California's cattle producers and agricultural communities are all too familiar with the rising challenge of antibiotic resistance, making common bacterial infections harder to treat in livestock. But imagine a future where we could tackle these infections with a natural, powerful alternative. Our research points to just that: antimicrobial peptides (AMPs) found in African catfish.
We're really excited about these peptides because African catfish thrive in pathogen-rich freshwater, naturally producing these robust immune compounds in their skin mucus as a defense. This natural origin makes them highly appealing alternatives to synthetic drugs.
Predicted Safety and Potent Action
One of the most compelling aspects of these AMPs is their predicted safety for mammals. Our initial computer analyses suggest that various catfish AMPs are generally recognized as safe (GRAS). We predict they'll be absorbed in the human intestine without causing liver, brain, or heart toxicity. Furthermore, lab tests on a promising peptide, NACAP-II, confirmed it was non-hemolytic, meaning it didn't damage rabbit red blood cells—a strong indicator of its potential safety for mammalian cells.
Beyond safety, these peptides demonstrate effectiveness against problematic bacteria. One study revealed NACAP-II's strong activity against Extended-Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli—a critical concern for both animal and human health due to its resistance to many common antibiotics. Another peptide, ACAP-IV, also showed antibacterial activity against E. coli and Staphylococcus aureus. We believe these AMPs work by directly disrupting bacterial cell membranes, a mechanism that makes it harder for bacteria to develop resistance compared to how they resist traditional antibiotics.
December 2023: Caring for the Soil
After the fall harvest was over, it was time to clean up and replenish the soil in the Edible Demo Garden. Healthy soil is fundamental to the success of the next season’s crops. Even in beds that are temporarily fallow, the soil needs to be nurtured and protected. In November, volunteers were busy with three major soil-boosting activities - spreading compost, adding mulch, and planting cover crops.
Why add compost?
The value of compost cannot be overestimated. Most edible crops are heavy feeders and leave the soil depleted of nitrogen and other essential nutrients after they are harvested. Adding a layer of compost to the soil is an earth-friendly way to help restore those nutrients and support good soil structure. Since compost is decomposing organic matter, it needs time to make the nutrients available to plants. In the Edible Demo Garden, compost is applied to all the garden beds prior to planting the next season’s crop.
What is the purpose of mulch?
In late fall, Edible Demo Garden volunteers take apart the straw bales used to grow warm season vegetables. The used straw becomes recycled mulch. Initially, the straw was considered suitable as compost material, however, subsequent testing found it to be low in nitrogen. Although much nitrogen was added to the bales during the growing season, most of it was either taken up by the plants or washed out by watering and rain.
Why plant cover crops?
For several years Edible Demo Garden volunteers have been cultivating a large garden area known as “the back 40”. Planting a cover crop of fava beans in the fall is one of the strategies for improving the poor soil in that area. Before the fava beans could be planted in November, some light tilling of the soil was necessary to improve the penetration and decomposition of the four wheelbarrows full of compost spread by the volunteers. Prior to planting, the bean seeds were soaked in an inoculant containing rhizobacteria to maximize their nitrogen fixation effects.
Paying careful attention to spacing and depth requirements, 150 inoculated fava bean seeds were planted in the back 40 by the volunteers. Some watering will be necessary until the rains begin, but a good crop of green manure should be available to nourish the soil in the spring.
For more information on building healthy soil, click here.
