As with heterotrophic biofuel production, product toxicity is likely a limiting factor.
However, in the case of most biofuel production processes, the end product toxicity has been identified as a major problem [ 14].
Those with the most significant effect on the production of toxicity are summarized in table 2. Heat shock (70°C) was necessary to obtain toxicity whereas 100°C or 0.22 µm filtration treatments prevented it.
However, the safe application of this process, termed as nanoselection or nanopurification in previous studies, in food animal production and toxicity concerns has yet to be explored.
Furthermore, unlike immortalized cells on plastic, these 3-D organoid kidney cultures provide a more physiologically-relevant response to nephrotoxic agent exposure, with production of toxicity biomarkers found in vivo.
Three key challenges include high cellulase production cost, toxicity of the cellulosic hydrolysate to microbial strains, and poor ability of fermenting microorganisms to utilize certain fermentable sugars in the hydrolysate.
In particular, disturbances in both the intracellular compartmentalization of copper as well as in its extracellularly released forms may contribute to Aβ production and toxicity [16].
The greater availability of superoxide may favor peroxynitrite production and toxicity.
Recent studies have suggested that the wingless cysteine-rich glycosylated protein Wnt1 [ 36- 38] may limit the production and toxicity of Aβ[ 39, 40].
Despite these successes in microbial alkane production, the toxicity of alkanes to microbial hosts can eventually be a bottleneck for high productivity.
