International Scholarly Research Notices / 2014 / Article / Tab 2

Research Article

Use of Nonspecific, Glutamic Acid-Free, Media and High Glycerol or High Amylase as Inducing Parameters for Screening Bacillus Isolates Having High Yield of Polyglutamic Acid

Table 2

Extracellular amylase: protease activity and PGA production by Bacillus strains.

Parameter/property Bacillus  licheniformis T.Bacillus  licheniformis F.Bacillus  subtilis
24 h48 h24 h48 h24 h48 h

Amylasea units/mL broth 5000 67444200599539005578
Proteaseb units/mL broth425042564272
Amylase: protease: 24 h, 48 h1201341001079376
PGA (g/L)c in broth media with sodium citrate + glycerol (10, 40 g/L)11 (±3.4)22 (±1.2)6 (±1.3)
PGAc on solid media containing glucose (10–20 g/L)++(+)(+)
PGA productionc on media containing starch (5–20 g/L) and amylase activityd detected−, A−, A−, A−, A+, A+, A
PGA productionc on synthetic media containing starch (10 g/L), glucose (2.5 g/L); Amylased detected+, A+, A−, A−, A+, A +, A
PGA productionc on synthetic media containing starch (10 g/L), glucose (2.5 g/L), NaCl (10–100 g/L); Amylased+, A+, A−, A−, A+, A+, A
PGA productionc on synthetic media containing skimmed milk 20% v/v, pH 4–8; Protease detectede+, P+, P+, P+, P+, P+, P

Amylase/ bProtease assay:  Bacillus  subtilis (nonmucoid strain) and Bacillus T. and F. were inoculated in 1% starch broth or 1% skimmed milk broth and incubated at 37°C and amylase/protease activity was assayed.
cProduction medium (pH = 7): all substrates were added to Bushnell and Hass synthetic medium base (composition g/L: MgSO4 0.2, CaCl2 0.02, FeCl3 0.05, K2HPO4 1, KH2PO4 1, NH4NO3 1, and agar 25.
+/(+) = PGA present/variable. Values in parentheses are the standard deviation. − = PGA absent.
dA = amylase activity using starch agar (white/brown zone of hydrolysed starch visible after addition of Lugol’s iodine solution).
eP = protease activity (clear zone against turbid background of skimmed milk agar).