Study of the Bacterial Load in a Gelatine Production Process Focussed on Bacillus and Related Endosporeforming Genera

Abstract

Gelatine is an animal protein with many industrial applications. Previous studies pointed out that endosporeforming bacteria, belonging to the genus Bacillus or related genera, might contaminate and survive the production process of gelatine, leading to products of low quality and safety. The aim of this study is to determine the bacterial diversity of contaminants isolated from a gelatine production chain with emphasis on aerobic endosporeforming bacteria. Contaminants were isolated from samples taken at five crucial points along two different production lines of a gelatine production process and from water supplies used for extraction and cooling. Gaschromatographic methyl ester analysis of fatty acids was performed to differentiate isolates at the genus level. Apart from members of the genus Bacillus or related endosporeforming genera, also members of Salmonella, Kluyvera, Staphylococcus, Burkholderia, Enterococcus, Pseudomonas, Yersinia, Streptococcus and Brevundimonas could be detected. Isolates identified as belonging to Bacillus and related endosporeforming genera were further characterised by gelatinase tests, rep-PCR and 16S rDNA sequencing. All these isolates showed the ability to liquefy gelatine. Endosporeforming isolates were assigned to Bacillus licheniformis, B. fumarioli, members of the B. cereus group, B. badius, B. coagulans, B. subtilis, Brevibacillus agri, Alicyclobacillus acidocaldarius and a yet undescribed Paenibacillus species.