Differentiation of Bacterial, Fungal, and Algal Communities on Coastal Concrete Versus Drainage Pipes and the Coexistence of Corrosion and Healing Potentials

Abstract

Coastal concrete structures and drainage pipes are prone to microbially influenced deterioration. However, differences in microbial communities and their corrosion/healing potentials between these habitats remain unclear. Here, we compared bacterial(16S), fungal (ITS) and algal(18S) communities on coastal concrete(C) and drainage pipe(P) surfaces. Fungal and algal -diversity were significantly higher in P than in C, while bacterial diversity did not differ. {beta}-Diversity strongly separated bacterial and algal communities between habitats, but not fungi. A shared core "seed bank" of 575 bacterial, 520 fungal and 40 algal ASVs was identified. Students t-test revealed that P enriched oligotrophic degraders (Sphingomonas) and acid-producing fungi (Arxiella, Bisifusarium), whereas C selected for halotolerant EPS-producing bacteria (Tunicatimonas, Muricauda) and the extremotolerant alga Coelastrella. db-RDA linked these differences to salinity, NH4+-N, NO3--N, and COD. Functional prediction indicated a shift from metabolism pathways in C to signaling in P. Co-occurrence networks revealed cross-kingdom competition and within-kingdom cooperation, especially among algae. Importantly, both habitats harbored microorganisms with documented corrosion and healing potentials, but under natural conditions, net deterioration dominated, microbial healing is hardly to counteract the negative effects. This study provides a functional taxonomic framework for understanding and managing concrete microbiomes in coastal and sewer infrastructure. ImportanceConcrete is the most widely used construction material, and its deterioration in coastal and sewer environments poses significant economic and safety challenges. Microorganisms play a dual role in concrete durability -- they can both corrode and heal concrete, but the net outcome under natural conditions is poorly understood. Most studies have focused on bacteria alone, overlooking the contributions of fungi and algae, and few reports on the of coastal concrete which also exist the microbially influenced concrete corrosion (MICC) similar to sewer. Here, we simultaneously analyzed all three microbial kingdoms on coastal concrete and drainage pipes. We found that while concrete surfaces harbor a diverse "seed bank" of microorganisms potentially involved in both corrosion and healing, under natural conditions, net deterioration dominated, indicating microbial healing is hard to counteract the negative effects from the environment and microbial. Our work provides a functional framework to guide the development of microbiome-based strategies for enhancing concrete durability, such as activating rare healing taxa in drainage pipes or selecting for endogenous healers in marine environments.