesmus sp. had higher carbohydrate content than batch-cultivated Scenedesmus sp. (57.2% vs. 50.1%). The algae biomass produced from Synechococcaceae was found to have a higher content of essential amino acids, except lysine and histidine, compared to Scenedesmus sp. and Ankistrodesmus sp. Cultivation practices also affected the amino acid level in each algae species. The continuous cultivation practice resulted in a higher level of essential amino acids, except glycine. Synechococcaceae had richer essential amino acid content except for proline and ornithine, whereas continuous cultivation caused an incremental increase in non-essential amino acids. The lightness value was found to be the lowest (13.9) in Scenedesmus sp. that was continuously cultivated. The current study indicated that Scenedesmus sp. could be offered for its high PUFA and lysine content, whereas Synechococcaceae could have potential due to its high content of methionine and threonine, among the investigated microalgae and Cyanobacteria.

Growth of Scenedesmus dimorphus in swine wastewater with versus without solid-liquid separation pretreatment

Scenedesmus dimorphus was cultivated in raw and pretreated swine wastewater (SW) with 6-L photobioreactors (PBRs) to investigate the effect of solid-liquid separation on algal growth. The same aerated PBRs containing no algae were used as control. Moderate COD and nitrogen removal from the SW was achieved with the algal PBRs. However, compared to the control reactors, they offered no consistent treatment boost. Improved algal growth occurred in the pretreated SW, as measured by maximum algal cell count (3202 ± 275 × 10⁶ versus 2286 ± 589 × 10⁶ cells L^-1) and cell size. The enhanced algal growth in the pretreated SW resulted in relatively high nitrogen (5.7 %) and organic matter contents in the solids harvested at the end of cultivation experiments, with ∼25.6 % of nitrogen in the SW retained in the solids and ∼9.1 % absorbed by algae. The pretreatment also resulted in elevated phosphorus removal. This study is anticipated to foster the development of microalgae-based SW treatment processes.