Production of bacterial cellulose by Gluconacetobacter sacchari using dry olive mill residue

Bacterial Cellulose (BC), produced by many bacteria specially those belonging to the Gluconacetobacter genus, is a very peculiar cellulose form that bears unique mechanical and structural properties that can be exploited in numerous applications. However, the production costs of BC are very high because of the use of quite expensive culture media. In this sense, the purpose of this work was to evaluate the possibility of use residues from the olive oil production industry as nutrient and carbon source for the production of BC by Gluconacetobacter sacchari. The dry olive mill residue (DOR) was submitted to water extraction at 40 and 100 °C (DOR40 and DOR100) and to hydrolysis with H2SO4 1M (DOR100H) in order to obtain sugar rich aqueous extracts to be used for BC production. The BC production obtained without addiction of any type of nutrients was 0.81 g L−1 for DOR40 and 0.85 g L−1 for DOR100 after 96 h incubation, which corresponded respectively to 32 and 34% of the production achieved with conventional HS culture medium (around 2.5 g L−1). In order to enhance the production of BC, the residues were supplemented with nitrogen (N) and phosphate (P) sources to overcome possible nutritional limitations. It was verified an increase on the BC production between 21.5% (N8 P4,5) and 43.2% (N1 P8) when compared with no supplementation. These are promising results to overcome high BC production costs.