Possible Processes and Mechanisms of Hexachlorobenzene Decomposition by the Selected Comamonas testosteroni Bacterial Strains

Abstract

Background: The bacterial destructing activity toward pesticides has been the focus of research in the last few decades. Hexachlorobenzene is included in the organochlorine pesticides group that are prohibited for use. However, large hexachlorobenzene amounts are still concentrated in the soil, stressing the relevance of research on hexachlorobenzene-destroying bacteria. Methods: The ability to destroy hexachlorobenzene by Comamonas testosteroni UCM B-400, B-401, B-213 strains was investigated and established. Bacteria were cultivated (7 days at 28 °C) in mineral Luria-Bertrani (LB) medium with three hexachlorobenzene doses: 10, 20, 50 mg/L. The hexachlorobenzene concentrations were recorded by a gas chromatography method. Results: The results showed that C. testosteroni UCM B-400, B-401 have high destructive activity toward hexachlorobenzene. The highest (50 mg/L) initial concentration decreased to 41.5 and 43.8%, respectively, for C. testosteroni UCM B-400, B-401. The unadapted C. testosteroni UCM B-213 was tolerant to hexachlorobenzene (cell titers after cultivating with 10.0, 20.0, 50.0 mg/mL were higher compared to initial titer), but had a low-destructing activity level (two times less than B-400 and B-401). Conclusions: Bacterial strains C. testosteroni UCM B-400, B-401 can be seen as a potential soil bioremediation from hexachlorobenzene pollution.

Study on the degradation and metabolic mechanism of four quinolone antibiotics by mixed strains

“…Although there is no literature confirming the biodegradability of QNs in Leucobacter sp. currently, Actinobacteria, such as Corynebacterium and Leukobacterium, are often the main carriers of sulfonamide resistance (SR) genes (sul1 and intI1) (Lin et al, 2017;Xia et al, 2019).In previous studies, Comamonas testosteroni has been confirmed to be able to degrade organic substances such as hexachlorobenzene (Dimova et al, 2022), phenanthrene, naphthalene (Goyal and Zylstra, 1997), and 4-chlorophenol (Bae et al, 1997;Wang et al, 2020). What's more, it can be found in Figure 3 that carbon sources have little effect on the community composition of the QNs degrading and tolerant bacteria, the difference between groups is mainly controlled by the type of antibiotics.…”

Soil activity and microbial community response to nanometal oxides were not due exclusively to a particle size effect

“…LB medium had been used to isolate microorganisms from soil to investigate their biotechnological potential 56–58 or to understand the toxicity of chemical agents, such as ENMs. 59–62 Future studies, however, need to consider aqueous solutions more environmentally relevant with closer characteristics to the matrix in the study.…”

“…Overall, our contrasting results compared to other reports highlight the importance of evaluating the dissolution of the specific compounds in the study as they can differ between manufacturers or product lot. 55 LB medium had been used to isolate microorganisms from soil to investigate their biotechnological potential [56][57][58] or to understand the toxicity of chemical agents, such as ENMs. [59][60][61][62] Future studies, however, need to consider aqueous solutions more environmentally relevant with closer characteristics to the matrix in the study.…”

Microbial Bioremediation of Environmental Pollution

“…The aim of Dimova et al's [20] study was to determine the possible ability of Comamonas testosteroni bacterial strains to degrade hexachlorobenzene (included in the organochloride pesticide group that is banned for use). The ability of the C. testosteroni UCM B-400, B-401 and B-213 strains to decompose hexachlorobenzene was investigated for the first time in the literature, and their destructive activity was confirmed biochemically.…”

“…Moreover, the microbial consortium (no. 3)-a mixture of all six mentioned strains-exhibited strong degradation activity for all the pesticides and consequently appeared to be a potential inoculum candidate [20].…”