Effects of N source and nitrification pretreatment on growth of Arthrospiraplatensis in human urine

Culture of Arthrospira platensis (Spirulina platensis) in human urine was investigated to get valuable biomass. NO3-N was the proper N source, in comparison with other N source, including urea, NH4-N and NO2-N. As a result, aerobic nitrification of human urine was performed, with above 93.6% nitrification percentage finally achieved with total-N (TN) load of 46.52 mg/(L·d), in which Arthrospira platensis was successfully grown. The main compositions of the obtained biomass are close to those in Zarrouk medium. Thus, it is possible to culture Arthrospira platensis in nitrified human urine for food production within bioregenerative life support systems (BLSSs).     

Abundance and composition of ammonia-oxidizing bacteria and archaea in different types of soil in the Yangtze River estuary

Tidal flats are soil resources of great significance. Nitrification plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments. We determined the abundance as well as composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in different soils during land reclamation process. The abundance of AOA was higher than that of AOB in farm land and wild land while AOA was not detected in tidal flats using real-time polymerase chain reaction (PCR). The different abundances of AOB and AOA were negatively correlated with the salinity. The diversities of AOB and AOA were also investigated using clone libraries by amplification of amoA gene. Among AOB, nearly all sequences belonged to the Nitrosomonas lineage in the initial land reclamation process, i.e., tidal flats, while both Nitrosomonas and Nitrosospira lineages were detected in later and transition phases of land reclamation process, farm land and wild land. The ratio of the numbers of sequences of Nitrosomonas and Nitrosospira lineages was positively correlated with the salinity and the net nitrification rate. As for AOA, there was no obvious correlation with the changes in the physicochemical properties of the soil. This study suggests that AOB may be more import than AOA with respect to influencing the different land reclamation process stages.