GROWTH OF BACTERIAL BIOFILM ON ELECTROSPUN POLYCAPROLACTONE NANOFIBROUS SCAFFOLD FOR AGRICULTURAL USES

Increasing world population and limitation of land areas for agricultural uses have induced agrochemical industries to invest huge amounts of economic resources in developing fertilisers to improve crop yields and match human nutritional needs. The excessive use of these agrochemicals and the detrimental effects of intensive crop managements, however, have great impact on environment and human health. These results have been driving the attention of stakeholders and governments towards more environmentally friendly approaches (organic farming, use of biofertilisers, etc.). It is known that microbial populations interact with plants to support their growth [1]. Bacteria in ecosystems (e.g. soil) prefer to live in organised structures associated to surfaces termed biofilms [2], where microbial populations play most of their functions (organic matter degradation, mineral weathering, pollutant degradation, etc.). One of the main advantages of biofilm frameworks is their resistance to nutrient-deficient conditions, antimicrobial agents and environmental stresses (common in soil). Electrospinning is a powerful technology capable of producing fibres in the range of tens of nanometres to few micrometres, which can be used to create 2D and 3D structures of fibrous scaffolds. The exceptional increase in specific surface area, typical of nanofibrous fabrics, provides this technology enormous potential in creating materials with specific features for several applications, where an extensive interactive surface is required (medicine, environment, health care, textile, energy, etc.). Electrospinning can provide, indeed, textures suitable for cell adhesion, proliferation, and differentiation (fuel cells, medicine) [3,4]. The first goal of this study was then to create an electrospun nanofibrous scaffold suitable for the microbial growth of a specific bacterial strain selectively isolated for its capacity of supporting plant growth (PGPR activities). The following target was the development of a proper biofilm on such fabric, which was investigated and monitored over an 11 day-period, through the different phases of adhesion, growth and detaching. The viability and microbial activity of bacterial population in the biofilm were tested in respiration tests performed over the incubation period. The long-term (7 months) maintenance of viability and activity of biofilms, i.e. compatible with storage periods in dry conditions suitable for future commercial and agronomic managements, were also assessed. Results of these tests are here discussed.