Ece Polat

Wastewater-based epidemiology (WBE) is a powerful method that allows community surveillance to identify diseases/pandemic dynamics in a city, especially in metropolitan areas with high overpopulation. This study investigated the detection and quantification of SARS-CoV-2 RNA in wastewater and sewage sludge in two different wastewater treatment plants (WWTPs) in Istanbul, the 5th largest city in the world, during the COVID-19 pandemic. Statistical analysis was performed to examine the relationships between SARS-CoV-2 concentrations and COVID-19 case numbers, seasonal variations, and key WWTP parameters, including total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD), using principal component analysis (PCA). SARS-CoV-2 N genes were analyzed in influent, treated effluent and sludge samples collected between June 2021 and January 2022 by reverse transcription–polymerase chain reaction (RT-qPCR). Viral genes were detected in 23 out of 26 influent wastewater samples (88%) and in 4 out of 26 secondary treated wastewater samples. SARS-CoV-2 RNA concentrations in influent samples ranged from 0 to 11,469 ± 551.2 genomic copies (GC)/mL for all viral genes analyzed (N1: 109.7 ± 46.6 − 11,228.9 ± 543.05 GC/mL and N2: 864.5 ± 82 − 11,469.6 ± 551.2 GC/mL). In secondary wastewater samples, SARS-CoV-2 RNA concentrations ranged from 665.23 ± 48.6 to 2,833.17 GC/mL, while sludge samples contained concentrations ranging from 138.7 ± 20.1 to 2,027.9 ± 97.2 GC/mL. The findings of this work demonstrate the feasibility of RT-qPCR for quantifying SARS-CoV-2 in wastewater and suggest a weak to moderate correlation between SARS-CoV-2 gene concentrations and confirmed COVID-19 and death cases in the community. A correlation was also observed between the number of GC per TP and COD for both the N1 (Pearson correlation coefficient: 0.949 for N1/TP and 0.986 for N1/COD) and N2 genes (Pearson correlation coefficient: 0.960 for N2/TP and 0.993 for N2/COD) in two WWTPs. The study highlights the potential of WBE as a COVID-19 surveillance tool and as an early warning and control system for SARS-CoV-2 infections.

"Solid waste can contain large amounts of plastic; most are not biodegradable. For this reason, the disposal of waste plastics is a critical issue for society and sustainable life. It is important to note that solid waste landfills are the most common method for disposing plastics. Nowadays, energy recovery from waste plastics is gaining importance due to the energy production potential of waste plastics. Thermal methods such as incineration, gasification and pyrolysis can be used to obtain energy from plastic waste, but the conversion of plastic waste into liquid fuels, including diesel and gasoline, is also being researched. Although these methods reduce the environmental impact of plastic waste and provide alternative energy sources, the recovery of high-value-added products in parallel with energy generation is also important to minimize emissions, ensure adequate waste treatment, and promote environmental sustainability. As an example, the burning potential of polystyrene, which comprises 22 percent of waste plastics, is compatible with the circular economy concept while simultaneously reducing petroleum fuel consumption by recycling high value-added materials such as polycarbonate and polyamide.. Through the use of polymer recycling in conjunction with energy recovery from waste plastics, environmentally friendly, cost-effective waste management can be achieved."

Müsilaj oluşumu, çeşitli biyolojik ve hidrolojik etkileşimleri içeren çok karmaşık bir olgudur. Müsilaj oluşumuna elverişli koşullar oşinografik değişimlerle gözlenebilirken, ortamda bulunan bakteriyel ve fitoplanktona dayalı aktiviteler de müsilaj oluşumunda etkin rol oynar. 17. yüzyıldan beri farklı denizlerde ve ekosistemlerde gözlenmiş müsilajın, mikrobiyal yapısı ve şekli de farklıdır. Bu durumu, müsilaj oluşumunun çoğunlukla taksona özgü olması ve kalınlığının ile dokusunun ise çevresel faktörlerden etkilenmesi ile açıklamak mümkündür. Müsilaj araştırmalarında baskın tür olarak çoğunlukla fitoplankterler karşımıza çıkmaktadır. Özellikle, ortamdaki yüksek organik madde miktarı ve nutrient miktarları, fitoplankton oluşumu ve mikroçevre oluşumunu tetiklemektedir ve suyun sıcaklık, akışkanlık, türbidite gibi bazı özellikleri müsilaj üretimini artırıcı etki göstermektedir. Bu derlemede, öncelikle çözünmüş organik madde (ÇOM) ve mikrobiyal popülasyonun agregat oluşturarak nasıl müsilaja dönüştüğünden bahsedilmiştir. Sonrasında, mikrobiyal ekoloji incelemelerinde müsilajın yapısında karşılaşılmış canlı grupları anlatılmıştır. Müsilaj bölgelerinde gözlenen baskın türler, vaka bilgileri ile detaylı olarak anlatıldıktan sonra, müsilaj oluşumu sonucu yaşamı olumsuz etkilenen canlılardan bazı örnekler verilmiştir.

Since Yarrowia lipolytica, an oily yeast, contains many valuable products as biomass, to increase its widespread use, it is very important to develop a sustainable production model. In this study, the production of high acid hydrolysate from sawdust biomass, which is produced in very high amounts in our environment, and the effect of these products on the growth efficiency of Yarrowia lipolytica were investigated. A preliminary statistical analysis was carried out to assess sugar production from sawdust by hydrolysis, which estimated 85% of total sugar recovery (TSR) using 96 g of sawdust, while TSR at the highest sawdust was as high as 79%. There was a higher loss in the recovery of C₅ sugars with acid and time. This study revealed that Y. lipolytica could grow with high biomass yields in varying hydrolysate concentrations, approaching yields achieved in synthetic glucose media. The maximum biomass obtained was 13 and 26 g in batch and airlift operations, respectively, using organic nutrients. Biomass and lipid yields from kinetic modeling provided a close approximation to the experimental yields performed on an airlift reactor. It was found that Y. lipolytica biomass cultivated on sawdust hydrolysates had significant lipid and protein compositions, as high as 29 and 38%, respectively.

Nitrogen stress can influence microalgae’s growth characteristics, and microalgae grown in nitrogen-deficient conditions may produce higher or lower levels of biotechnological products as a result of metabolic changes. In photoautotrophic and heterotrophic cultures, nitrogen limitation has been proven effective in promoting lipid accumulation. In spite of this, no study has demonstrated a significant correlation between lipid content and other biotechnological products such as bioactive compounds (BACs). This research examines a strategy for lipid accumulation as well as the potential production of BACs with antibacterial properties in parallel with that strategy. This concept involved the treatment of the microalga Auxenochlorella protothecoides with low and high concentrations of ammonium (NH₄⁺). This particular experiment reached a maximum lipid content of 59.5% using a 0.8 mM NH₄⁺ concentration, resulting in the yellowing of the chlorophyll levels. Agar diffusion assays were conducted to determine the antibacterial activity of different extracts derived from the biomass when stressed with different levels of nitrogen. Algal extracts prepared by a variety of solvents showed different levels of antibacterial activity against representative strains of both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria. Among the extracts tested, 500 mg/L ethyl acetate extract had the greatest antibacterial activity against Escherichia coli. In order to identify the components responsible for the extract’s antibacterial activity, fatty acid methyl ester (FAME) analysis was performed. It has been suggested that the lipid fraction may be a valuable indicator of these activities since some lipid components are known to possess antimicrobial properties. In this regard, it was found that the amount of polyunsaturated fatty acid (PUFA) significantly decreased by 53.4% under the conditions with the highest antibacterial activity observed.

Mutagenesis in microbial strains might result in robust strains with enhanced biofuel properties. Besides that, oleaginous microalgae, Auxenochlorella sp. with enhanced biomass and lipid content, can be a strong candidate for biodiesel production. In this context, a chemical mutagen called ethyl methane sulfonate (EMS) was screened at different concentrations. Considering that a lower survival rate can result in a higher mutation rate, an EMS concentration of 0.25M with 13 mins exposure time was selected as the optimum mutation condition. An acetyl-coenzyme A carboxylase (ACCase) inhibitor herbicide, tralkoxydim, was used as a selective environment to choose the mutant strains. Using an ACCase inhibitor herbicide would maintain a more desirable mutant strain that had the enhanced characteristics of biodiesel. Multi-scale comparisons between selected mutant strains and a wild strain revealed that by the time there was a remarkable decrease of 12.6% in the lipid content of the wild strain under the addition of Tralkoxydim (34.8%) compared to 39.8% in wild type, the lipid contents of the mutant strains remained higher. A remarkable increase by 1.50-fold and 1.33-fold in biodiesel fuel properties for Tralkoxydim-treated strains emphasizes that the ACCase synthesis pathway for lipid production is influenced by the stress factor that reaches the European biodiesel standards.