Comparative assessment of minerals, heavy metal content and microbiological quality of microalgae cultivated with broiler house exhaust air

Microalgae present a sustainable solution for food and feed production due to their rich nutrient content while mitigating environmental impacts from conventional agriculture. However, their use in animal nutrition requires compliance with safety and nutritional standards. This study evaluated trace metals, heavy metals, and microbiological quality in three microalgae species (Ankistrodesmus sp., Scenedesmus sp., and Synechococcaceae) cultivated in three media (BBM, nitrogen-free BBM, and DI-water) using broiler house exhaust air. The algal biomass were analyzed for mineral and heavy metal by atomic absorption spectrophotometry, and for microbiological load including total mesophilic aerobic bacteria, total Coliform sp. and mold and yeast (cfu/g). Results showed Ankistrodesmus sp. accumulated the highest mineral and heavy metal levels (except Mg), particularly in BBM-N medium: P (2017.0 mg/kg), Ca (327 mg/kg), K (4901.1 mg/kg), Mn (17.0 mg/kg), Zn (84.7 mg/kg), and Cd (0.0121 mg/kg). Heavy metal content was highest in BBM-N cultures across species. Microbiological counts were within acceptable limits for all samples. Findings suggest that microalgae grown using broiler exhaust air can serve as a safe, mineral-rich feed ingredient, potentially lowering production costs while aiding pollution reduction. The results indicate that microalgae produced to reduce air pollutants in broiler houses can be used as animal feed and may help reduce biomass and protein production costs.

Graphical abstract