During the last few decades, the main focus of numerous studies has been on the human breast milk microbiota and its influence on the infant intestinal microbiota and overall health. The presence of lactic acid bacteria in breast milk affects both the quantitative and qualitative composition of the infant gut microbiota. The aim of this study was to assess the most frequently detected cultivable rod-shaped lactobacilli, specific for breast milk of healthy Bulgarian women and fecal samples of their infants over the first month of life, in 14 mother–infant tandem pairs. Additionally, we evaluated the strain diversity among the most common isolated species. A total of 68 Gram-positive and catalase-negative strains were subjected to identification using the MALDI-TOF technique. Predominant cultivable populations belonging to the rod-shaped lactic acid bacteria have been identified as Lacticaseibacillus rhamnosus, Limosilactobacillus fermentum, Lacticaseibacillus paracasei, and Limosilactobacillus reuteri. Also, we confirmed the presence of Lactiplantibacillus plantarum and Lactobacillus gasseri. Up to 26 isolates were selected as representatives and analyzed by 16S rRNA sequencing for strain identity confirmation and a phylogenetic tree based on 16S rRNA gene sequence was constructed. Comparative analysis by four RAPD primers revealed genetic differences between newly isolated predominant L. rhamnosus strains. This pilot study provides data for the current first report concerning the investigation of the characteristic cultivable lactobacilli isolated from human breast milk and infant feces in Bulgaria.

During the last few decades, the main focus of numerus studies has been on the human breast milk microbiota and its influence on the infant intestinal microbiota and overall health. The presence of lactic acid bacteria in breast milk affects both the quantitative and qualitative composition of the infant gut microbiota. The aim of this study was to assess the dominant cultivable rod-shaped lactic acid bacteria, specific for breast milk of healthy Bulgarian women and fecal samples of their infants over the first month of life, in 14 mother-infant tandem pairs. Additionally, we evaluated strain diversity among the dominant newly isolated species. 68 gram-positive and catalase negative strains were subjected to identification by using MALDI-TOF technique. Predominant culturable populations belonging to the rod-shaped lactic acid bacteria have been identified as Lacticaseibacillus rhamnosus, Limosilactobacillus fermentum, Lacticaseibacillus paracasei and Limosilactobacillus reuteri. Also, we confirmed the presence of Lactiplantibacillus plantarum and Lactobacillus gasseri. 27 isolates were selected as representatives and analyzed by 16S rDNA sequencing for strain identity confirmation and a phylogenetic tree based on 16S rDNA gene sequence was constructed. Comparative analysis by four RAPD primers revealed genetic differences between newly isolated L. rhamnosus strains. This pilot study provides data for the current first report concerning investigation on characteristic microbiota of human breast milk and infant feces in Bulgaria.

Foodborne diseases remain a major global public health concern. According to the World Health Organization (WHO), contaminated food causes nearly 500,000 deaths annually. Consequently, the development of novel strategies to control foodborne pathogens and prevent microorganism-induced plant diseases remains an important research priority, attracting considerable scientific attention worldwide. This study describes the design and synthesis of novel dihydropyrazolines containing an ethylpiperazine moiety as potential antimicrobial agents. The antibacterial activity of the newly synthesized heterocyclic compounds, along with their corresponding chalcone precursors, was evaluated against Gram-positive and Gram-negative foodborne pathogens and phytopathogenic bacteria. The assessment was performed using a two-step protocol comprising an initial qualitative screening of selected bacterial species, followed by a quantitative evaluation of the inhibitory effects of individual compounds and their combinations. Among the tested compounds, pyrazolines 4a and 4b and chalcone 3b exhibited notable strain-dependent antibacterial activity, particularly against phytopathogenic strains of Pseudomonas syringae, while compound 4a demonstrated the highest efficacy against the Gram-negative foodborne pathogens Escherichia coli, Salmonella enterica and Listeria monocytogenes. Thus, the potential of the N-ethylpiperazine moiety as a key structural feature contributing to the antimicrobial activity of the studied compounds is revealed.