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Table 2 Dry cell weight (g L−1), crude biosurfactant yield (g L−1), oil spreading (cm), emulsification index (%), and surface tension (mNm−1) obtained for Bacillus atrophaeus 5-2a grown in mineral salt solution with different nitrogen sources at 30 °C for 5 days

From: Production of lipopeptide biosurfactants by Bacillus atrophaeus 5-2a and their potential use in microbial enhanced oil recovery

Nitrogen source Dry cell weight (g L−1) Crude biosurfactant yield (g L−1) Oil spreading (cm) Emulsification index (%) Surface tension (mN m−1)
Beef extract 0.64 ± 0.021e 0.47 ± 0.014c 16.5 ± 0.10f 59.50 ± 0.34c 27.64 ± 0.028b
Peptone 0.87 ± 0.057d 0.66 ± 0.028ab 18.8 ± 0.10b 59.47 ± 0.36c 26.65 ± 0.057d
Corn steep liquor 0.63 ± 0.028e 0.42 ± 0.085c 14.2 ± 0.16 g 10.41 ± 0.57d 29.51 ± 0.035a
Urea 0.99 ± 0.028c 0.78 ± 0.028a 19.2 ± 0.10a 60.54 ± 0.38ab 26.43 ± 0.021e
NH4Cl 1.41 ± 0.014a 0.55 ± 0.071bc 16.9 ± 0.10e 59.34 ± 0.18c 27.64 ± 0.014b
(NH4)2SO4 1.22 ± 0.014b 0.66 ± 0.085ab 17.2 ± 0.12d 61.16 ± 0.25a 27.42 ± 0.092c
NaNO3 0.85 ± 0.0071d 0.73 ± 0.042a 17.6 ± 0.12c 61.23 ± 0.59a 27.38 ± 0.099c
KNO3 0.47 ± 0.014f 0.53 ± 0.099bc 16.7 ± 0.16e 60.14 ± 0.19bc 27.60 ± 0.057b
  1. Values are presented as the mean ± standard deviation (n = 3). Different superscript letters within a column indicate significant differences (P < 0.05) by Duncan’s multiple range test