Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2024Diatom Communities in the Littoral Sediments of the Robert Island's Lakes, South Shetland Islands, Antarctica
Akar, Bulent; Güney, Aysegul; Özkan, Korhan; Avci, Utku; Kandemir, Raif
The study area is situated at Robert Island, which is located in the South Shetland Islands in the northwest of the Antarctic Peninsula. The diatom samples were taken as part of the Turkish Antarctic Expedition (TAE-II) which took place between March and April 2018. The samples were collected from the surface of sediments (c. 5 cm) at a depth of approximately 20 cm, 50-100 cm from the littoral zones of an inland glacial lake (L1) and three coastal lakes (L2, L3 and L4) situated on glacier-free area on Robert Island. The main objective of this study was to reveal the diversity and the abundance of diatom communities in the littoral sediments of the lakes on Robert Island. The lakes were shallow and oligotrophic freshwater lakes, although the coastal lagoons had a high conductivity and nutrient concentration. Twenty-six diatom taxa belonging to Achnanthes (1), Fragilaria (1), Frustulia (1), Gomphonema (1), Halamphora (1), Hantzschia (1), Hippodonta (1), Humidophila (2), Luticola (3), Melosira (1), Nitzschia (4), Pinnularia (3), Planothidium (2), Psammothidium (2), Stauroneis (1) and Stephanopterobia (1) were identified in the samples from these lakes. The coastal lake L2 showed the highest richness of diatom communities among the in studied lakes, with 21 identified taxa.
- MakaleAçık Erişim2020RP-HPLC-UV Analysis of the Phenolic Compounds, Antimicrobial Activity Against Multi-Drug Resistant Bacteria and Antioxidant Activity of Fruit and Seed of Diospyros lotus L.
Akar, Zeynep; Karakurt, Aylin; Okumus, Funda; Cinemre, Sedanur; Duzgun, Azer Ozad; Akar, Bulent; Can, Zehra
The object of the present study was to investigate the antioxidant, antimicrobial activity and phenolic compounds of fruit and seeds of Diospyros lotus L. The fruits consumed by humans as nutrients were harvested from the plants that grow naturally in the province of Trabzon-Akçaabat, Eastern Black Sea Region of Turkey. The antioxidant activities of fruit and seeds of Diospyros lotus were determined by using four methods (% DPPH radical scavenging activity, FRAP antioxidant power determination, CUPRAC reducing antioxidant activity and total phenolic content (TPC) in five different proportion of methanol-water extracts. All extracts of fruit and seeds of D. lotus analyzed through whole antioxidant analysis methods showed significant antioxidant activity. In addition, antimicrobial activity of fruit and seeds extracted with DMSO was determined against seven standard bacteria and three multi-drug resistance clinical strains. Although fruit extracts did not have the antimicrobial activity against bacteria, seeds showed antimicrobial effect to both standard strains (Gram-negative and Gram-positive) and antibiotic resistance clinical isolates (Klebsiella pneumoniae carrying blaKPC, Acinetobacter baumannii, harboring blaOXA-23 gene and resistance to colistin, and multi-drug resistant Pseudomonas aeruginosa). MICs’ value of plant seed extracts for standard strains was 0.75-25 mg/mL and antibiotic resistant clinical bacteria were 12.5 and 25 mg/mL. Additionally, phenolic compounds in methanol extracts of fruit and seeds were also determined in by HPLC using 19 standards. Gallic acid and chrysin phenolic compounds were the major phenolic compounds in fruit and seeds, respectively.