The Less Expensive Choice: Bacterial Strategies to Achieve Successful and Sustainable Reciprocal Interactions

Cold-resistant performance and the promoted development of functional community with flexible metabolic patterns in a Biofilm Bio-Nutrient Removal (BBNR) system amended with supplementary carbon source for phosphorus recovery

The need for recovery of phosphorus (P) from wastewater has accelerated the retrofitting of existing bio-nutrient removal (BNR) processes into bio-nutrient removal-phosphorus recovery processes (BNR-PR). A periodical carbon source supplement is needed to facilitate the P-recovery. But the impact of this amendment on the cold resistances of the reactor and the functional microorganisms (for nitrogen and phosphorus (P) removal/recovery) are still unknown. This study presents the performances of a biofilm BNR process with a carbon source regulated the P recovery (BBNR-CPR) process operating at different temperatures. When the temperature was decreased from 25 ± 1 °C to 6 ± 1 °C, the system total nitrogen and total phosphorus removals and the corresponding kinetic coefficients decreased moderately. The indicative genes of the phosphorus-accumulating organisms (e.g., Thauera spp. and Candidatus Accumulibacter spp.) increased significantly. An increase of Nitrosomonas spp. genes aligned to polyhydroxyalkanoates (PHAs), glycine, and extracellular polymeric substance synthesis were observed, which was probably related to cold resistance. The results provide a new vision for understanding the advantages of P recovery-targeted carbon source supplementation for constructing a new type of cold-resistant BBNR-CPR processes.

Influence of Flagellin Polymorphisms, Gene Regulation, and Responsive Memory on the Motility of Xanthomonas Species That Cause Bacterial Spot Disease of Solanaceous Plants

Increasingly, new evidence has demonstrated variability in the epitope regions of bacterial flagellin, including in regions harboring the microbe-associated molecular patterns flg22 and flgII-28 that are recognized by the pattern recognition receptors FLS2 and FLS3, respectively. Additionally, because bacterial motility is known to contribute to pathogen virulence and chemotaxis, reductions in or loss of motility can significantly reduce bacterial fitness. In this study, we determined that variations in flg22 and flgII-28 epitopes allow some but not all Xanthomonas spp. to evade both FLS2- and FLS3-mediated oxidative burst responses. We observed variation in the motility for many isolates, regardless of their flagellin sequence. Instead, we determined that past growth conditions may have a significant impact on the motility status of isolates, because we could minimize this variability by inducing motility using chemoattractant assays. Additionally, motility could be significantly suppressed under nutrient-limited conditions, and bacteria could "remember" its prior motility status after storage at ultracold temperatures. Finally, we observed larger bacterial populations of strains with flagellin variants predicted not to be recognized by either FLS2 or FLS3, suggesting that these bacteria can evade flagellin recognition in tomato plants. Although some flagellin variants may impart altered motility and differential recognition by the host immune system, external growth parameters and gene expression regulation appear to have more significant impacts on the motility phenotypes for these Xanthomonas spp.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.