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
(a) Effect of physiological state of cells of Bacillus T. on production of PGAa in non glutamic acid containing media. (b) Effect of glutamic acid supplementation on yield of PGAa by Bacillus strains.
Inoculum medium (broth)
Inoculum age (h)
Vegetative cells present/2 cm2 square smear
Sporulated cells present/2 cm2 square smear
Polymerc (g/l) in broth (Inoculum used: 4% v/v)
Polymerc (g/l) in broth (Inoculum used: 20% v/v)
With glutamic acid (20 g/l)
Without glutamic acid
PGA producing culture
PGA on solid medium
PGA in broth (g/l)c
Polymer was either observed on solid medium as mucoid colonies (+) or extracted from broth cultures incubated on rotary shaker (180 rpm) using 3x volumes of acetone. Values are of dry weight of precipitated polymer, SD in parentheses.
bProduction medium: 20 g sodium citrate/l, 40 g glycerol/l in Bushnell and Hass medium base (pH 7). For solid medium 25 g agar/l was added.
cFor broth culture, 50 mL medium in 250 mL Erlenmeyer flasks was inoculated (6% inoculum v/v after centrifugation and discarding supernatant) with culture (OD = 1) and incubated for 24 to 96 h at 30°C. Polymer was extracted using 3x volumes of acetone, dried at 60°C.