Optimal bioaugmentation fosters a highly integrated and efficient microbial network for rapid trichloroethene dechlorination

Bioaugmentation is a leading strategy for remediating groundwater contaminated with chlorinated ethenes. However, the optimized dosage to enhance synergetic interactions between consortia and electron donors remains poorly defined. This study investigated the effects of co-injecting a dechlorinating consortium (acclimated JL-1(KCTC11782BP)) at varying concentrations (0–10 % v/v) with lactate (0–1000 mM) on trichloroethene (TCE) degradation in microcosm systems over 40 days. Complete dechlorination of ethene occurred within 20 days across all treatments except 1000 mM lactate, which suppressed activity. The fastest and most robust response arose at 5.3 % acclimated JL-1 with 530 mM lactate, yielding ethene within 5 days. Quantitative PCR showed ∼10-fold enrichment of Dehalococcoides mccartyi tceA during complete TCE removal, and tceA abundance correlated positively with ethene production (p < 0.05). The presence of fermenting bacteria, including Pelosinus, Acetobacterium , and Sporomusa , was crucial for providing essential electron donors and nutrients to support the activity of organohalide-respiring bacteria, particularly Dehalococcoides . With a 5.3 % acclimated JL-1 and 530 mM lactate co-injection, dechlorination facilitated the development of a highly integrated microbial network, characterized by a low network diameter (2), a high average clustering coefficient (0.99), and a short average path length (1.045), all indicative of highly efficient and coordinated microbial interactions. These data delineate quantitative operating ranges for consortium and donor addition, identify an inhibitory upper bound for lactate, and mechanistically link community topology to dechlorination rates. This study can provide tunable, data-driven parameters for field bioaugmentation design, including initial JL-1 loading, lactate setpoints, and monitoring biomarkers. • Optimized bioaugmentation achieves complete TCE to ethene dechlorination in 5 days • Co-dosing of 5.3 % JL-1 consortium and 530 mM lactate accelerated TCE dechlorination • Network analysis links community topology to stable dechlorination efficiency • Syntrophic fermenters ( Pelosinus, Sporomusa ) are vital for Dehalococcoides • Optimal conditions create a compact and highly efficient microbial interactions