Comparative proteomics analysis to evaluate the influence of varying culture conditions on a planktonic freshwater dwelling bacterium, Polynucleobacter asymbioticus that belongs to the class Gammaproteobacteria. In the present study, a type strain Polynucleobacter asymbioticus strain QLW-P1DMWA-1T (= DSM 18221 = CIP 10981) was cultured in triplicates in sterile UV-permeable polyethylene bags (~35% permeability; Whirl-Pak®, Nasco). Culturing was carried out at 4°C, 26°C and 26° C plus 30 minutes of ultraviolet radiation exposure two times a day using 100W ARIMED® B UV lamps (Cosmedico®, Germany). We have applied mass spectrometry based large-scale screening of proteins to investigate to better understanding of the survival nature of this microbe.