Dr Selvin S. Solis

Two efficient feather-degrading bacteria were isolated from honeybee samples and identified as Bacillus sonorensis and Bacillus licheniformis based on 16S rRNA and genome sequencing. The strains were able to grow on chicken feathers as the sole carbon and nitrogen sources and degraded the feathers in a few days. The highest keratinase activity was detected by the B. licheniformis CG1 strain (3800 U × mL−1), followed by B. sonorensis AB7 (1450 U × mL−1). Keratinase from B. licheniformis CG1 was shown to be active across a wide range of pH, potentially making this strain advantageous for further industrial applications. All isolates displayed antimicrobial activity against Micrococcus luteus; however, only B. licheniformis CG1 was able to inhibit the growth of Mycobacterium smegmatis. In silico analysis using BAGEL and antiSMASH identified gene clusters associated with the synthesis of non-ribosomal peptide synthetases (NRPS), polyketide synthases (PKSs) and/or ribosomally synthesized and post-translationally modified peptides (RiPPs) in most of the Bacillus isolates. B. licheniformis CG1, the only strain that inhibited the growth of the mycobacterial strain, contained sequences with 100% similarity to lichenysin (also present in the other isolates) and lichenicidin (only present in the CG1 strain). Both compounds have been described to display antimicrobial activity against distinct bacteria. In summary, in this work, we have isolated a strain (B. licheniformis CG1) with promising potential for use in different industrial applications, including animal nutrition, leather processing, detergent formulation and feather degradation.

The gut microbiome plays a critical role in health, disease and immunity. To date, we have access to large datasets describing how the microbial diversity present in the gut correlates with many clinical conditions. However, the microbiome composition is taxonomically complex; influenced by many environmental factors; and variable between individuals and communities, thereby limiting functional and mechanistic insights into the microbiota‒host interactions. We are still unsure of the molecular mechanisms by which gut commensal microbes intrinsically possess to interact with the immune system and induce beneficial responses. This study has addressed this important question by revealing that only certain members of Lactobacillaceae, a bacterial family very well known for its probiotic properties, interact very intimately with macrophages because of their ability to simultaneously overexpress adhesive cell wall proteins and to self-aggregate, leading to significant production of type I interferon (IFN-I) cytokines. IFN-I cytokines are essential to confer protection against viral infections and auto-immune disorders. Specifically, we have proved that this enhanced IFN-I feature is strain-dependent and predominantly driven by cGAS, a molecule that activates the cytosolic sensor STING upon the recognition of bacterial DNA. Furthermore, another cytosolic sensor, NOD2, seems to be an additional stimulus to amplify IFN-I production, suggesting the involvement of successive molecular events for a prominent probiotic response. Our findings provide insight into how specific molecules of probiotic bacteria modulate or stimulate host responses, providing a better understanding of the molecular crosstalk between the microbiome and immune cells.