Poly(L‐lactide)‐Degrading Activity in Various Actinomycetes

Abstract

The poly(L‐lactide) (PLA)‐degrading ability of actinomycetes obtained from culture collections was examined by the formation of clear zones on PLA‐emulsified agar plates. Using 41 genera (105 strains) of actinomycetes with phylogenetic affiliations based on 16S rRNA sequences, PLA degraders were found to be limited to members of the family Pseudonocardiaceae and related genera. They included Amycolatopsis, Saccharothrix, Lentzea, Kibdelosporangium, and Streptoalloteichus. A large number of PLA degraders were widely distributed within the genus Saccharothrix. Most strains forming clear zones on PLA‐emulsified agar plates also formed clear zones on silk fibroin agar plates. Saccharothrix species showed an ability to degrade PLA films and assimilate degradation products in liquid cultures. No significant change of the molecular weight and polydispersity (Mw/Mn) of the remaining film fragments was confirmed. After cultivation for two weeks, many irregular holes/pits on the surface of the film due to the colonization of microorganisms were observed by scanning electron microscopy.Scanning electron micrograph of the surface of PLA film: A. orientalis subsp. orientalis IFO 12362 after 14 d.magnified imageScanning electron micrograph of the surface of PLA film: A. orientalis subsp. orientalis IFO 12362 after 14 d.

A novel poly (L-lactide) degrading actinomycetes isolated from Thai forest soil, phylogenic relationship and the enzyme characterization

“…Our fi nding draws a distinction to the report of Jarerat et al (2002) that several actinomycetes limited to only family Pseudonocardiaceae and related genera were capable of degrading PLA. The taxonomic assignments of PLA-degrading actinomycetes were supported by the results of chemotaxonomic and phenotypic studies as shown in Table 1.…”

Isolation of bacteria from ectomycorrhizae of Tuber aestivum Vittad

“…In particular, we repeatedly failed to isolate the members of the actinobacterial genera Actinosynnema, Allokutzneria, Kibdelosporangium and Lentzea, the members of the suborder Pseudonocardineae which proved to positively correlate with the presence of T. aestivum in ectomycorrrhizae. In spite of the fact that Pseudonocardineae members are generally considered rare organisms in the nature (Jarerat et al 2002), our molecular data predict that Pseudonocardineae members represent significant portion of biomass of the root-associated microbial community. However, they either do not produce sufficient amounts of colony forming units necessary for isolation or cannot be cultivated using our methodology.…”

New Insight into Biodegradation of Poly (L-Lactide), Enzyme Production and Characterization

“…Among 13 isolates, strain T16-1 showed the highest PLAdegrading activity at 50C and identified as Actinomadura keratinilytica strain T16-1. This finding draw a distinction to the report of Jarerat et al (2002) that several actinomycetes limited only in the family Pseudonocardiaceae and related genera were capable of degrading PLA. Furthermore, strain T16-1 was further identified by Sukkhum et al (2009a).…”