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Anammox process has brought about cost-effective, eco-friendly, and innovative technologies to wastewater treatment by reducing the operational cost of treatment plants and decreasing greenhouse gas emissions. Titanium dioxide (TiO2), as one of the most prevalent nanoparticles (NPs) in the world, is being used in various consumer products and applications. In recent years, studies have focused on potential toxicological impacts of NPs on biological processes due to their endless production and consumption. In this context, the first time in the literature, 24 h acute TiO2 NPs exposure on Anammox process was investigated. Deterioration on anammox activity gradually increased with increasing applied TiO2 NPs concentration. At 300 mg/L exposure dose, nitrogen removal rate dramatically decreased to 37.09 ± 0.24 mgN/ gVSS.d and a severe inhibition (80.57% ± 1.17%) was observed. Among the several curve fit models, non-linear second order polynomial (quadratic) model was the best fit one with IC50 of 154 mg/L. Scanning electron microscope (SEM) images demonstrated the tendency of TiO2 NPs to aggregate and attach to the surface of the bacteria. Extracellular polymeric substance (EPS) response of anammox bacteria was also investigated and it was found that, the total EPS content gradually decreased by increasing TiO2 NPs concentration.

Nonylphenol (NP) is a bioaccumulative environmental estrogen that is widely used as a nonionic surfactant. We have previously examined short-term effects of NP on yeast cells using microarray technology. In the present study, we investigated the adaptive response of Saccharomyces cerevisiae BY4742 cells to NP exposure by analyzing genome-wide transcriptional profiles using RNA-sequencing. We used 2 mg/L NP concentration for 40 days of exposure. Gene expression analysis showed that a total of 948 genes were differentially expressed. Of these, 834 genes were downregulated, while 114 genes were significantly upregulated. GO enrichment analysis revealed that 369 GO terms were significantly affected by NP exposure. Further analysis showed that many of the differentially expressed genes were associated with oxidative phosphorylation, iron and copper acquisition, autophagy, pleiotropic drug resistance and cell cycle progression related processes such as DNA and mismatch repair, chromosome segregation, spindle checkpoint activity, and kinetochore organization. Overall, these results provide considerable information and a comprehensive understanding of the adaptive response to NP exposure at the gene expression level.

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The potential effects of nanoparticles (NPs) on biological treatment processes have become significant due to their increasing industrial applications. The purpose of this research was to investigate the self-recovery ability of anammox bacteria following to acute ZnO NPs toxicity. In this context, a 2-liter lab-scale anammox reactor was operated for 550 days to enrich the biomass required to the batch exposure tests. Anammox culture was firstly exposed to four different doses of ZnO NPs (50, 75, 100 and 200 mg/L) for 24 h. Then, the ZnO NPs were removed and self-recovery performance of the anammox bacteria was assessed by evaluating the nitrogen removal capacities for 72 h. Besides the nitrogen removal performance, extracellular polymeric substances (EPS) production was also detected to deeply understand the response of the enriched anammox culture against ZnO NPs exposure. The results revealed that, sudden and high load of ZnO NPs (100 and 200 mg/L) resulted in persistent impairment on the nitrogen removal performance of the enriched anammox culture. However, relatively lower doses (50 and 75 mg/L) caused deceleration of the nitrogen removal performance during the recovery period. In addition, EPS content in the reactor decreased along with escalating load of ZnO NPs.

Öz: Dünya atmosferinin ağırlıkça %75,5'ini, hacimce %78,06'sını oluşturan azot elementi ATP, klorofil, nükleik asitler, vitaminler gibi birçok önemli biyomolekülün yapısına katılmaktadır. Fakat azot gazı formunda (N 2) bulunan bu element, birincil üreticiler dahil canlılar için kullanılmaya elverişli formda değildir. Bu yüzden azot döngüsü yaşamın sürekliliğini sağlayan en önemli biyolojik proseslerden biridir. 1990'lı yılların sonunda anammox bakterilerinin keşfi ile birlikte azot döngüsü hakkındaki bulgular güncellenmiş olup, anammox uygulamaları günümüzde atık su arıtma tesislerinde kullanılan konvansiyonel nitrifikasyon/denitrifikasyon proseslerine alternatif bir teknoloji haline gelmiştir. Bu proses anoksik ortamda anammox bakterilerinin nitriti elektron alıcı olarak kullanarak amonyumu azot gazına dönüştürmesi olarak açıklanabilir. Şimdiye kadar, yedi anammox cinsi bulunmasına rağmen, saf kültürleri elde edilemediği için hepsine aday (Candidatus) statüsü verilmiştir. Buna ek olarak, bu bakteriler eşsiz metabolizmaları nedeniyle ekolojik araştırmalar ve moleküler biyoloji alanlarında bilimsel bir dönüm noktası olmuştur. Bu bağlamda, çalışmamızda anammox bakterilerinin büyümesi, hücre biyolojisi, moleküler mekanizması ile birlikte Anammox prosesinin çevre uygulmalarındaki rolü ve önemi detaylı olarak incelenmiştir.