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P837 The common food additives sodium sulfite and polysorbate 80 have a profound inhibitory effect on the commensal, anti-inflammatory bacterium Faecalibacterium prausnitzii: the ENIGMA study

J. J. Jimenez Loayza1,2, E. M. Berendsen*1,2, J-J. Teh1,2, E. C. Hoedt1,2,3, J. Zhang4,5, Q. Liu4,5, A. L. Hamilton6, A. Wilson-O'Brien6, G. L. Trakman6, W. Lin4,5, W. Tang4,5, J. Ching4,5, L. M. H. Or4,5, J. J. Sung4,5, J. Yu4,5, S. C. Ng4,5,7, M. A. Kamm6, M. Morrison1,2

1The University of Queensland Diamantina Institute, Faculty of Medicine, Brisbane, Australia, 2Translational Research Institute, Brisbane, Australia, 3University College Cork, APC Microbiome Ireland, Cork, Ireland, 4The Chinese University of Hong Kong, Department of Medicine and Therapeutics, Hong Kong, Hong Kong, 5The Chinese University of Hong Kong, LKS Institute of Health Sciences, Institute of Digestive Disease and State Key Laboratory of Digestive Diseases, Hong Kong, Hong Kong, 6The University of Melbourne and St Vincent's Hospital, Melbourne, Department of Medicine and Department of Gastroenterology, Melbourne, Australia, 7The Chinese University of Hong Kong, Centre for Gut Microbiota Research, Hong Kong, Hong Kong

Background

Faecalibacterium prausnitzii may be a key protective bacterium, and useful therapeutically to attenuate inflammation and promote gut homeostasis in Crohn’s disease (CD). However, the reasons for its variable persistence during active disease and recovery remain unknown. We hypothesise F. prausnitzii is constrained by dietary factors that might promote inflammation; and food additives have been implicated recently in microbial changes that promote inflammation. We have investigated how 8 common food additives affect the growth kinetics of 3 strains of F. prausnitzii.

Methods

F. prausnitzii A2-165, KLE1255, and AHMP21 were cultured using a habitat-simulating medium supplemented with 0.2% (wt/vol) glucose (M2G), or M2G prepared to contain 0.1% (wt/vol) of either sodium sulphite, aluminium silicate, carrageenan, carboxymethylcellulose, polysorbate 80, saccharin, sucralose, or aspartame, intended to approximate concentrations found in food. The 3 F. prausnitzii strains were also grown with M2G medium and once these cultures had reached mid-exponential phase of growth, either sodium sulfite or polysorbate 80 was added to the cultures to 0.1% (wt/vol). Growth was monitored by optical density measurements.

Results

Figure 1 shows all 3 strains were strongly inhibited by sodium sulfite and polysorbate 80. The growth rates of all 3 F. prausnitzii strains were not affected by the other food additives, with the exception of a small but significant decrease for strain KLE1255 in the presence of sucralose (p < 0.05). Cell yield of strain A2-165 was unaffected by the remaining food additives, whereas the cell yield of strain AHMP21 was reduced by saccharin (p < 0.05); and by sucralose and saccharin for strain KLE1255 (p < 0.05). Growth of all 3 F. prausnitzii strains was immediately arrested when sodium sulphite was added to mid-exponential phase cultures; the effects of polysorbate 80 were more variable and probably cell-density dependent.

Figure 1. Effect of food additives (0.1% [wt/vol] final concentration) on the growth kinetics of F. prausnitzii strains A2-165 (A), AHMP21 (B), and KLE1255 (C). Data points are the mean ± SEM of optical density measurements at 600 nm (n = 6).

Conclusion

Sodium sulfite and polysorbate 80 have strong inhibitory effects on F. prausnitzii growth. Exclusion of such additives from the diet may be critical to improved Crohn’s disease activity or prevention. This work is supported by The Leona M. and Harry B. Helmsley Charitable Trust.