Due to the continuing global concerns involving antibiotic resistance, there is a need for scientific forums to assess advancements in the development of antimicrobials and their alternatives that might reduce development and spread of antibiotic resistance among bacterial pathogens. The objectives of the 2nd International Symposium on Alternatives to Antibiotics were to highlight promising research results and novel technologies that can provide alternatives to antibiotics for use in animal health and production, assess challenges associated with their authorization and commercialization for use, and provide actionable strategies to support their development. The session on microbial-derived products was directed at presenting novel technologies that included exploiting CRISPR-Cas nucleases to produce sequence-specific antimicrobials, probiotics development via fecal microbiome transplants among monogastric production animals such as chickens and mining microbial sources such as bacteria or yeast to identify new antimicrobial compounds. Other research has included continuing development of antimicrobial peptides such as newly discovered bacteriocins as alternatives to antibiotics, use of bacteriophages accompanied by development of unique lytic proteins with specific cell-wall binding domains and novel approaches such as microbial-ecology guided discovery of anti-biofilm compounds discovered in marine environments. The symposium was held at the Headquarters of the World Organisation for Animal Health (OIE) in Paris, France during 12–15 December 2016.

The development of new techniques for the control of pathogenic microorganisms during food production and for the prevention of spoilage are needed to reduce or replace chemical preservatives. This is due to the trend that consumers are increasingly questioning the use of chemical preservatives because of the many health concerns. Because of this issue, bacteriocins and bacteriophages are increasingly viewed as safe natural preservatives with a long history of various applications during food production and preservation. This minireview considers applications of these two antimicrobials, highlights their mode of action, lists their advantages and, when necessary, their limitations. It also reports recent advances in the use of bacteriophages and bacteriocins either alone or in combination in different food matrices. The incentives and effectiveness offered by these antimicrobials in the field of biopreservation are considered for future applications during food production and preservation.

In an attempt to isolate new probiotic bacteria, two Gram-variable, spore-forming, rod-shaped aerobic bacteria designated as strain A4 and A15 were isolated from the feces of Canada geese (Branta canadensis). Strain A4 was able to grow in high salt levels and exhibited lipase activity, while A15 did not propagate under these conditions. Both were positive for starch hydrolysis, and they inhibited the growth of Staphylococcus aureus. The strains of the 16S rRNA sequence shared only 94% similarity to previously identified Sporosarcina spp. The ANI (78.08%) and AAI (82.35%) between the two strains were less than the species threshold. Searches for the most similar genomes using the Mash/Minhash algorithm showed the nearest genome to strain A4 and A15 as Sporosarcina sp. P13 (distance of 21%) and S. newyorkensis (distance of 17%), respectively. Sporosarcina spp. strains A4 and A15 contain urease genes, and a fibronectin-binding protein gene indicates that these bacteria may bind to eukaryotic cells in host gastrointestinal tracts. Phenotypic and phylogenetic data, along with low dDDH, ANI, and AAI values for strains A4 and A15, indicate these bacteria are two novel isolates of the Sporosarcina genus: Sporosarcina sp. A4 sp. nov., type strain as Sporosarcina cascadiensis and Sporosarcina sp. A15 sp. nov., type strain Sporosarcina obsidiansis.

The discovery of novel probiotic bacteria from free-ranging animals for the treatment of inflammatory bowel disease in domestic pets is a unique approach. The chloroform extraction of gastrointestinal (GI) tract material was used to inactivate vegetative cells and select for spore-forming bacteria. A bacterium identified as a novel Paenibacillus sp. strain via small ribosomal RNA (16S) gene sequencing was isolated from the GI tract of a gray wolf (Canis lupus). The bacterium was typed as Gram-variable, both catalase/oxidase-positive and positive via starch hydrolysis and lipase assays. The bacterium inhibited the growth of Staphylococcus aureus, Escherichia coli and Micrococcus luteus. The draft whole genome sequence (WGS) assembly was 7,034,206 bp in length, encoding 6543 genes, and is similar in size and coding capacity to other closely related Paenibacillus spp. The isolate’s genome encodes several germination and sporulation gene products along with antimicrobials such as a bacteriocin system and chitinase. Enzyme genes such as alpha amylase, cellulase, lipases and pectin lyase are also present in the genome. An incomplete lysogenic bacteriophage genome was also present in the isolate’s genome. Phenotypic characteristics combined with a WGS genotype analysis indicate that this bacterium, designated Paenibacillus sp. ClWae2A, could be a potential candidate probiotic for domestic dogs.

Campylobacter is a major cause of acute human diarrheal illness. Broiler chickens constitute a primary reservoir for C. jejuni leading to human infection. Consequently, there is a need for developing novel intervention methods. Antimicrobial peptides (AMP) are small proteins which have evolved in most lifeforms to provide defense against microbial infections. To date, over 3000 AMP have been discovered; however, few of them have been analyzed specifically for ability to kill campylobacters. We selected and evaluated a set of 11 unique chemically synthesized AMP for ability to inhibit growth of C. jejuni. Six of the AMP we tested produced zones of inhibition on lawns of C. jejuni. These AMP included: NRC-13, RL-37, Temporin L, Cecropin–Magainin, Dermaseptin, and C₁₂K-2β₁₂. In addition, MIC were determined for Cecropin–Magainin, RL-37 and C₁₂K-2β₁₂ against 15 isolates of Campylobacter representing the three most common pathogenic strains. MIC for campylobacters were approximately 3.1 µg/mL for AMP RL-37 and C₁₂K-2β₁₂. MIC were slightly higher for the Cecropin–Magainin AMP in the range of 12.5 to 100 µg/mL. These AMP are attractive subjects for future study and potential in vivo delivery to poultry to reduce Campylobacter spp. populations.