MSc Thesis Defense:Zeynep Sude Aksu,ISOLATION AND CHARACTERIZATION OF MESOPHILIC BACTERIA FROM YAZLIK ILICASI THERMAL SPRING WATER AND EVALUATION OF THEIR BIOFERTILIZER POTENTIAL USING BRASSICA JUNCEA (L.) CZERN. AS A MODEL PLANT
ISOLATION AND CHARACTERIZATION OF MESOPHILIC BACTERIA FROM YAZLIK ILICASI THERMAL SPRING WATER AND EVALUATION OF THEIR BIOFERTILIZER POTENTIAL USING BRASSICA JUNCEA (L.) CZERN. AS A MODEL PLANT
Zeynep Sude Aksu
Molecular Biology, Genetics & Bioengineering, MSc. Thesis, 2025
Thesis Jury:
Prof. Levent Öztürk (Thesis Supervisor)
Dr. Zaeema Khan (Thesis Co-Supervisor)
Asst. Prof. Stuart James Lucas
Prof. Ali Coşkan
Date & Time: December 18th, 2025 – 12:40 PM
Place: FENS L058
Zoom Link: https://sabanciuniv.
Keywords: thermal spring, sulfur-oxidizing bacteria, sulfur mineralization, biofertilizer potential, Brassica juncea (L.) Czern.
Abstract
Geothermal springs are home to a diverse range of extremophilic microorganisms. Depending on the local physicochemical conditions, thermophilic and mesophilic species can simultaneously thrive. Despite their potential, these environments and microbial diversity remain largely unexplored in Türkiye. Low sulfur availability in agricultural soils significantly impacts crop yield and nutritional quality, particularly in arid and alkaline regions that make up much of Türkiye’s croplands. This study focuses on isolating and identifying mesophilic sulfur-oxidizing bacteria (SOB) from a geothermal spring in the Gölcük district of Kocaeli. The primary objective is to evaluate their potential as biofertilizers to improve sulfur availability and promote the growth of Brassica juncea (L.) Czern. A multi-phase methodology was employed, including site sampling, sample collection, bacterial isolation, identification, and biochemical testing. The selected bacterial isolate was subsequently evaluated for its effects on root development. This evaluation was carried out using an experimental setup that included two treatment groups, three formulations of Murashige and Skoog medium, and an appropriate pH indicator ratio. The results indicated that SOB isolate promoted root elongation and germination rates. Furthermore, biochemical experiments revealed that the isolates exhibited notable metabolic versatility and environmental resilience, making them promising candidates for developing biofertilizers, especially for use in sulfur-deficient, degraded, or alkaline soils. This research contributes to unravelling the potential of extremophiles in plant growth promotion, advancement of the use of microbes in sustainable agricultural practices and expands national expertise in extremophile microbiology, paving the path for future microbial applications in crop production systems.