A process for simultaneously achieving phenol biodegradation and polyhydroxybutyrate accumulation using Cupriavidus taiwanesis 187

Estrone degrading enzymes of Spirulina CPCC-695 and synthesis of bioplastic precursor as a by-product

Estrone, a steroidal estrogen that is persistently contaminating the surface water has been classified as an endocrine disruptor and as Group-1 carcinogen by the World Health Organization. Long-term exposure to estrone-contaminated water disrupt physiology, behaviour and sexual development of living organisms that lead to many disorders. So, it has to be eliminated from our surrounding. Its biological degradation is a cost effective and eco-friendly approach. The present study targets to predict the degradation pathway and understand the role of cyanobacterial enzymes: oxidoreductases (laccase, peroxidase) and esterase in estrone degradation. Poly-β-hydroxy butyrate (PHB) was also quantified as a by-product of estrone biodegradation. The estrone degradation pathway was predicted using EAWAG-BBD/PPS database. Spirulina CPCC-695 was grown in different concentration of estrone (20 mg/l, 50 mg/l, 100 mg/l and 200 mg/l). The culture without estrone was considered as control. The culture supernatant was used for testing laccase and esterase activity whereas the biomass was used to test peroxidase activity and quantify by-product (PHB). The enzymes showed concentration-dependent activities. Maximum enzyme activities were seen at 20 mg/l estrone. Spirulina CPCC-695 utilizes estrone as a carbon source and degrades it to produce pyruvate which forms acetyl CoA that undergo condensation, reduction and polymerization to form PHB. Maximum PHB (169 μg) was also produced at 20 mg/l as a by-product during degradation.

High-efficiency biodegradation of chloramphenicol by enriched bacterial consortia: Kinetics study and bacterial community characterization

The risk of environmental pollution caused by chloramphenicol has necessitated special attention. Biodegradation has tremendous potential for chloramphenicol removal in the environment. Six chloramphenicol-degrading consortia were acclimated under different culture conditions to investigate their chloramphenicol biodegradation behaviors, and the bacterial community structures were comprehensively characterized. The enriched consortia CL and CH which utilized chloramphenicol as their sole carbon and energy source could thoroughly degrade 120 mg/L chloramphenicol within 5 days, and the mineralization rate reached up to 90%. Chloramphenicol biodegradation kinetics by different enriched consortia fit the modified Gompertz model or the first-order decay model (R²≥0.97). Consortia CL could almost completely degrade 1-500 mg/L CAP with a final mineralization rate of 87.8-91.7%. Chloramphenicol 3-acetate was identified to be a major intermediate of CAP biodegradation by metabolite analysis and enzyme activity assay. 16S rRNA sequencing analysis revealed that the diversities and abundances of the main genera in the enriched consortia were distinct from each other. Forty-one core OTUs belonging to 18 genera were the core bacteria which might be related to chloramphenicol biodegradation. Among them, the genera Sphingomonas, Chryseobacterium, Cupriavidus, Bradyrhizobium, Burkholderia, and Afipia with high abundance may play potential roles for chloramphenicol biodegradation.