<p>Straw burning is the main reason for the rise of PM₁₀ and PM_2.5 in Northeast China, especially in Jilin Province. In order to reduce the proportion of straw burning and realize carbon neutralization. A novel strain, <i>Bacillus megaterium</i> XLL1, was isolated from degraded straw and identified. This strain demonstrated the ability to degrade straw and produce humic acid. A comprehensive pathway was designed to convert straw into cattle feed, which was then transformed into biomass resources via beef cattle farming. Additionally, cow dung was processed through earthworm degradation, and <i>Chlorella</i> was employed for wastewater treatment. The recovery of <i>Chlorella</i> was achieved using a bioflocculant produced by <i>Bacillus megaterium</i> XLL1. <i>Bacillus megaterium</i> XLL1 achieved the highest floc yield of 94 mg/mL in a straw-based carbon medium. The bioflocculant derived from this strain recovered <i>Chlorella</i> with 95% efficiency. A specialized beef cattle feed formula was developed using three types of biomass resources. Based on a model of 1000 cattle, the proposed system reduced carbon emissions by 7149.5 tons of CO₂ annually. This research presents an integrated microbial-based strategy to convert straw and associated wastes into valuable biomass, significantly mitigating environmental pollution and supporting carbon neutrality goals.</p> Graphical Abstract <p></p>