Citation: Ziarno, M.; Zar˛ eba, D.; ´ Scibisz, I.; Kozlowska, M. Exploring the Cholesterol-Modifying Abilities of Lactobacilli Cells in Digestive Models and Dairy Products. Microorganisms 2023, 11, 1478. https://doi.org/10.3390/ microorganisms11061478 Academic Editor: Piotr B. Heczko Received: 9 May 2023 Revised: 27 May 2023 Accepted: 30 May 2023 Published: 1 June 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). microorganisms Article Exploring the Cholesterol-Modifying Abilities of Lactobacilli Cells in Digestive Models and Dairy Products Malgorzata Ziarno 1, * , Dorota Zar ˛ eba 2 , Iwona ´ Scibisz 1 and Mariola Kozlowska 3 1 Department of Food Technology and Assessment, Institute of Food Science, Warsaw University of Life Sciences—SGGW (WULS-SGGW), Nowoursynowska 159c St., 02-776 Warsaw, Poland; iwona_scibisz@sggw.edu.pl 2 Professor E. Pijanowski Catering School Complex in Warsaw, 04-110 Warsaw, Poland; dorotazareba@gmail.com 3 Department of Chemistry, Institute of Food Science, Warsaw University of Life Sciences—SGGW (WULS-SGGW), Nowoursynowska 159c St., 02-776 Warsaw, Poland; mariola_kozlowska@sggw.edu.pl * Correspondence: malgorzata_ziarno@sggw.edu.pl; Tel.: +48-225-937-666 Abstract: This study aimed to investigate the ability of lactic acid bacteria to remove cholesterol in simulated gastric and intestinal fluids. The findings showed that the amount of cholesterol removed was dependent on the biomass, viability, and bacterial strain. Some cholesterol binding was stable and not released during gastrointestinal transit. The presence of cholesterol affected the fatty acid profile of bacterial cells, potentially influencing their metabolism and functioning. However, adding cholesterol did not significantly impact the survival of lactic acid bacteria during gastrointestinal transit. Storage time, passage, and bacterial culture type did not show significant effects on cholesterol content in fermented dairy products. Variations in cell survival were observed among lactic acid bacteria strains in simulated gastric and intestinal fluids, depending on the environment. Higher milk protein content was found to be more protective for bacterial cells during gastrointestinal transit than fat content. Future research should aim to better understand the impact of cholesterol on lactic acid bacteria metabolism and identify potential health benefits. Keywords: lactic acid bacteria; gastric juice; intestinal juice; gastrointestinal transit; fatty acid profile; cell survival; health benefits 1. Introduction Changes in lifestyle and diet, as well as the development of civilization, have con- tributed to an increase in so-called “civilization diseases,” also referred to as chronic noncommunicable diseases. Ischemic heart disease, which is also known as coronary artery disease, is an example of a lifestyle disease, with the main cause being the arteriosclerosis of the coronary arteries, leading to their narrowing. Hypercholesterolemia, or elevated LDL cholesterol levels, is one of the risk factors for atherosclerosis. Elevated cholesterol has been identified as a crucial cardiovascular disease risk factor, and even a small reduc- tion in cholesterol levels can reduce the risk of coronary artery disease [1–5]. Cholesterol and oxysterols (the result of cholesterol oxidation) play a significant role in the process of atherosclerotic plaque formation [5]. Atherosclerotic plaques, primarily composed of cholesterol and other substances, are the main cause of narrowing blood vessels and the development of blood clots, which can lead to serious cardiovascular complications such as heart attack and stroke. Oxysterols have the ability to induce inflammation in the blood vessel walls and promote lipid oxidation, contributing to the development and progression of atherosclerosis [5]. Studies have shown that consuming fermented milk products, such as yogurt, can lower cholesterol levels in humans [6,7]. As early as 1974, Mann and Spoerry [8,9] Microorganisms 2023, 11, 1478. https://doi.org/10.3390/microorganisms11061478 https://www.mdpi.com/journal/microorganisms