Glucose as a mitigator of cadmium-induced toxicity in chlorella sp.: Insights from cell division and photosynthesis

Glucose increased Chlorella biomass by counteracting Cd inhibition. • Cd 2+ disrupts cell wall degradation and photosynthetic systems. • Glucose co-treatment restored the cell wall degradation and chlorophyll homeostasis. Cadmium (Cd) pollution is a growing environmental challenge worldwide, impairing cellular integrity and transcriptional regulation across species and undermining ecosystem stability. This study investigates the effects of Cd 2 + stress on Chlorella pyrenoidosa in terms of growth, cell division, and photosynthetic function, and evaluates the alleviating role of soluble organic carbon supplementation, using glucose as a representative source. Results indicate that Cd 2+ exposure markedly suppresses algal growth, disrupts photosynthetic systems, reduces chlorophyll content, diminishes key photosynthetic metrics, and interferes with cell wall degradation. Biomass and specific growth rate declined from 0.6 g L −1 and 0.49 d −1 in controls to 0.38 g L −1 and 0.42 d −1 under Cd 2+ stress, but recovered to 0.95 g L −1 and 0.61 d −1 with glucose addition. Glucose supplementation substantially counteracted these inhibitory effects, partially reviving photosynthetic activity through enhanced QA-to-QB electron transfer and stabilization of porphyrin metabolism. Transcriptomic profiling revealed that Cd 2+ downregulated genes involved in cellulose degradation while upregulating those associated with lignin biosynthesis; glucose treatment restored the expression of lignin-related genes to near-control levels. Collectively, our findings demonstrate that glucose alleviates Cd 2+ toxicity in C. pyrenoidosa by restoring photosynthetic competence and cell division capacity, thereby elucidating key metabolic pathways underlying heavy-metal detoxification. Download: Download high-res image (150KB) Download: Download full-size image