Aerobic and Anaerobic Microbial Degradation of Poly-β-Hydroxybutyrate Produced by Azotobacter chroococcumстатья
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Аннотация:Food industry wastewater served as a carbon source for the synthesis of
poly-β-hydroxybutyrate (PHB) by Azotobacter chroococcum. The content of
polymer in bacterial cells grown on the raw materials reached 75%. PHB
films were degraded under aerobic, microaerobic, and anaerobic conditions
in the presence and absence of nitrate by microbial populations of soil, sludges
from anaerobic and nitrifying/denitrifying reactors, and sediment from
a sludge deposit site. Changes in molecular mass, crystallinity, and mechanical
properties of PHB were studied. Anaerobic degradation was accompanied
by acetate formation, which was the main intermediate utilized by
denitrifying bacteria or methanogenic archaea. On a decrease in temperature
from 20 to 5°C in the presence of nitrate, the rate of PHB degradation was
7.3 times lower. Under anaerobic conditions and in the absence of nitrate, no
PHB degradation was observed, even at 11°C. The enrichment cultures of
denitrifying bacteria obtained from soil and anaerobic sludge degraded PHB
films for a short time (3–7 d). The dominant species in the enrichment culture
from soil were Pseudomonas fluorescens and Pseudomonas stutzeri. The rate of
PHB degradation by the enrichment cultures depended on the polymer
molecular weight, which reduced with time during biodegradation