Author(s): Santana, C. A. ; Piccirillo, C. ; Pereira, S. I. A. ; Pullard, R. C. ; Lima, S. M. ; Castro, P. M. L.
Date: 2019
Persistent ID: http://hdl.handle.net/10400.14/28351
Origin: Veritati - Repositório Institucional da Universidade Católica Portuguesa
Subject(s): Phosphorous; Solubilisation; Hydroxyapatite; Phosphate solubilising bacteria (PSB); By-products valorisation; Fish scales; Tilapia
The increased use of fertilisers is a well-known problem; linked to this, there is an always higher demand for phosphorus (P). Because of this, it is crucial to use P from all possible sources and, if necessary, turn it into a soluble form, available for plants/crops. In this paper we report the use of aerobic phosphate solubilising bacteria (PSB) on the scales of the tilapia (Coptodon rendalli) fish, a waste from the food industry; this is the first time that PSB were employed on fish scales to mediate the available P. The scales were calcined to 700 °C to obtain a nanoscale powdery material (more easily solubilised), made of hydroxyapatite, Ca10(PO4)6(OH)2, a calcium phosphate with very low solubility. Seventeen different PSB strains were tested for their ability to solubilise phosphate (commercial tricalcium phosphate - TCP) and hydroxyapatite from fish scale (FSHA). The best performing bacterial strain (Acidovorax oryzae ZS 1–7) led to a P solubilisation more than 60 times higher than the negative control – at 325 mg/L, almost 40% of the available P was solubilised – one of the highest increased efficiencies reported for PBS. Such solubilisation was linked to a decrease of the pH to more acidic values of about 4. The strain ZS 1–7 showed higher P solubilisation efficiency with fish-derived FSHA than with commercial TCP. This approach showed a promising strategy for the valorisation of residues of the fish industry, turning them into a source of P, to be used for sustainable agriculture.
