Effects of pH on lignin and cellulose degradation by Streptomyces viridosporus
Lignocellulose degradation by Streptomyces viridosporus results in the oxidative depolymerization of lignin and the production of a water-soluble lignin polymer, acid-precipitable polymeric lignin (APPL). The effects of the culture pH on lignin and cellulose metabolism and APPL production by Streptomyces viridosporus are reported. Dry, ground, hot-water-extracted corn (Zea mays) lignocellulose was autoclaved in 1-liter reagent bottles and inoculated with 50-ml volumes of Streptomyces viridosporus cells suspended in buffers of specific pH (pH 6.0-9.2 at 0.4 pH unit intervals). Four replicates of inoculated cultures and of uninoculated controls at each pH were incubated as solid-state fermentations at 37 C. After 6 weeks of incubation the precent loss of lignocellulose, lignin, and carbohydrate and the amount of APPL produced were determined. Optimal lignocellulose degradation, as shown by substrate weight loss, was observed in the pH range of 8.4 to 8.8. Only minor differences were seen in the Klason lignin, carbohydrate, protein, and ash contents of the APPLS produced by cultures at each pH. The effects of pH on the degradation of a spruce (Picea pungens) (/sup 14/C-lignin)lignocellulose and a Douglas fir (Pseudotsuga menziesii) (/sup 14/C-glucan)lignocellulose were also determined at pH values between 6.5 and 9.5 (0.5 pH unit intervals). The incubations were carried out for 3 weeks at 37 degrees C with bubbler-tube cultures. The percentage of inital /sup 14/C recovered as /sup 14/CO/sub 2/, /sup 14/C-labeled water-soluble products, and (/sup 14/C) APPL was then determined. The mineralization of lignin and cellulose to CO/sub 2/ was optimal at pH 6.5 and 7.0, respectively. However, the optimum for lignin and cellulose solubilization was pH 8.5, which correlated with the pH 8.5 optimum for APPL production.
- Research Organization:
- Univ. of Idaho, Moscow
- OSTI ID:
- 6928008
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 52:3; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140504* -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
AUTOCLAVES
BACTERIA
BIOCONVERSION
BIODEGRADATION
BIOSYNTHESIS
CARBOHYDRATES
CELLULOSE
CEREALS
CHEMICAL REACTIONS
DECOMPOSITION
DEPOLYMERIZATION
FERMENTATION
FIRS
GRASS
LIGNIN
MAIZE
METABOLISM
MICROORGANISMS
ORGANIC COMPOUNDS
PH VALUE
PLANTS
POLYMERS
POLYSACCHARIDES
SACCHARIDES
SPRUCES
STREPTOMYCES
SYNTHESIS
TREES
WEIGHT MEASUREMENT