A Novel ZnONPs/PVA-Functionalized Biomaterials for Bacterial Cells Immobilization and its Strengthening Effects on Quinoline Biodegradation

Degradation of aniline: sodium alginate/modified pomelo cellulose double cross-linking system as a bacterial immobilization carrier

Pectin cellulose grafted with glycidyltrimethylammoniochloride (GTMAC) was successfully obtained following the processes of depectinfibrillation and cellulose cationization using ordinary Shatian pomelo peel produced in Yongzhou, Hunan, as the raw material. This is the first report on a new type of functionalized sodium alginate-immobilized material prepared from the fibers of pomelo peel. The material was prepared by combining modified pomelo peel cellulose and sodium alginate following the processes of physical and chemical double cross-linking. The prepared material was used to embed the target bacteria to achieve the biodegradation of p-aniline. The concentration of CaCl₂ was adjusted when the alginate gelled, and the alginate to yuzu peel cellulose ratio was tuned. The immobilized material-embedded bacteria help achieve the best degradation effect. Bacteria are embedded during the process of the degradation of aniline wastewater, and the functionalization of the cellulose/sodium alginate-immobilized material results in unique surface structure performance. The performance of the prepared system is better than that of the single sodium alginate-based material characterized by a large surface area and good mechanical properties. The degradation efficiency of the system is improved significantly for the cellulose materials, and the prepared materials can potentially find applications in the field of bacteria-fixed technology.

Role of cycle duration on the formation of quinoline-degraded aerobic granules in the aspect of sludge characteristics, extracellular polymeric substances and microbial communities

This study investigated the culture and characteristics of quinoline-degraded aerobic granular sludge (AGS) under 8-h and 12-h cycle duration. According to results, the cultivation of an 8-h cycle duration enhanced the growth of quinoline-degraded AGS, as well as the settleability of sludge and the retention of biomass. Quinoline can be removed from mature AGS at a rate of more than 90%, but it is removed at a rate slightly higher when the AGS are cultured for 12-h. Compared to 12-h cycle duration, 8-h cycle duration result in a greater increase in the production of extracellular polymeric substances, particularly extracellular proteins. In these two systems, Acidovorax and Paracoccus dominated the quinoline degrading bacteria. In addition, analysis by non-metric multidimensional scaling (based on Bray-curtis distance) showed significant differences of community structure between the two reactors. Clostridia and Acidaminobacter are different bacteria with an 8-h cycle duration compared to 12 h. Relative abundance of nitrogen metabolism genes based on PICRUSt2 prediction, which explain the better total nitrogen removal for an 8-h cycle duration compared to a 12-h cycle duration. Finally, the KEGG pathway was analyzed in order to confirm the results of the microbial analysis.

Bioaugmentation of quinoline-degrading bacteria for coking wastewater treatment: performance and microbial community analysis

Ochrobactrum sp. XKL1, previously found to have the ability to efficiently degrade quinoline, was bioaugmented into a lab-scale A/O/O system to treat real coking wastewater. During the bioaugmentation stage, the removal of quinoline and pyridine of the O1 tank could be enhanced by 9.88% and 7.96%, respectively. High-throughput sequencing analysis indicated that the addition of XKL1 could significantly affect the alteration of microbial community structure in the sludge. In addition, the relative abundance of Ochrobactrum has demonstrated a trend of increasing first followed by decreasing with the highest abundance of 7.87% attained on the 94th day. The bioaugmentation effects lasted for about 14 days after the strains was inoculated into the reactor. Although a decrease in the relative abundance of XKL1 was observed for a rather short period of time, the bioaugmented A/O/O system has been proven to be more effective in the removal of organic pollutants than the control. Hence, the results of this study indicated that the bioaugmentation with XKL1 is a feasible operational strategy that would be able to enhance the removal of NHCs in the treatment of coking wastewater with complex composition and high organic concentrations.

Dynamic characteristics of AHLs-secreting strain Aeromonas sp. A-L2 and its bioaugmentation during quinoline biodegradation

AIMS

In order to probe a more environmentally friendly method of pollutant treatment based on microbial bioaugmentation and quorum sensing (QS) effects.

METHODS AND RESULTS

The dynamic characteristics and QS effects of the acylated homoserine lactones (AHLs)-secreting strain Aeromonas sp. A-L2 (A-L2), which was isolated from the activated sludge system, was discussed. According to the liquid chromatography-mass spectrometry results, N-butyryl-homoserine lactone (C4-HSL) and N-hexanoyl-homoserine lactone (C6-HSL) were the major AHLs secreted by strain A-L2, and the swarming of strain Ochrobactrum sp. LC-1 (LC-1) was induced by these compounds. The extracellular polymeric substance secretion of the strain LC-1 was mainly led by C6-HSL, and the biofilm formation ability was mainly influenced by C6-HSL or C4-HSL (60 μg l^-1 ). The optimal AHLs secretion conditions of strain A-L2 were also studied. Drawing support from the AHLs-secreting strain A-L2 during quinoline degradation by strain LC-1, the degradation time was greatly shortened.

CONCLUSIONS

Hence, AHLs-secreting strain A-L2 can be useful as an AHLs continuous supplier during bioaugmentation and pollutant biodegradation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The bioaugmentation process of strain A-L2 on quinoline biodegradation based on QS effects would lay a certain theoretical and practical significance for large-scale applications.