Culture and spray-drying of Tsukamurella paurometabola C-924: stability of formulated powders

Abstract

The nematocidal agent, Tsukamurella paurometabola C-924, was cultured in a 300 l bioreactor. Spray-dried formulations of this microorganism were prepared using sucrose. At an outlet temperature 62 degrees C, survival rates between 12 and 85% were reached with sucrose up to 10% (w/w). The stability study of the powders showed that the best storage condition was at 4 degrees C under vacuum. A new method for the calculation of cell death order for bacteria stored at low temperatures was developed. Powders stored under vacuum showed an Arrhenius behavior in relation to cell death kinetics.

Towards a maximal cell survival in convective thermal drying processes

“…In relation to the effect of oxygen, for the same storage period, storage under vacuum gives substantially better retention in the cell activity than that without vacuum (i.e., directly exposed to air) (Chavez & Ledeboer, 2007;Hernandez et al, 2007). In contrast, the use of oxygen-scavenging agents during storage did not show significant effect in protecting cell viability (Chavez & Ledeboer, 2007;Wang et al, 2004).…”

“…A strain with better heatand osmotic-resistance improves the survival ratio by 1-2 fold after thermal drying (Corcoran et al, 2004;Fu & Etzel, 1995;Lian et al, 2002;Simpson, Stanton, Fitzgerald, & Ross, 2005;Sunny-Roberts & Knorr, 2009). Some strains that have been reported to show a survival ratio more than 90% after drying include Tsukamurella paurometabola C-924 (Hernandez et al, 2007), Enterococcus faecium M74 (Millqvist-Fureby, Malmsten, & Bergenstahl, 2000), L. plantarum CFR 2191 (Reddy et al, 2009), Lactobacillus salivarius CFR 2158 (Reddy et al, 2009) (Gardiner et al, 2000), L. salivarius CTC 2197 (Silva, Carvalho, Teixeira, & Gibbs, 2002) and 10 strains in the Lactococcus garviae and Lactobacillus murinus species, originally isolated from porcine blood (Zamora, Carretero, & Pares, 2006).…”

“…Besides trehalose and RSM, other components that have shown protective effects on maintaining cell viability during thermal drying include sucrose (Hernandez et al, 2007;Leslie et al, 1995;Linders, de Jong, Meerdink, & van't Riet, 1997;Oldenhof, Wolkers, Fonseca, Passot, & Marin, 2005), sorbitol (Linders, de Jong, et al, 1997), maltose (Linders, de Jong, et al, 1997), mannitol (Efiuvwevwere, Gorris, Smid, & Kets, 1999), maltodextrin (Oldenhof et al, 2005;Reddy et al, 2009), and gum acacia (Desmond et al, 2002). Starch, on the other hand, was reported to be a less effective carrier in protecting the cell viability during spray drying (O'Riordan, Andrews, Buckle, & Conway, 2001).…”

“…At higher storage temperature such as 37°C, greater loss of cell viability has been observed (Gardiner et al, 2000;Hernandez et al, 2007;Kearney et al, 2009;Riveros et al, 2009;Strasser et al, 2009;Sunny-Roberts & Knorr, 2009;Teixeira, Castro, Malcata, et al, 1995), whereas a storage temperature of 4°C could prolong the storage time up to 1 year without significant loss of cell viability . The mechanism of the loss of cell viability at elevated temperature is probably the natural degradation of life-essential macromolecules, considering that in vitro lipids and proteins undergo oxidation and denaturation, respectively, during prolonged storage period.…”

Dry flowable formulations of antagonistic Bacillus subtilis strain T429 by spray drying to control rice blast disease

“…These facts have stimulated researches on environmental-friendly strategies to control rice blast, such as applying biological control agents and discovering new pesticide formulations. Biological control of rice blast is a valuable alternative to the use of chemical pesticides, and many bacterial 3 formulations have been developed to combat rice blast in developing countries (Prabavathy et al, 2006;Krishnamurthy and Gnanamanickam, 1998;Armando et al,2007;Wiwattanapatapee et al,2013) . Bacillus subtilis can produce a broad array of antifungal lipopeptides, making this species a biological control agent (Ongena and Jacques, 2008 Dry flowable formulations contain inert ingredients, which prolong the shelf life and increase the efficacy of the products.…”