Anaerobic reduction of high-polarity nitroaromatic compounds by electrochemically active bacteria: Roles of Mtr respiratory pathway, molecular polarity, mediator and membrane permeability.

Electrochemically active bacteria (EAB) are effective for the bioreduction of nitroaromatic compounds (NACs), but the exact reduction mechanisms are unclear yet. Therefore, 3-nitrobenzenesulfonate (NBS) was used to explore the biodegradation mechanism of NACs by EAB. Results show that NBS could be anaerobically degraded by Shewanella oneidensis MR-1. The generation of aminoaromatic compounds was accompanied with the NBS reduction, indicating that NBS was biodegraded via reductive approach by S. oneidensis MR-1. The impacts of NBS concentration and cell density on the NBS reduction were evaluated. The removal of NBS depends mainly on the transmembrane electron transfer of S. oneidensis MR-1. Impairment of Mtr respiratory pathway was found to mitigate the reduction of NBS, suggesting that the anaerobic biodegradation of NBS occurred extracellularly. Knocking out cymA severely impaired the extracellular reduction ability of S. oneidensis MR-1. However, the phenotype of ΔcymA mutant could be compensated by the exogenous electron mediators, implying the trans-outer membrane diffusion of mediators into the periplasmic space. This work provides a new insight into the anaerobic reduction of aromatic contaminants by EAB.

Extraordinary expansion of a Sorangium cellulosum genome from an alkaline milieu.

Complex environmental conditions can significantly affect bacterial genome size by unknown mechanisms. The So0157-2 strain of Sorangium cellulosum is an alkaline-adaptive epothilone producer that grows across a wide pH range. Here, we show that the genome of this strain is 14,782,125 base pairs, 1.75-megabases larger than the largest bacterial genome from S. cellulosum reported previously. The total 11,599 coding sequences (CDSs) include massive duplications and horizontally transferred genes, regulated by lots of protein kinases, sigma factors and related transcriptional regulation co-factors, providing the So0157-2 strain abundant resources and flexibility for ecological adaptation. The comparative transcriptomics approach, which detected 90.7% of the total CDSs, not only demonstrates complex expression patterns under varying environmental conditions but also suggests an alkaline-improved pathway of the insertion and duplication, which has been genetically testified, in this strain. These results provide insights into and a paradigm for how environmental conditions can affect bacterial genome expansion.

[Relationship between recurrence and metastasis of gastric cancer and expression of EGFR, IL-6R, PCNA, and DI].

BACKGROUND AND OBJECTIVE: The primary reasons for the failure were recurrence and metastasis in the treatment of gastric cancer. This study was designed to investigate the distributive regularity of EGFR, IL-6R, PCNA, DI and the diploid in the gastric cancer patients with recurrence and metastasis, to provide reliable basis to judge whether it has metastasis before operation and recurrence post operation. METHOD: Immunohistochemistry SP method and image analyzer (Fegulgen staining) were used to test the EGFR, IL-6R, PCNA, DI and the diploid in 199 patients with gastric cancer, 20 cases with normal gastric mucous membrane, and 20 cases of atypical hyperplasia. RESULTS: The level of expression of EGFR was higher in the patients with metastasis and residual gastric cancer(61.11%, 66%, 66.67%) than in the patients with other cancers, normal gastric mucous membrane, atypical hyperplasia(47.83%, 0%, 35%) (P < 0.01); In the distribution form of DNA diploid, the rate of non-diploid cells was remarkably higher in the patients with metastasis and residual gastric cancer(56.9 +/- 13.3% vs 12.8 +/- 6.3%, 0%, 12.2), and so is the DNA index (2.91 +/- 0.33 vs 2.17 +/- 0.29), but the rate of 2C cells is lower(43.8 +/- 12.9 vs 10.2 +/- 7.5, P < 0.01). CONCLUSION: EGFR, DI, and the diploid are valuable targets for judging metastasis and recurrence of gastric cancer before and after operation.