Carbazole degradation in the soil microcosm by tropical bacterial strains

In a previous study, three bacterial strains isolated from tropical hydrocarbon-contaminated soils and phylogenetically identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4 and Microbacterium esteraromaticum strain SL6 displayed angular dioxygenation and mineralization of carbazole in batch cultures. In this study, the ability of these isolates to survive and enhance carbazole degradation in soil were tested in field-moist microcosms. Strain SL4 had the highest survival rate (1.8 x 107 cfu/g) after 30 days of incubation in sterilized soil, while there was a decrease in population density in native (unsterilized) soil when compared with the initial population. Gas chromatographic analysis after 30 days of incubation showed that in sterilized soil amended with carbazole (100 mg/kg), 66.96, 82.15 and 68.54% were degraded by strains SL1, SL4 and SL6, respectively, with rates of degradation of 0.093, 0.114 and 0.095 mg kg−1 h−1. The combination of the three isolates as inoculum in sterilized soil degraded 87.13% carbazole at a rate of 0.121 mg kg−1 h−1. In native soil amended with carbazole (100 mg/kg), 91.64, 87.29 and 89.13% were degraded by strains SL1, SL4 and SL6 after 30 days of incubation, with rates of degradation of 0.127, 0.121 and 0.124 mg kg−1 h−1, respectively. This study successfully established the survivability (> 106 cfu/g detected after 30 days) and carbazole-degrading ability of these bacterial strains in soil, and highlights the potential of these isolates as seed for the bioremediation of carbazole-impacted environments.

Synthesis, antibacterial and anticancer studies for new thienopyrazolopyridine and azafluorene derivatives

Reaction of thiocyanoacetamide with 3,4,5-trimethoxybenzaldehyde gave the corresponding 2-cyano-3-[3, 4,5-trimethoxyphenyl]- thioacrylamide 1. Reaction of I with ethyl acetoacetate gave the pyridine derivative 2. Cyclization of 2 with hydrazine hydrate gave the pyrazolopyridine derivative 3. Diazotization of 3 gave the diazenyl derivative 4. The latter compound 4 was reacted with malononitrile. acetylacetone and ethyl acetoacetate to give pentoazafluorene derivatives 5-7, respectively. Moreover, the cyclocondensation of compound 2 with ethylchloroacetate, bromoacetophenone, chloroacetamide and chloroacetonitrile gave the thienopyridine jerivatives 8, 11, 12 and 15. Reaction of 12 with formic acid and acetic anhydride gave the thiatriazafluorene derivatives 13 and 14, respectively. Some of the new compounds showed antimicrobial and antifungal activities. Compound 11 has good anticancer activity for liver, breast and colon cancers