The research, framed within the national Olivebiome project, seeks to transform horticultural by-products into functional ingredients to improve animal intestinal health and reduce the use of antibiotics in livestock farming.
The Andalusian Biotechnology Foundation (FABT) has presented its first progress report following its incorporation into the national Olivebiome project, an initiative financed with European funds that pursues a key biotechnological transformation: converting plant waste such as olive pomace and other horticultural by-products into functional ingredients for animal feed.
Although the trials are still underway and the report is preliminary, the work carried out after the Andalusian Foundation joined the project between March and April 2025 has laid the groundwork for selecting and modeling the best combinations of fibers and probiotic strains. The goal is clear: to offer a natural and sustainable alternative to the use of antibiotics in poultry and pig farming.
Microbial cultures in plant by-products
The first line of research has focused on evaluating the prebiotic activity of olive grove by-products. The raw materials tested, rich in fiber and of plant origin, were subjected to milling processes to homogenize their texture and facilitate subsequent microbial bioprocesses.
However, the complexity of these plant matrices necessitated a rethinking of the initial methodology. Instead of using spectrophotometry on microtiter plates, microbial growth assays were performed in Erlenmeyer flasks and Falcon tubes, formats more suitable given the physical characteristics of the samples.
One of the most significant technical challenges was the high initial microbial load of the raw materials, which hindered the selective growth of the probiotic strains under study. To avoid interference, a sanitizing heat treatment was applied at 90°C for 20 minutes. Although this step proved helpful, it was not sufficient to completely eliminate microbial contamination, ultimately leading to the use of an autoclave as the standardized process.
Preparation and analysis of probiotic cultures
Once the culture conditions were stabilized, inocula of four probiotic strains were prepared: two commercial strains (Lactobacillus rhamnosus and casei) and two candidate strains provided by the foundation itself (Lactococcus lactis and Wessiella cibaria). All strains were cultured in MRS Broth medium at 37°C for 24 hours, yielding pure cultures that were adjusted to a concentration of 10⁸ CFU/ml.
Through spectrophotometry, the absorption maxima of each culture were determined, establishing the optimal wavelength for subsequent readings (625 nm). This allowed for the design of more precise growth kinetics for each combination of plant fiber and probiotic.
In addition, all plant samples and reference prebiotics (inulin and FOS) were coded with a specific nomenclature, which facilitated the organization of the test batches.
Experimental design of the batches
The experimental work was structured in three large batches:
- Batch1: Combinations of vegetable fibers with saline solution and different bacterial strains.
- Batch 2: MRS Broth media as controls to verify the growth of the strains under ideal conditions.
- Batch 3: Combination of vegetable fibers with MRS Broth medium and bacteria to compare fermentative behavior.
All tubes were pre-autoclaved and adjusted to a neutral pH (7.0) before inoculation. They were then incubated at 39°C and readings were taken at 0, 6, 24, 48, and 72-hour intervals. The objective was to determine three key parameters in each assay: maximum growth rate (µmax), lag phase (lag), and maximum growth (Nmax).
Currently, this data is being analyzed, and additional replications are planned to validate the results and apply statistical treatment.
Fermentations are underway to select the best fibers
In parallel with the previous activity, a second line of research has been initiated, focused on identifying the three best raw materials with a prebiotic profile for future pilot-scale fermentation. This phase is still underway, but the initial results already suggest significant differences in the fermentative capacity of the various fibers.
The work of the Andalusian Biotechnology Foundation (FABT) is being carried out within the framework of the Olivebiome research project, which is led technically by the Cantabrian company Maslina, specializing in natural extracts from plant byproducts. The project also includes the participation of other leading organizations such as Lucta S.A. and San Miguel Arcángel S.A., and subcontracted members include AINIA, IRTA, Microomics Systems, and FABT itself, among others.