In this study, a wide pool of lactic acid bacteria strains deposited in two recognized culture collections was tested against ropy bread spoilage bacteria, specifically belonging to Bacillus spp., Paenibacillus spp., and Lysinibacillus spp. High-throughput and ex vivo screening assays were performed to select the best candidates. They were further investigated to detect the production of active antimicrobial metabolites and bacteriocins. Moreover, technological and safety features were assessed to value their suitability as biocontrol agents for the production of clean-label bakery products. The most prominent inhibitory activities were shown by four strains of Lactiplantibacillus plantarum (NFICC19, NFICC 72, NFICC163, and NFICC 293), two strains of Pediococcus pentosaceus (NFICC10 and NFICC341), and Leuconostoc citreum NFICC28. Moreover, the whole genome sequencing of the selected LAB strains and the in silico analysis showed that some of the strains contain operons for bacteriocins; however, no significant evidence was observed phenotypically.

This study investigated the development of amino acids and peptides derived from brewer’s spent grains (BSG) of wheat and stout beers under 10-day fermentation using Lactiplantibacillus plantarum. Fermented wheat beer’s BSG contained a higher number of peptides compared to fermented stout beer’s BSG, with 1,227 versus 436 peptides identified, respectively. Specifically, fermented wheat beer’s BSG exhibited an increase in peptide numbers in day 4, whereas fermented stout beer’s BSG showed an increase in peptide numbers in days 8 and 9. Most peptides identified in fermented BSGs were linked to predicted antihypertensive, antimicrobial, and antibacterial properties, while others, derived from wheat, contained intact celiac disease epitopes. Moreover, after 10-day fermentation, free hydrophobic amino acids in fermented stout beer’s BSG (0.98 mg/100g BSG protein) were 60% higher than hydrophilic amino acids (0.61 mg/100g BSG protein), indicating the enzymes in Lb. plantarum could favour the release of hydrophobic amino acids.

Brewer’s spent grain (BSG), the major by-product of the brewing industry, has attracted growing interest in valorisation through lactic acid bacteria fermentation. However, research has largely focused on Lactiplantibacillus plantarum, while other species have mainly been investigated using enzymatic hydrolysates rather than intact solid BSG. This study compared the solid-state fermentation performance of Lacticaseibacillus rhamnosus ATCC 7469 and Limosilactobacillus fermentum ATCC 9338 on BSG over 10 days. In vitro antioxidant, antidiabetic, anti-obesity, and antimicrobial activities were assessed every two days and integrated into a global bioactivity score. Lacticaseibacillus rhamnosus successfully colonised the substrate, reaching 9.62 log₁₀ CFU g⁻¹ on Day 2 and reducing the pH to 3.6. Antioxidant capacity peaked on Day 2, whereas antidiabetic and anti-obesity activities peaked on Day 10. Bactericidal activity was also confirmed in a bread-simulating matrix, and the global bioactivity score identified Day 2 as the highest-scoring endpoint. In contrast, Limosilactobacillus fermentum failed to establish a successful fermentation, with polymicrobial contamination observed from Day 4 onwards. To investigate whether substrate sterilisation could improve Limosilactobacillus fermentum fermentation performance, autoclaving and a two-step heat treatment were evaluated. Although autoclaving effectively sterilised the substrate, it reduced the number of detectable proteins by nearly 25%, whereas the two-step heat treatment preserved the protein profile but did not support successful fermentation by Limosilactobacillus fermentum. Overall, these findings identify Lacticaseibacillus rhamnosus as a promising candidate for BSG valorisation and underscore the importance of strain selection, as fermentation performance can vary substantially among lactic acid bacteria.