PRELIMINARY SCREENING OF BIODEGRADATION ACTIVITY IN BACTERIAL STRAINS ISOLATED FROM MICROPLASTICS IN THE BARENTS SEA

In the research conducted as part of the Third National Arctic Scientific Expedition (TASE-III), bacterial
diversity in microplastics collected from the Barents Sea was investigated using a manta trawl net.
Initially, to facilitate molecular analysis of the strains, the microplastics were incubated in 400 mL of
Luria-Bertani broth at 150 rpm for one day. Following incubation, the broth was filtered through 0.22
μm filter papers employing a membrane filtration method, and the resulting filtrate was cultured on
several media, including R2A Agar, Aeromonas Agar Base, Cetrimide Agar, Actinomycete Selection
Agar, Thiosulfate Citrate Bile Salt Agar, Sulphate Reducing Bacteria Agar, and Zobell Marine Agar.
These cultures were subsequently incubated at temperatures between 4°C and 30°C for 24 to 72 hours.
To identify the species of the isolates, bacterial DNA was first extracted. This extracted DNA was
amplified using the universal primers 27F and 1492R, and the PCR products were then sequenced via
Sanger sequencing by an external service provider. A total of 80 isolates were identified during the
project, with 40 of them already presented at another conference. The remaining 40 isolates will be
presented at this upcoming conference. For assessing the pre-degradation of the strains against
polyethylene (PE) polymer, a preliminary screening was conducted. In this process, 100 mL of MSM
was inoculated with a 1% bacterial inoculum in 250 mL Erlenmeyer flasks, to which 0.5 g of commercial
PE was added. The flasks were incubated at 25°C for 28 days. After this incubation period, the strains
exhibiting the highest absorbance values were identified by measuring the optical density at 600 nm
with a spectrophotometer. The study revealed species from genera such as Priestia, Bacillus,
Psychrobacter, Staphylococcus, Pseudomonas, Arthrobacter, Pseudoalteromonas, Rhodococcus,
Paenibacillus, Agrococcus, Micrococcus, Acinetobacter, Kocuria, and Carnobacterium. Preliminary
results from the biodegradation screening indicated that the highest biodegradation rate, recorded at
1.77, was for isolate D1R30.1, identified as Bacillus albus. In contrast, the lowest biodegradation level,
with a value of 1.21, was for isolate D1Z30.5B2, associated with Psychrobacter nivimaris. This study
was supported by the TUBITAK KUTUP 1001 Project, numbered 122G270. The authors thank
TUBITAK for their support.