Screening of ammonia-degrading bacteria to reduce ammonia content in the manure of laying hens

Abstract

This study aimed to screen probiotic candidates for the capacity to degrade ammonia content in the manure of laying hens. Seven bacteria previously isolated from broilers’ intestine were assigned to a completely randomized design. A fresh culture of each bacterial isolate was cultured to reach optical density at OD600:0.5. One ml suspension was inoculated into 100 ml samples (2g manure diluted in 100 ml of sterilized distilled water) and incubated for three days. Ammonia concentrations in each sample were measured daily using Ammonium/Ammonia-Test sera ammonia kits. The results showed that the ammonia concentration in all bacteria-treated samples was significantly lower than ammonia content in control, P<0.05). The average amount of ammonia in the control was 1.00±0.44 mg/l, while isolate I1-treated sample was 0.03±0.00 mg/l, isolate I2 0.02±0.00 mg/l, isolate I3 0.02±0.00 mg/l, isolate I4 0.04±0.01 mg/l, isolate I5 0.04±0.01 mg/l, isolate I6 0.02±0.01 mg/l and isolate I7 0.05±0.00 mg/l. The best three ammonia degrading capacity among the seven isolates were I2, I3, and I6. Based on the phenotypical characteristics, these bacteria were identified as Nitrosomonas sp. (I2), Nitrosobolus sp. (I3), and Nitrosococcus sp. (I6). Therefore, these three bacteria were recommended for probiotic candidates in laying hen.