Abstract:
Calcium precipitation and biofilm formation in halophilic bacteria were investigated
in the current study. The strain SMK (Bacillus licheniformis) was isolated from plant rhizosphere and
and AQ-1 (Alcaligenes faecalis) from marble crushing soil in Lahore. Bacterial growth, biofilm
formation and CaCO3 precipitation of both strains was determined under varying stress (pH,
temperature, agitation and salinity). Soil aggregation was investigated under salt stress (NaCl and
MgSO4). Results showed that pH 8.0, temperature 42°C, 1.5 M salt (NaCl and MgSO4) stress without
agitation was favorable for biofilm formation. Both strains were able to precipitate CaCO3 in media
specially at margins of colonies in AQ-1. Effervescence of crystals with addition of concentrated HCl
showed confirmatory results. Stereomicroscopic analysis of aggregates in inoculated soil and sand
showed precipitation under salt stress. SMK (Bacillus licheniformis) showed high aggregation in soil.
From the results, it was concluded that these indigenous strains have potential for sustainable
agriculture by improving disturbed soil.
