Interaction between poly-3-hydroxybutyrate-co-3-hydroxyvalerate and a denitrifying Pseudomonas strain

Abstract

In a laboratory-scale system, dentrification activity of a heterotrophic microbial starter culture changed when different lots of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P(HB-co-HV)) were used as the solid carbon source in the heterotrophic denitrification reactor. In this study, possible influences of physical and chemical properties of commercially produced P(HB-co-HV) (Biopol) on biofilm formation and metabolic activity of a denitrifying starter culture were investigated. These parameters indicate the polymers' suitability for the application as the matrix substance in the bioreactor. No differences in microstructure were detected between the different lots of polymers. Growth inhibitory effects by chemical additives were found in the case of triacetine, which was included as a plasticizer in seven of eight tested lots. The amount of hydroxyvaleric acid in the polymer was not assumed to affect denitrification activity. Relevant differences could be detected regarding primary adhesion of the starter culture Pseudomonas sp. strain 2nIII. It showed good adsorption properties to hydrophobic substances with a dependence on precultivation conditions. Pseudomonas sp. strain 2nIII degraded poly-3-hydroxybutyrate acid homopolymer and P(HB-co-HV) copolymers but was unable to break up poly-3-hydroxyvaleric acid. A possible reason for these findings is the substrate specifity of the polyhydroxyalkanoate depolymerase.

Members of the Family Comamonadaceae as Primary Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)-Degrading Denitrifiers in Activated Sludge as Revealed by a Polyphasic Approach

“…Of special interest is the fact that three of our isolates, strains KSP3, KSP4, and NA10B, together with the 1-chloro-4-nitrobenzene-degrading bacterium LW1 (29), formed a tight cluster distinct from any of the established genera of the family Comamonadaceae. Our phylogenetic data provide circumstantial evidence that this new group of isolates differs taxonomically from the PHBV-degrading denitrifying strains reported so far by other research groups (6,40,52) Culture-independent approaches to the community analysis Namely, FISH analyses with group-specific oligonucleotide probes showed that members of the ␤-Proteobacteria increased remarkably during acclimation to PHBV under denitrifying conditions in laboratory scale activated-sludge systems, accounting for more than 60% of the total population under fully acclimated conditions. This trend obtained from FISH probing is in good agreement with the results of quinone profiling.…”

“…This type of nitrogen removal process, called here the solid-phase denitrification process, may have some advantages, e.g., a constant supply of reducing power, no secondary organic pollution, and ease of operation. A promising solid substrate for denitrification is the bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) (6,30,40,52), which serves as the source of biodegradable plastic (4,17,34,50). The biodegradability of PHBV in natural environments has been extensively studied, and a number of PHBV-degrading bacteria have been isolated and characterized (1, 11, 38, 39, 41-43, 45, 55).…”

“…(40), and Pseudomonas sp. (6). Our previous study reported the isolation of a new denitrifying ␤-proteobacterium that exhibits a denitrification rate as high as 19 mg of NO 3 Ϫ -N removed h Ϫ1 g…”

Activity and Community Composition of Denitrifying Bacteria in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-Using Solid-phase Denitrification Processes

“…In this connection, several strains of PHB-and PHBV-degrading denitrifying bacteria have been isolated and characterized from activated sludge and PHA-utilizing SPD processes 3,[24][25][26]30,38) . A representative of PHB-degrading denitrifiers is Diaphorobacter nitroreducens 25) .…”

Column Experiment on Nitrate Purification with Polylactic Acid and Iron Powder

“…On the other hand, the use of artificial degradable organic compounds, i.e., biodegradable plastics for biological denitrification has been studied by many researchers (Biedermann et al 1997;Boley et al 2003;Hiraishi and Khan 2003;Kahn and Hiraishi 2001;Khan et al 2002;Müller et al 1992). Biodegradable plastics are decomposed to a small molecular weight by bacterial enzymatic degradation or by chemical hydrolysis (Doi and Steinbuchel 2002;Sudesh and Iwata 2008).…”