Enhancing the stress responses of probiotics for a lifestyle from gut to product and back again

Abstract

Before a probiotic bacterium can even begin to fulfill its biological role, it must survive a battery of environmental stresses imposed during food processing and passage through the gastrointestinal tract (GIT). Food processing stresses include extremes in temperature, as well as osmotic, oxidative and food matrix stresses. Passage through the GIT is a hazardous journey for any bacteria with deleterious lows in pH encountered in the stomach to the detergent-like properties of bile in the duodenum. However, bacteria are equipped with an array of defense mechanisms to counteract intracellular damage or to enhance the robustness of the cell to withstand lethal external environments. Understanding these mechanisms in probiotic bacteria and indeed other bacterial groups has resulted in the development of a molecular toolbox to augment the technological and gastrointestinal performance of probiotics. This has been greatly aided by studies which examine the global cellular responses to stress highlighting distinct regulatory networks and which also identify novel mechanisms used by cells to cope with hazardous environments. This review highlights the latest studies which have exploited the bacterial stress response with a view to producing next-generation probiotic cultures and highlights the significance of studies which view the global bacterial stress response from an integrative systems biology perspective.

Stress Physiology of Lactic Acid Bacteria

“…During transit through the GIT, several Lactobacillus spp. survive the low pH of the stomach (pH 2.0 to 4.0) and the subsequent exposure to bile salts and pancreatic juice in the duodenum (27). Lactobacillus spp.…”

“…They encounter a variety of stresses during production and use. Before a probiotic bacterium begins to fulfill its biological role in the gut, it must survive a battery of environmental challenges (27). Initially, probiotic bacteria must be processed in a suitable product form to enable oral consumption in adequate numbers, and then the bacteria must survive the harsh conditions imposed during passage through the GIT (451).…”

Survival of Lactobacillus rhamnosus GG during Simulated Gastrointestinal Conditions Depending on Food Matrix

“…The main gastrointestinal stress factors are considered to be the acidic environment of the stomach and the presence and effect of bile salts in the duodenum (Mills, Stanton, Fitzgerald, & Ross, 2011). Gorbach and Goldin (1989) showed that Lactobacillus rhamnosus GG decreased from 10 8 to 10 6 after 0.5 h at pH 2.5 in normal human gastric juice.…”

Profiles and technological requirements of urogenital probiotics

“…For example, microbial preadaptation at different temperatures or at different solute concentrations could increase the strain resistance to some stress conditions during drying and storage [232]. However, this type of studies was not published for vaginal probiotic microorganisms.…”