Formulation development of the biocontrol agent Bacillus subtilis strain CPA-8 by spray-drying

Abstract

Aims: To prepare commercially acceptable formulations of Bacillus subtilis CPA‐8 by spray‐drying with long storage life and retained efficacy to control peach and nectarine brown rot caused by Monilinia spp. Methods and Results: CPA‐8 24‐h‐ and 72‐h‐old cultures were spray dried using 10% skimmed milk, 10% skimmed milk plus 10% MgSO4, 10% MgSO4 and 20% MgSO4 as carriers/protectants. All carriers/protectants gave good percentages of powder recovery (28–38%) and moisture content (7–13%). CPA‐8 survival varied considerably among spray‐dried 24‐h‐ and 72‐h‐old cultures. Seventy‐two hours culture spray dried formulations showed the highest survival (28–32%) with final concentration products of 1·6–3·3 × 109 CFU g−1, while viability of 24‐h‐old formulations was lower than 1%. Spray‐dried 72‐h‐old formulations were selected to subsequent evaluation. Rehydration of cells with water provided a good recovery of CPA‐8 dried cells, similar to other complex rehydration media tested. Spray‐dried formulations stored at 4 ± 1 and 20 ± 1°C showed good shelf life during 6 months, and viability was maintained or slightly decreased by 0·2–0·3‐log. CPA‐8 formulations after 4‐ and 6 months storage were effective in controlling brown rot caused by Monilinia spp. on nectarines and peaches resulting in a 90–100% reduction in disease incidence. Conclusions: Stable and effective formulations of biocontrol agent B. subtilis CPA‐8 could be obtained by spray‐drying. Significance and Impact of the Study: New shelf‐stable and effective formulations of a biocontrol agent have been obtained by spray‐drying to control brown rot on peach.

Spray-dried powder ofBacillus megateriumfor control of rice sheath blight disease: Formulation protocol and efficacy testing in laboratory and greenhouse

“…Although the spray-dried product of Bacillus sp., especially B. subtilis (Yánez-Mendizábal et al 2012), has been devised and tested to control insect pests and plant disease, a spraydried product of B. megaterium has not previously been formulated and tested for the control of rice sheath blight disease.…”

“…Lian et al (2002) have also attributed the high survival of bifidobacteria to 10% w/v skim milk powder. A stable and effective formulation of B. subtilis CPA-8 was obtained by spray-drying in the presence of 10% skimmed milk powder and PVP as carriers and protecting agents (Yánez-Mendizábal et al 2012).…”

“…This technique has also been used for preparing starter cultures in the agricultural industry (Johnson and Etzel 1995) and for other bio-products (To and Etzel 1997a, b). The product of the spray-drying method that contained high numbers of viable microorganisms is desirable for use in various commercial applications, such as preserving food (Ananta et al 2005), agricultural products (Horaczek and Viernstein 2004), pharmaceuticals (Boza et al 2004;Zamora et al 2006) and to control plant disease (Yánez-Mendizábal et al 2012).…”

Dry formulations of the biocontrol agent Candida sakeCPA‐1 using fluidised bed drying to control the main postharvest diseases on fruits

“…By contrast, phosphate buffer at 25 °C is cheaper. Yánez‐Mendizábal et al . obtained lower viabilities by rehydrating spray‐dried Bacillus subtilis CPA‐8 cells with skimmed milk than with other rehydration media.…”

The science, development, and commercialization of postharvest biocontrol products

“…Only a small number of microorganisms, however, are able to survive the high temperatures used in this drying process. Only biocontrol agents that are able to produce heat-resistant endospores, such as B. subtilis CPA-8, are suitable for spray drying Yánez-Mendizábal et al, 2012a). Fluidized bed-drying is a costeffective method of drying that can be used to dry heat-sensitive microorganisms because the drying temperatures are relatively low.…”