Pseudomonas putida Isolation and Quantification by Real-Time PCR in Agricultural Soil Biodegradable Mulching

Abstract

To reduce the plastic waste problem in agriculture, biodegradable plastic (BP) mulch films have become of key importance thanks to their biodegradability and beneficial effects on crops. However, at present, BPs cannot always replace conventional plastics, because biodegradation is governed by many biotic and abiotic factors under field conditions. This research aimed at isolating and identifying, from soil particles directly attached to the surface of BP samples, the microorganisms responsible of degradation through a combined approach based on biodegradation and molecular tests. For this purpose, a field trial within a Mediterranean apricot orchard was carried out to study the biodegradation of a commercial BP mulch with respect to a no-BP, a conventional apricot management, following the standard agricultural practices, and a subterranean clover cover cropping, either incorporating or leaving its dead mulches on the soil surface. After BP film appeared visibly degraded in field, we isolated from soil particles attached to the polymer surface, a mesophilic bacterium with certain degradative potential assessed by plate and liquid assays, identified by sequencing as Pseudomonas putida. Quantitative real time PCR analysis showed the P. putida was significantly more abundant in PB plots than the other plot treatments. These preliminary results are potentially applicable to accelerate the degradation of BP mulch films and decrease the plastic pollution in agriculture.

Effect of Long-Term Biodegradable Film Mulch on Soil Physicochemical and Microbial Properties

“…At present, some studies have made corresponding progress. For instance, Fontanazza et al [ 60 ] isolated and identified the mesophilic bacterium Pseudomonas putida from soil particles and found that the bacterium Pseudomonas putida was responsible for the degradation of biodegradable plastic. This may lead to the use of plastic-degrading microorganisms for amendments to the soil where plastics need to be degraded or to accelerate the degradation process.…”

Biodegradation of Typical Plastics: From Microbial Diversity to Metabolic Mechanisms

“…P. aeruginosa isolated from sewage water-contaminated surface soil incubated in nutrient broth (NB) medium for one month PP showed a weight loss of 5.37% [ 48 ]. Moreover, other species of the Pseudomonas , such as Pseudomonas citronellolis [ 49 ], Pseudomonas putida [ 50 ], Pseudomonas alcaligenes [ 51 ], and Pseudomonas fluorescens [ 52 ], have also been shown to degrade different types of plastics.…”