## 1 Introduction  
Eating habits and lifestyles can cause various diseases such as cancers, diabetes, and mental illness. Furthermore, the incidence of chronic diseases has been increasing [1]. Many types of cancers exist, and some cancers are susceptible to metastasis. For the treatment of cancers, chemotherapy and surgical cure are generally performed. However, anticancer drugs and surgical removal have side effects and risks of recurrence. To reduce the risk of recurrence, many studies have been conducted to develop treatments. In particular, the incidence of colorectal cancer is so high that it ranks first among many countries; in Korea (12.5%), it is the third most common cancer after thyroid and stomach cancer. Representative causes include family history, inflammatory bowel disease, excessive fat intake, insufficient dietary fiber intake, and lifestyles such as smoking and drinking, and obesity. Representative treatments include radical resection, chemotherapy, and radiation therapy. However, 20-50% of patients recur within four years after surgery [2, 3]. For this reason, it is necessary to develop effective anticancer drugs with low side effects and risks, and the development of functional foods and pharmaceuticals through the search for physiologically active substances has been actively studied and conducted.  
There are many microorganisms in the gut of humans, animals, and insects. The intestinal environment is most stable when harmful and beneficial bacteria are in equilibrium, and when beneficial bacteria are reduced, diseases such as allergy and diarrhea are the result. In the case of human intestinal flora, the intestinal environment can be improvedthrough the effects of ingested food [4]. Living microorganisms that have beneficial effects on health by improving the ability of the host's intestinal flora are designated as 'probiotics'. Lactic acid bacteria (LAB) such as _Lactobacillus, Bifidobacterium, Lactococcus, Leuconstoc, Bacillus_, and _Propionibacterium_ are widely used for the preparation of probiotics [5]. Probiotics can survive under appropriate intestinal conditions (acidic pH, enzymes, biliary salts, etc.). To affect the human body, sufficient amounts of probiotics must reach the gut [6]. In recent studies on probiotics, tumor-suppressing activity was confirmed in the preparation of _Bifidobacterium bifidum_ BGN4 [7]. In addition, several other studies have identified the physiologically active function in the fractions obtained from various probiotics. Cell-free extracts or cell metabolites have a beneficial effect similar to live probiotics, and are named as bacteria 'paraprobiotics' or 'postbiotics' [8]. Postbiotics are referred to as 'non-viable inactivated probiotics', or 'ghost probiotics'. Studies on the safety of postbiotics have been conducted in various ways, and a study of 1740 children reported that there were no side effects when postbiotics were administered, but rather showed a therapeutic effect on irritable bowel disease [9]. Postbiotics were prepared by various methods including ultrasonication, heat-killed, freeze-drying, ohmic heating, supercritical CO\({}_{2}\), pulsed electric field, and irradiation methods [10].  
Postbiotics are in the spotlight as next-generation probiotics. However, in comparison with probiotics, the research on their manufacturing methods and investigation of their functional aspects are still insufficient. In this study, postbiotic substances were extracted in various ways from lactic acid bacteria with antioxidant activity isolated from kimchi and newborn infant feces [11], and their anti-proliferation effect against HT-29 cells was investigated.