Sanitary landfilling remains a cost-effective waste management strategy, employing engineered liners and leachate collection systems to mitigate environmental pollution. However, long-term degradation of compacted clay baseliners (CCLs) poses risks to environmental safety and groundwater quality. This study investigated seasonal and habitat-specific microbial communities within CCLs and leachate from the Pulau Burung Sanitary Landfill, Pinang, Malaysia, utilizing 16S rRNA gene amplicon sequencing and functional prediction via PICRUSt2. Triplicate samples were collected from leachate and baseliner layers (0–30 cm depth) during both rainy and dry seasons, alongside assessments of physicochemical properties and permeability. Significant seasonal differences (p 0.05). Microbial community shifts were primarily driven by seasonal variations in environmental parameters. Core phyla shared across both habitats included Pseudomonadota (31.15–45.88%), Bacillota (8.58–31.15%), Actinobacteriota (6.22–19.58%), Acidobacteriota (0.16–15.85%), Chloroflexota (0.85–13.84%), and Bacteroidota (1.38–12.74%). Additional phyla such as Patescibacteria (0.77–2.06%), Cyanobacteria (0.12–6.16%), Desulfobacterota (0.77–5.38%), and Verrucomicrobiota (0.59–2.33%) showed matrix-specific enrichment. Functional prediction revealed distinct enzyme profiles and metabolic pathway enrichment. Anaerobic genera such as Geobacter, Desulfuromonas, Desulfuromusa, Pseudopelobacter, Desulfotomaculum, Clostridium, Desulfitobacterium, Telmatospirillum, and Dethiobacter were associated with redox cycling and mineral-transforming processes, suggesting potential contributions to increased clay porosity and reduced structural integrity. These findings demonstrate the ecological and functional complexity of landfill microbiomes and their potential role in compromising barrier performance. The study recommends routine monitoring of microbial functional genes and the development of biogeochemically resilient clay blends or in situ biobarriers to enhance long-term containment efficacy.
Akuaka et al. (Sat,) studied this question.