Connie: Dear friends, welcome to our new podcast, which is happening every Saturday night. Today, it is our pleasure to invite Dr. Leonard Hofstadter, who has been a long-term editor of scientific journals. I believe Dr. Hofstadter will bring a lot of interesting and useful scientific knowledge to our program. Thank you for joining us, Dr. Hofstadter.
Dr. Hofstadter: Thanks, Connie, for inviting me. Good evening, everyone. I have always wanted to participate in this popular science program organized by you, and I’m so thrilled to be here today.
Connie: Wow, I’m flattered. Thanks. So what exciting topic do you have in mind today?
Dr. Hofstadter: I prepared most of the content around probiotics. Hope you and the audience will like it. Let’s first briefly review the origin of the term probiotics. It was first defined in 1965 to describe “a substance secreted by a microorganism that stimulates the growth of another microorganism.” This general claim was later used to define probiotics. Earlier in 1971, the term was used to refer to tissue extracts that stimulated the growth of microorganisms. Later, the term was used to define the living microorganisms or their substances that led to the balance of intestinal microbes. Then in 2001, members of the expert panel of the World Health Organization and the Food and Agriculture Organization of the United Nations defined probiotics as “living microorganisms that give the host health benefits when given in sufficient quantities.” In simple terms, probiotics are referred to as microorganisms or their components that are beneficial to the health of the host. Interestingly, the term “probiotics” is derived from the Greek word, meaning “for life”.
Connie: Do probiotics refer to one kind of bacteria or is it a general term for many kinds of bacteria?
Dr. Hofstadter: In fact, it is a general term for many related bacteria. The most frequently mentioned genus of bacteria belongs to the group of lactic acid bacteria. This flora mainly includes Lactobacillus, Bifidobacterium, Enterococcus, and Streptococcus
Connie: Because probiotics are beneficial to the health of the host, do you know if they have a therapeutic effect on the host suffering from certain diseases?
Dr. Hofstadter: Absolutely. Probiotics have been reported to have a series of therapeutic effects. Such as strengthening the immune defense system, lowering serum cholesterol, preventing colon cancer, gastrointestinal and urinary tract infections, and they can even be used to treat atherosclerosis, arteriosclerosis, rheumatoid arthritis, atopic dermatitis, and many other diseases.
Connie: So these benefits only emerged in recent years?
Dr. Hofstadter: In fact, the use of beneficial microorganisms to improve human health has a long history, which even spans eight or nine centuries. Several reports mention the use of fermented milk to treat gastrointestinal diseases. In India, since the pre-Vedic and Vedic periods, live microorganisms and fermented foods have been used to benefit human health. During the 12th century, fermented milk was consumed by the Mongolian people as a source of health and strength. At the beginning of the twentieth century, Nobel Prize winner Eli Metchnikoff linked the life span of Bulgarians to their high percentage of fermented milk. He even hinted that maybe all microorganisms are not dangerous to human health. The benefits of these microorganisms are thought to be due to their ability to compete with pathogenic microorganisms. Metchnikoff also proposed that autotoxins from putrefactive bacteria in the colon can turn macrophages into phagocytes, and these putrefactive microorganisms can be prevented by replacing them with good bacteria.
Connie: It seems that the effects of probiotics on human health have been the focus lately. I learned that in the past two decades, a large number of research papers on the metabolism and probiotic properties of lactic acid bacteria have appeared in journals. Can we next talk about the types of probiotics?
Dr. Hofstadter: Sure, but before that, we need to know what are the basic characteristics of probiotics.
Connie: Do you mean maintaining the balance of intestinal microbes? I think this is a basic feature of probiotics.
Dr. Hofstadter: You’re right. In other words, the basic feature of probiotics is to provide a “balance” for the growth and biological activity of beneficial gut microflora. At the same time, the unfavorable intestinal microflora is reduced.
Connie: So can we say that the digestive system is the key area where probiotics work?
Dr. Hofstadter: It’s not just the digestive system. Don’t forget about the immune system of the host.
Connie: Is there any challenge in using probiotics to improve the health of the host?
Dr. Hofstadter: The main issue with probiotics is the viability of the strains in different stages of production. The first-generation probiotics only exist in the form of live or freeze-dried bacterial cells without any protection. Therefore, the vigor of these probiotics is low. Then there were the second-generation probiotics, which are freeze-dried probiotics further wrapped to increase their survival rate. However, the release of probiotic strains is a major problem with biological activity.
Connie: Any solution to overcome the problem of the release of probiotics?
Dr. Hofstadter: Yes, that would be the third generation of probiotics. When the microcapsules are destroyed, the encapsulated probiotic strains are released in the metabolically active phase. These probiotics have also been further improved to produce the fourth generation of probiotics. Bacterial cells exist in the form of biofilms, which improves their survival and survivability.
Connie: We know that different kinds of microorganisms are used as probiotics to benefit human health. Remind us of the characteristics of different types of probiotics?
Dr. Hofstadter: Let me introduce them one by one. First, the genus Lactobacillus. Lactic acid bacteria are Gram-positive bacteria and have no spore formation. They are the most common fermenting bacteria, and their main product is lactic acid. According to the difference in metabolic ability, strains can be divided into two types, which are homologous fermentation and heterologous fermentation.
Connie: Where does Lactobacillus exist in the host?
Dr. Hofstadter: They are mainly found in the human digestive tract and urogenital tract. Studies have shown that their existence may fluctuate between species, the age of the host, or the location in the intestine.
Connie: What are some advantages of Lactobacillus in treating diseases?
Dr. Hofstadter: So the lactic acid bacteria used for treatment are considered probiotics, as opposed to antibiotics. In addition, they are considered “friendly” microorganisms. Lactic acid bacteria have potential significance in improving the bioavailability and intake of minerals, reducing the risk of cardiovascular disease, and promoting a balanced metabolism and proper weight.
Connie: Sounds promising.
Dr. Hofstadter: Yes, and the next one in line is bifidobacteria. They belong to the Gram-positive non-spore bacteria of the Bifidobacteriaceae. Bifidobacterium can metabolize glucose to produce lactic acid and acetic acid. This genus is generally found in the human GI tract, the intestines of insects, and birds. They multiply in large numbers during the juvenile period of mammals. They are believed to be related to the characteristics of the immune response and microbial regulators essential to the host intestinal microflora.
Connie: Any other important genus?
Dr. Hofstadter: Of course, don’t forget about Bacillus. Bacillus coagulans belong to the genus Bacillus and is a Gram-positive spore-forming bacteria. Its mechanism of action combines the characteristics of Bacillus and Lactobacillus.
Connie: What are the characteristics of Bacillus coagulans?
Dr. Hofstadter: It can survive high-temperature heat treatment and physiological conditions, such as stomach and bile salts have very low pH values, and directly affect intestinal pathogens. In most cases, this species is also believed to maintain health and treatment by antagonizing pathogens.
Connie: What about the non-pathogenic yeast Saccharomyces boulardii? Is it a kind of probiotics that are beneficial to the health of the host?
Dr. Hofstadter: Certainly. It has attracted worldwide attention. Because they can be used to treat gastrointestinal diseases and other diarrhea diseases caused by the use of antibacterial drugs. In addition, Pseudomonas brucei has many potential probiotic therapeutic properties. It survives in the intestine, its optimum temperature inside and outside is 37 degrees Celsius, and it has antibacterial effects.
Connie: To summarize, Probiotics have great potential in improving human health. Moreover, different kinds of microorganisms are used as probiotics that have beneficial effects on human health. That’s it for our discussion today. Thank you, Dr. Hofstadter, for a very informative and interesting program. And thank you everyone for listening. We will continue our discussion in the next episode. See you then.
Dr. Hofstadter: Thank you. I hope we will see you next time.