## 4 Discussion  
The mechanism of LAB binding mycotoxins is not fully elucidated, and the most prevalent theory is that it is due to physical adsorption between the cell wall of the microorganism and the mycotoxin molecule. The mechanism of adsorption is assumed to be non-covalent, i.e., based on van der Waals, hydrophobic and hydrogen bond interactions [40]. A number of AFB1 binding experiments have been carried out using probiotic LAB, and the results seem to be strain-specific, with the binding efficacy ranging from 0.9 to 100% [41]. Of the LAB species frequently found in fermented plant-based products, _L. plantarum_ showed a statistically significant AFB1 binding capacity in this study. All the strains tested grew to a similar cell density in the 7% fava bean suspension, indicating that the differences in the free AFB1 level determined after cultivation were not a result of the varying cell density during the cultivation procedure. A possible reason for the statistically insignificant AFB1 binding capacity of _P. pentosacous_ could be due to exopolysaccharides or its smaller cell size, which provides less free surface area on its cell wall compared to lactobacilli. As for the tested lactobacillar species, there was a notable difference between _L. plantarum_ and _L. brevis_. On the basis of the cell wall structure, the difference could result from the availability of free surface area on the cell wall. _L. brevis_ has been shown to possess an S-layer, a proteinaceous cell envelope structure. The proteinaceous subunits assemble on the surface of the cell forming a lattice covering the cell wall, which is mainly composed of peptidoglycan [42]. Thus, the S-layer of _L. brevis_ may create a physical barrier, thus hindering the non-covalent adsorption of AFB1 to the cell wall. In previous in vitro studies, heat-inactivated _L. plantarum_ cells have been reported to reduce the level of free AFB1 by 50% during a 5-15 min incubation time [43], and an AFB1 binding rate ranging from 20.88% to 59.44% was achieved with viable and heat-inactivated cells after a 30 min incubation [44]. A longer incubation period of 24 h with viable _L. plantarum_ cells has been reported to increase the AFB1 in vitro removal ratio to 89.5% [45]. In the present study, a similar AFB1 removal ratio was achieved by fermenting a fava bean suspension, which mimics a genuine food processing or preservation process. Similar results were obtained with both _L. plantarum_ strains tested; no strain-specific differences  
Figure 2: Growth of lactic acid bacteria (LAB) in fava bean suspension (FBS) and FBS spiked with 10 mg/kg aflatoxin B1 (AFB1). The columns show an average of three parallel cultivations, and vertical bars represent standard deviation of the mean. With the exception of _L. brevis_ GRL1, the experiments were performed as two independent tests. in the capacity of removing free AFB1 could be detected, even though the studied strains originated from very different ecological niches. Besides being a traditional means to increase the shelf life, nutritional value and sensory properties of food, lactic acid fermentation has gained popularity as a minimal and ecological processing method corresponding with the emerging diet trend favoring sustainability and healthiness. In addition to this, the results of this study suggested that the traditional lactic acid fermentation of proteinaceous plant material by selected LAB starter strains may contribute to the mitigation of risk for background-level AFB1 exposure. Even though fermentation is not capable of replacing the need for antifungal production procedures or mycotoxin controls as the primary means to control mycotoxin risks, it contributes to ensuring health and well-being by mitigating prolonged background-level mycotoxin exposure. In specific agricultural practices such as organic plant production, mycotoxins may pose a notable problem due to the forbidden use of antifungal agrochemicals.