Data from: Kinetics of calcite precipitation by ureolytic bacteria under aerobic and anaerobic conditions

The kinetics of urea hydrolysis (ureolysis) and induced calcium carbonate
(CaCO3) precipitation for engineering use in the subsurface was
investigated under aerobic conditions using Sporosarcina pasteurii (ATCC
strain 11859) as well as Bacillus sphaericus strains 21776 and 21787. All
bacterial strains showed ureolytic activity inducing CaCO3 precipitation
aerobically. Rate constants not normalized to biomass demonstrated
slightly higher rate coefficients for both ureolysis (kurea) and CaCO3
precipitation (kprecip) for B. sphaericus 21776 (kurea = 0.10 ± 0.03 h-1,
kprecip = 0.60 ± 0.34 h-1) compared to S. pasteurii (kurea = 0.07 ± 0.02
h-1, kprecip = 0.25 ± 0.02 h-1) though these differences were not
statistically significantly different. B. sphaericus 21787 showed little
ureolytic activity but was still capable of inducing some CaCO3
precipitation. Cell growth appeared to be inhibited during the period of
CaCO3 precipitation. TEM images suggest this is due to the encasement of
cells and was reflected in lower kurea values observed in the presence of
dissolved Ca. However, biomass re-growth could be observed after CaCO3
precipitation ceased, which suggests that ureolysis-induced CaCO3
precipitation is not necessarily lethal for the entire population. The
kinetics of ureolysis and CaCO3 precipitation with S. pasteurii were
further analyzed under anaerobic conditions. Rate coefficients obtained in
anaerobic environments were comparable to those under aerobic conditions,
however no cell growth was observed under anaerobic conditions with NO3-,
SO42- and Fe3+ as potential terminal electron acceptors. These data
suggest that the initial rates of ureolysis and ureolysis-induced CaCO3
precipitation are not significantly affected by the absence of oxygen but
that long-term ureolytic activity might require the addition of suitable
electron acceptors. Variations in the ureolytic capabilities and
associated rates of CaCO3 precipitation between strains must be fully
considered in subsurface engineering strategies that utilize microbial
amendments.