Growth kinetics of RS1 on fluorene and dibenzothiophene, concomitant degradation kinetics and uptake mechanism.

Unlabelled: The current study illustrates the growth kinetics of an efficient PAH and heterocyclic PAH degrading bacterial strain, RS1 on fluorene (FLU) and dibenzothiophene (DBT) over the concentration 25-500 mg L and their concomitant degradation kinetics. The specific growth rate () was found to lie within the range of 0.32-0.57 day for FLU and 0.24-0.45 day for DBT. The specific substrate utilization rate () of FLU and DBT over the log growth phase was between 0.01 and 0.14 mg FLU mg VSS day for FLU and between 0.01 and 0.18 mg DBT mg VSS day for DBT, respectively. The and values varied within a narrow range for both FLU and DBT and they did not follow any specific trend. Dissolution together with direct interfacial uptake was the possible uptake mechanism for both FLU and DBT. The values over the log growth phase depicts the specific substrate transformation rates. Kirby-Bauer disc diffusion studies performed using an strain indicated accumulation of some toxic intermediates of FLU and DBT during their degradation. Decrease in TOC and toxicity towards the end of the degradation experiments indicates further utilization of the intermediates.

Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-021-02742-7.