Reuse of treated urban wastewater on the growth and physiology of Medicago sativa L. cv. Gea and Petroselinum crispum L. cv. Commun: correlation with oxydative stress and DNA damage

New insights into the typical nitrogen-containing heterocyclic compound-quinoline degradation and detoxification by microbial consortium: Integrated pathways, meta-transcriptomic analysis and toxicological evaluation

As the primary source of COD in industrial wastewater, quinoline has aroused increasing attention because of its potential teratogenic, carcinogenic, and mutagenic effects in the environment. The activated sludge isolate quinoline-degrading microbial consortium (QDMC) efficiently metabolizes quinoline. However, the molecular underpinnings of the degradation mechanism of quinoline by QDMC have not been elucidated. High-throughput sequencing revealed that the dominant genera included Diaphorobacter, Bacteroidia, Moheibacter and Comamonas. Furthermore, a positive strong correlation was observed between the key bacterial communities (Diaphorobact and Bacteroidia) and quinoline degradation. According to metatranscriptomics, genes associated with quorum sensing, ABC transporters, component systems, carbohydrate, aromatic compound degradation, energy metabolism and amino metabolism showed high expression, thus improving adaptability of microbial community to quinoline stress. In addition, the mechanism of QDMC in adapting and resisting to extreme environmental conditions in line with the corresponding internal functional properties and promoting biogegradation efficiency was illustrated. Based on the identified products, QDMC effectively mineralized quinoline into low-toxicity metabolites through three major metabolic pathways, including hydroxyquinoline, 1,2,3,4-H-quinoline, 5,6,7,8-tetrahydroquinoline and 1-oxoquinoline pathways. Finally, toxicological, genotoxicity and phytotoxicity studies supported the detoxification of quinoline by the QDMC. This study provided a promising approach for the stable, environmental-friendly and efficient bioremediation applications for quinoline-containing wastewater.

Impact of short-term irrigation of diverse distillery wastewater types on plant attributes and antioxidative enzymes of pea (Pisum sativum L. var. Rachna)

The study was focused on evaluating the short-term irrigation effect of three different types of distillery wastewater, i.e., untreated, primary treated, and secondary treated, on the germination, growth, photosynthetic pigments, and antioxidant enzymes of pea (Pisum sativum L. var. Rachna). The findings indicated that exposure to 50% secondary treated distillery wastewater (ST50) resulted in the maximum values for positive germination parameters of pea, including germination percentage, germination value, germination index, peak value, vigor index, speed of germination, and tolerance index. The minimum values were observed at 100% concentration of untreated wastewater (UT100). In contrast, the maximum values for various negative germination parameters, i.e., percent inhibition, seedling mortality, and germination period, were observed at UT100 and minimum at ST50. All the growth parameters studied, i.e., length of shoot, length of root and length of seedlings, fresh weight of shoot, fresh weight of root, dry weight of shoot, and dry weight of root, showed maximum values at ST50 and minimum at UT100. Photosynthetic pigment analysis also followed a similar trend. The antioxidative enzyme characterization of Pisum sativum L. var. Rachna revealed the minimum values of catalase, ascorbic peroxidase, glutathione reductase, and superoxide dismutase at ST25 (25% concentration of secondary treated distillery wastewater) and maximum values were observed at UT100.