Extracellular Polyhydroxyalkanoate Depolymerase by Acidovorax sp. DP5

Abstract

Bacteria capable of degrading polyhydroxyalkanoates (PHA) by secreting extracellular depolymerase enzymes were isolated from water and soil samples collected from various environments in Malaysia. A total of 8 potential degraders exhibited clear zones on poly(3-hydroxybutyrate) [P(3HB)] based agar, indicating the presence of extracellular PHA depolymerase. Among the isolates, DP5 exhibited the largest clearing zone with a degradation index of 6.0. The highest degradation activity of P(3HB) was also observed with depolymerase enzyme of DP5 in mineral salt medium containing P(3HB). Based on biochemical characterization and 16S rRNA cloning and sequencing, isolate DP5 was found to belong to the genus Acidovorax and subsequently named as Acidovorax sp. DP5. The highest extracellular depolymerase enzyme activity was achieved when 0.25% (w/v) of P(3HB) and 1 g/L of urea were used as carbon and nitrogen source, respectively, in the culture media. The most suitable assay condition of the depolymerase enzyme in response to pH and temperature was tested. The depolymerase produced by strain Acidovorax sp. DP5 showed high percentage of degradation with P(3HB) films in an alkaline condition with pH 9 and at a temperature of 40°C.

Enhanced degradation of polyhydroxyalkanoates (PHAs) by newly isolated Burkholderia cepacia DP1 with high depolymerase activity

“…Nevertheless, high P(3HB) depolymerase enzyme production was also achieved using other nitrogen sources on different bacterial species such as Acidovorax sp. DP5 (Urea) (Vigneswari et al 2015). It is interesting to note that different types of nitrogen varyingly affect microbial P(3HB) depolymerase production.…”

“…(Manna et al 1999) and Acidovorax sp. (Vigneswari et al 2015). The decrease in P(3HB) depolymerase enzyme production at high substrate concentration might be due to substratelevel inhibition such that the substrate concentration above optimum level as a rule inhibits the enzyme activity (Manna and Paul 2000).…”

“…Samples were collected from soil, sludge, lake and seawater. The isolation was done according to the method of Vigneswari et al (2015) with slight modification. A volume of 1 mL of water or 1.0 g of soil and sludge sample was enriched in the P(3HB) medium.…”

“…From the result, the P(3HB) depolymerase enzyme production by B. cepacia DP1 was higher than that obtained by Acidovorax sp. DP5 (3.0 U/mL) (Vigneswari et al 2015), Stenotrophomona smaltophilia (1.50 U/mL) (Sonal et al 2015).…”

“…Although various studies were published on the disintegration of SCL-PHAs and production of P(3HB) depolymerase enzymes in Acidovorax sp. DP5 (Vigneswari et al 2015), Comamonas sp. (Jendrossek et al 1993), Alcaligenes faecalis T1 (Yamashita et al 2001), Pseudomonas mendocina DSWY0601 (Wang et al 2012) and Arthrobacter sp.…”