Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ultrasonic pretreatment of excess sludge can improve its aerobic digestibility, leading to enhanced sludge reduction. In order to understand the mechanisms of this improvement, sludge flocs were divided into four layers, i.e. (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS) and (4) pellet. Extracellular proteins, polysaccharides and five types of hydrolytic enzymes (protease, alpha-amylase, alpha-glucosidase, alkaline-phosphatase and acid-phosphatase) from sludge flocs were investigated to determine their influence on sludge aerobic digestion after ultrasonic pretreatment. Results suggested that most of the extracellular enzymes (except alpha-amylase) were present in pellet and TB-EPS layers, with minor quantities detected in LB-EPS and slime layers, and almost none detected in bulk solution. As for alpha-amylase in sludge flocs, most of it (52.6%) was also mainly bound with pellet; however, the rest of it was dispersed nearly uniformly throughout the sludge flocs. Ultrasonic pretreatment enhances enzymatic activities and promotes the shifts of extracellular proteins, polysaccharides and enzymes from inner layers of sludge flocs, i.e., pellet and TB-EPS, to outer layers, i.e., slime, to increase the contact and interaction among extracellular proteins, polysaccharides and enzymes that were originally embedded in the sludge flocs, resulting in improved efficiency in aerobic digestion. The optimum ultrasonic pretreatment conditions had a lasting time of 10min and density of 3 kWL(-1) at the frequency of 20 kHz. With the optimum ultrasonic pretreatment, the sludge reduction for TSS in aerobic digestion was 42.7% in which the part of 11.8% was removed by the ultrasonic pretreatment, compared with 20.9% for control, after an aerobic digestion time of 10.5d.
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PMID:Extracellular proteins, polysaccharides and enzymes impact on sludge aerobic digestion after ultrasonic pretreatment. 1808 40

The effects of biosurfactant alkyl polyglycosides (APG) on the hydrolysis and acidification of waste activited sludge including dosage of APG and hydrolysis time were investigated. It was found that APG reduced the tension of sludge hydrolysate, promoting sludge hydrolysis. The concentrations of SCOD, protein and soluble carbonhydrate reached the maximum within 12 h at the optimal dosage of 0.2 g x g(-1) TSS, rising from 4 280.2, 1 122.9 and 246.5 mg x L(-1) to 6481.1, 1 639.3 and 1205.8 mg x L(-1), respectively, and the short-chain fatty acids (SCFAs) concentration increased from 1309.9 mg x L(-1) to 2221.6 mg x L(-1) simultaneously, the percentage of individual SCFA changed as well, and the time required to reach the maximal SCFAs concentration will be prolonged with the increase of dosage. With increasing APG dosage, a-glucosidase relative enzyme activities increased from 1.5 to 2.5, while protease relative enzyme activity increased from 1.4 to 1.9 at low dosages and decreased to 1.5 at high dosages. Regardless of the biosurfactant APG, alpha-glucosidase and protease enzyme activities decreased along with the hydrolysis time. The pH showed a tendency of first decreasing and then increasing.
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PMID:[Enhanced hydrolysis and acidification of waste activated sludge by alkyl polyglycosides]. 2488 90