Impact of spray‐drying on the pili of Lactobacillus rhamnosus GG

Abstract

Summary The preservation of the viability of microorganisms in probiotic formulations is the most important parameter ensuring the adequate concentration of live microorganisms at the time of administration. The formulation and processing techniques used to produce these probiotic formulations can influence the preservation of the microbial viability. However, it is also required that the bacteria maintain their key probiotic capacities during processing, formulation and shelf life. In this study, we investigated the impact of spray‐drying on different cell wall properties of the model probiotic strain Lactobacillus rhamnosus GG, including its adherence to intestinal epithelial cells. The dltD gene knock‐out mutant, L. rhamnosus GG CMPG5540, displaying modified cell wall lipoteichoic acids, showed significantly increased colony‐forming units after spray‐drying and subsequent storage under standard conditions compared to wild‐type L. rhamnosus GG. In contrast, disruption of the biosynthesis of exopolysaccharides or pili expression did not impact survival. However, spray‐drying did significantly affect the adherence capacity of L. rhamnosus GG. Scanning electron microscopy confirmed that the pili, key surface factors for adherence to intestinal cells and mucus, were sheared off during the spray‐drying process. These data thus highlight that both the functionality and viability of probiotics should be assessed during the spray‐drying process and subsequent storage.

Lactic acid bacteria as probiotics for the nose?

“…Both studies thus highlight the feasibility for topical administration of LAB in the URT, but also pinpoint that proper selection of probiotic strains is essential. In addition to possible strain-specific effects, also other considerations should be addressed, such as the dose and formulation of the probiotic strains (Broeckx et al, 2017;Kiekens et al, 2019;Jokicevic et al, 2020). According to the definition, an 'adequate amount' of the probiotic is needed; however, the set-up of dose-response curves for probiotics is difficult (Ouwehand, 2017) and clinical studies on probiotic dose-response curves in the URT are currently lacking.…”

Shaping the Future of Probiotics and Prebiotics

“…Understanding strain phenomics and fluxomics with big data and machine learning may also help mastering product efficacy and stability in various applications [131]. Furthermore, beyond simple probiotic viability measures, the integrity of extracellular structures, enzymatic activities, or other effector molecules may help to assess probiotic functionality in the final application [132], provided such candidate markers are able to demonstrate a robust role in probiotic efficacy [132][133][134].…”

Probiotics and prebiotics in clinical tests: an update

“…The following two large trials challenge recommendations for LGG in AGE and raise the issue of strain-specific probiotic effects 6, 8, 9 or alteration of LGG by technological processing leading to the loss of pili 10 . A multicenter Canadian RCT randomly assigned children hospitalized with AGE to probiotic treatment with a commercial mixture of L. rhamnosus and Lactobacillus helveticus versus placebo 11 .…”

“…An MA of 23 RCTs comprising nearly 4000 patients described a reduction of AAD from 19% in placebo to 8% in probiotic-treated patients 21 . The ESPGHAN working group for probiotics/prebiotics recently questioned the practice of pooling different probiotic strains together for MAs 6 and suggested that probiotic effects against AAD may be strain-specific 22 or even depend on the probiotic preparation technique (LGG with or without pili; 10 ). Only two probiotics—LGG and S. boulardii —were tested in more than one RCT.…”