Effect of lyophilization on Pseudomonas sp. viability and biodegradation activity of terephthalic acid

Pseudomonas sp. which used hydrocarbon biodegradation of wastewater was isolated active sludge of waste water treatment unit of petrochemical wastewater plant. In this study, effect of different protective agents and lyophilization techniques were compared on Pseudomanas sp. viability and biodegradation activity after lyophilization . Pseudomonas sp. was cultured in Nutrient Broth medium at 27 ºC. The bacterial cells were added in lyophilization vials with sterile protective agents: skim milk, saccharose, silicagel individually and in different combination. The vials were placed in a lyophilisation chamber and lyophilized for 24 hours. Vials cap sealed under vacuum and vials were stored in the dark at +4°C. Bacterial cells were reactivated (1.-3.-5.-15.-30. weeks) and viability counts were observed. The bacteria were supplemented with single hydrocarbon compound as sole carbon source (100 mg/L TFA) in Bushnell–Hass Broth and measured biodegradation activity of HPLC (High Performance Liquid Chromotography). The initial concentration used was 2x10⁸ cfu/ml. Bacterial survival rates showed that Pseudomonas sp. Freeze drying techniques with skim milk as protective medium could still reach 1,5x10⁶ at 4ºC after 30 weeks. Biodegradation activity of Pseudomonas sp. remained same before and after lyophilization.