Alcaligenes aquatilis GTE53: Phosphate solubilising and bioremediation bacterium isolated from new biotope "phosphate sludge enriched-compost"

Ayoub Haouas; Cherkaoui El Modafar; Allal Douira; Saâd Ibnsouda-Koraichi; Abdelkarim Filali-Maltouf; Abdelmajid Moukhli; Soumia Amir

doi:10.1016/j.sjbs.2020.10.015

Alcaligenes aquatilis GTE53: Phosphate solubilising and bioremediation bacterium isolated from new biotope "phosphate sludge enriched-compost"

Saudi J Biol Sci. 2021 Jan;28(1):371-379. doi: 10.1016/j.sjbs.2020.10.015. Epub 2020 Oct 15.

Authors

Ayoub Haouas¹, Cherkaoui El Modafar², Allal Douira³, Saâd Ibnsouda-Koraichi⁴, Abdelkarim Filali-Maltouf⁵, Abdelmajid Moukhli⁶, Soumia Amir¹

Affiliations

¹ Laboratoire Polyvalent en Recherche et Développement, Faculté Polydisciplinaire, Université Sultan Moulay Slimane, Beni Mellal, Morocco.
² Laboratoire d'Agrobiotechnologie et Bioingénierie, Faculté des Sciences et Techniques, Université Cadi Ayyad, Marrakech, Morocco.
³ Laboratoire de Botanique Biotechnologie et de Protection des Plantes, Faculté des Sciences, Université Ibn Tofail, Kenitra, Morocco.
⁴ Laboratoire de Biotechnologie Microbienne et Molécules Bioactives, Faculté des Sciences et Techniques, Université Sidi Mohamed Ben Abdellah, Fès, Morocco.
⁵ Laboratoire de Microbiologie et Biologie Moléculaire, Faculté des Sciences, Université Mohammed V, Rabat, Morocco.
⁶ Unité de Recherche d'Amélioration génétique des plantes, Institut national de la Recherche Agronomique, Marrakech, Morocco.

Abstract

The isolation and identification of beneficial bacteria from the active phase of composting is considered to be a key bio-quality parameter for the assessment of the process. The aim of this work was the selection and identification of beneficial bacteria from a co-composting experiment of vegetable waste (VW), olive oil mill waste (O₂MW), and phosphate sludge (PS). Phosphate-solubilizing strains were isolated from the thermophilic phase using Pikovskaya (PVK) solid medium supplemented with tricalcium phosphate Ca3(PO4) (TCP) as the sole source of phosphorus (P). Therefore, the selected isolate Alcaligenes aquatilis GTE53 was tested to tolerate abiotic stresses (different levels of temperature, variable pH, high salinity and water stress). The isolate was also assessed for indole acetic acid (IAA) and siderophores synthesis, nitrogen fixation, phenol degradation and pathogens inactivation. The quality of the co-composting process was also investigated by monitoring the physico-chemical parameters. The obtained results showed that A. aquatilis GTE53 displayed a higher solubilization index of 2.4 and was efficiently dissolved, up to 162.8 and 247.4 mg·mL^-1 of inorganic phosphate from PS and phosphate rock (PR), respectively. A. aquatilis GTE53 exhibited siderophores and IAA release, along with atmospheric nitrogen fixation. In addition to that, A. aquatilis GTE53 showed a high resistance to heat and tolerance to acidic and alkaline pH, high salinity and water stress. Moreover, A. aquatilis GTE53 could degrade 99.2% of phenol from a high-concentrated medium (1100 mg·L^-1 of phenol) and can inactivate the most abundant pathogens in industrial wastes: Escherichia coli, Streptococcus sp., Salmonella sp., and Fusarium oxysporum albedinis. Analysis of temperature, pH, electrical conductivity, carbon/nitrogen (C/N) ratio, indicated successful co-composting. An efficient transformation of P to the available form and a great abatement of polyphenols, were also recorded during the process. The findings of this study will help to advance the understanding of A. aquatilis GTE53 functions and will facilitate its application to promote beneficial microbial organisms during composting, thus obtaining a high-quality product.

Keywords: Alcaligenes aquatilis; Bioremediation; Pathogens; Phenol degradation; Phosphate solubilisation.