T Berninger1, B Mitter1, C Preininger1. 1. Center for Health and Bioresources, Austrian Institute of Technology GmbH, Tulln, Austria.
Abstract
AIMS: Producing dry, zeolite-based granular and powder inoculants of the Gram-negative, plant growth-promoting bacterium Paraburkholderia phytofirmans PsJN. Key aspects were maintenance of cell viability during desiccation and throughout storage at ambient conditions. METHODS AND RESULTS: Twenty additives and exopolysaccharide (EPS) produced by PsJN were screened for conserving cell viability of PsJN in air-drying and lyophilization. Suitable combinations (e.g. skimmed milk + air-drying) increased survival of PsJN up to 100 000-fold and maintained it for >7 months. EPS performed as good as skimmed milk during air-drying, but was second-rank regarding shelf life. Combinations of zeolite, skimmed milk and gelatin as a film-forming agent were extruded and processed into granules and powders, both displaying relatively stable viability for over 4 weeks at ambient conditions. Gelatin promoted brittleness of zeolite-based inoculants. CONCLUSIONS: Viability of highly sensitive PsJN was successfully conserved in dry formulations, taking into account the interplay between carrier, protectants, drying method and coating agent. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to provide ways of maintaining viability of PsJN during desiccation stress and to investigate the applicability of its EPS as a protectant, thus ultimately facilitating successful plant inoculation especially under field conditions.
AIMS: Producing dry, zeolite-based granular and powder inoculants of the Gram-negative, plant growth-promoting bacterium Paraburkholderia phytofirmans PsJN. Key aspects were maintenance of cell viability during desiccation and throughout storage at ambient conditions. METHODS AND RESULTS: Twenty additives and exopolysaccharide (EPS) produced by PsJN were screened for conserving cell viability of PsJN in air-drying and lyophilization. Suitable combinations (e.g. skimmed milk + air-drying) increased survival of PsJN up to 100 000-fold and maintained it for >7 months. EPS performed as good as skimmed milk during air-drying, but was second-rank regarding shelf life. Combinations of zeolite, skimmed milk and gelatin as a film-forming agent were extruded and processed into granules and powders, both displaying relatively stable viability for over 4 weeks at ambient conditions. Gelatin promoted brittleness of zeolite-based inoculants. CONCLUSIONS: Viability of highly sensitive PsJN was successfully conserved in dry formulations, taking into account the interplay between carrier, protectants, drying method and coating agent. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to provide ways of maintaining viability of PsJN during desiccation stress and to investigate the applicability of its EPS as a protectant, thus ultimately facilitating successful plant inoculation especially under field conditions.
Authors: Muhammad Sohaib; Zahir Ahmad Zahir; Muhammad Yahya Khan; Muhammad Ans; Hafiz Naeem Asghar; Sanaullah Yasin; Fahad N I Al-Barakah Journal: Saudi J Biol Sci Date: 2019-12-31 Impact factor: 4.219