Bioactive peptides (BAPs) obtained from plants and microbes have been thoroughly explored and studied due to their prophylactic properties. The use of BAPs seems to be a promising substitute for several currently available antibiotics because of their antimicrobial properties against foodborne pathogens. BAPs have several other useful properties including antitumor, antihypertensive, antioxidant, antiobesity, and antidiabetic activities. Nowadays, scientists have attempted to recombinantly synthesize bioactive peptides to study their characteristics and potential uses, since BAPs are not found in large quantities in nature. Many pathogenic microorganisms including foodborne pathogens are becoming resistant to various antibiotics. To combat these pathogens, scientists are working to find novel, innovative, and safe antimicrobial agents. Plant‐ and microbe‐based BAPs have demonstrated noteworthy antimicrobial activity against a wide range of pathogenic microorganisms, including foodborne pathogens. BAPs can kill pathogenic microorganisms by disrupting membrane integrity, inhibiting DNA and RNA synthesis, preventing protein synthesis, blocking protein activity, or interacting with certain intracellular targets. In addition, the positive effect of BAP consumption extends to gut microbiota modulation and affects the equilibrium of reactive oxygen species in the gut. This article discusses recombinant BAPs, BAPs generated from plants and microbes, and their antimicrobial applications and modes of action for controlling foodborne pathogens.

COVID-19 vaccination strategies, including heterologous prime–boost regimens and additional booster doses, aim to optimize immune responses. However, seroepidemiological studies on immune responses to different COVID-19 vaccine types and schedules remain limited. This study investigated antibody levels following homologous and heterologous prime-and-boost COVID-19 vaccination in Bangladesh. In a cohort of 606 participants who received first/second/booster doses of vaccines (AstraZeneca, Moderna, Pfizer-BioNTech, and Sinopharm), anti-spike IgG and anti-nucleocapsid IgG levels were measured. Antibody titer variations with respect to age, gender, intervals between doses, and prior infection status were analyzed. mRNA vaccines elicited the highest antibody levels after homologous and heterologous boosting. The AstraZeneca booster resulted in a sharp titer decline rate of ~0.04 units per day. Second or booster vaccine doses significantly increased antibody levels, especially in males (p < 0.05). Older age correlated with higher titers, likely reflecting previous infection, which was further confirmed by the elevation of anti-nucleocapsid IgG levels. About 95.5% of non-Sinopharm recipients were anti-nucleocapsid IgG positive, suggesting prior exposure exceeding self-reported infections (12.5%). mRNA and heterologous COVID-19 boosting enhances humoral immunity over homologous prime–boost vector/inactivated vaccination. However, waning immunity merits further investigation across vaccine platforms.

Bacillus species are widely distributed in nature and are recognized for their capacity to synthesize a wide range of antimicrobial compounds effective against multidrug‐resistant bacterial and fungal pathogens, highlighting their potential as alternatives to conventional antibiotics. This study focused on the isolation of Bacillus spp. from rhizosphere soil capable of producing antimicrobial compounds effective against both gram‐positive and gram‐negative bacteria, and the optimization of different parameters to enhance their production. Of rhizosphere‐soil samples collected from eight different sites in Dhaka city, 96 bacterial isolates were selected to evaluate their antimicrobial activity. Twenty‐seven isolates were preliminarily identified as Bacillus spp. based on their morphological characteristics and biochemical reactions. Five isolates were found to produce inhibitory compounds having antimicrobial properties. The highest antimicrobial compound production was observed at pH 7 and 30°C, rather than at alkaline or acidic pH ( p value = 0.04, < 0.05). Sequence analysis of the 16S rRNA gene of three significant isolates producing antimicrobial compounds revealed that isolates S02b and S03b had 100% sequence similarity to Bacillus safensis , and S04b had 100% similarity with Bacillus pseudomycoides . Whole‐genome sequencing revealed that isolate S02b harbors biosynthetic gene clusters (BGCs) similar to schizokinen (60%), fengycin (53%), bacilysin (85%), bacillibactin (80%), and lichenysin (92%), indicating specialization in peptide‐based secondary metabolite production. It also identified one RiPP and three putative bacteriocin clusters, with area of interest (AOI) 1 matching sactipeptide synthetase (BmbF), amylocyclicin, and UviB, and AOI 2 matching UviB. Thin layer chromatography ( R _f values: 0.45–0.52), the absorbance peak in UV spectra (210–220 nm), and protease sensitivity confirmed the proteinaceous nature of the extracted antimicrobial compounds. The antimicrobial proteinaceous compound (APC) from isolate S02b was nonhemolytic and stable at heat, pH, surfactant, food‐grade metal salt solvent, and organic acid. The scanning electron microscopy image revealed that APCs exhibited significant antimicrobial activity against Staphylococcus aureus , suggesting that APCs could be a promising candidate for new antibiotics.