Nonviable antibiotic-resistance-free bioactive postbiotics derived from viable probiotic lactobacillus spp. : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Manawatu, New Zealand. EMBARGOED until 14th January 2028

Abstract

With reports that viable cells of probiotic lactic acid bacteria (LAB) are unsafe when consumed by or administered to selected human beings, postbiotics comprising nonviable LAB cells and the products secreted by them are considered an option to avoid such risks, especially potential transmission of antibiotic resistance genes to other microbes. In this review, the functionality and safety of nonviable postbiotics relative to viable LAB Lactobacillus spp. were examined by collecting the relevant literature from databases and publications. The study indicated that, even after inactivation, postbiotics of Lactobacillus spp. remain active in the gastrointestinal tract with probiotic bioactivities such as antimicrobial action, barrier function, microbiota balance, immune-regulating and anti-inflammatory responses. As they lack cell viability devoid of resistance to antibiotics, postbiotics of Lactobacillus spp. are relatively risk-free but endowed with uncompromised activities and health benefits suitable for varied uses in food science and therapeutics, enlarging the scope for both progenitor probiotics and postbiotics derived from them. Safety-wise, compared to resistance-prone high-risk antibiotics, live probiotics are at low-risk shadowed by antibiotic resistance, while inanimate postbiotics are risk-free without the viability-linked antibiotic resistance.