Safety and efficacy of l-lysine monohydrochloride and concentrated liquid l-lysine (base) produced by fermentation with Corynebacterium glutamicumKCTC 12307BP as feed additives for all animal species

A novel method to derive a human safety limit for PFOA by gene expression profiling and modelling

Perfluorooctanoic acid (PFOA) is a persistent environmental contaminant that can accumulate in the human body due to its long half-life. This substance has been associated with liver, pancreatic, testicular and breast cancers, liver steatosis and endocrine disruption. PFOA is a member of a large group of substances also known as "forever chemicals" and the vast majority of substances of this group lack toxicological data that would enable their effective risk assessment in terms of human health hazards. This study aimed to derive a health-based guidance value for PFOA intake (ng/kg BW/day) from in vitro transcriptomics data. To this end, we developed an in silico workflow comprising five components: (i) sourcing in vitro hepatic transcriptomics concentration-response data; (ii) deriving molecular points of departure using BMDExpress3 and performing pathway analysis using gene set enrichment analysis (GSEA) to identify the most sensitive molecular pathways to PFOA exposure; (iii) estimating freely-dissolved PFOA concentrations in vitro using a mass balance model; (iv) estimating in vivo doses by reverse dosimetry using a PBK model for PFOA as part of a quantitative in vitro to in vivo extrapolation (QIVIVE) algorithm; and (v) calculating a tolerable daily intake (TDI) for PFOA. Fourteen percent of interrogated genes exhibited in vitro concentration-response relationships. GSEA pathway enrichment analysis revealed that "fatty acid metabolism" was the most sensitive pathway to PFOA exposure. In vitro free PFOA concentrations were calculated to be 2.9% of the nominal applied concentrations, and these free concentrations were input into the QIVIVE workflow. Exposure doses for a virtual population of 3,000 individuals were estimated, from which a TDI of 0.15 ng/kg BW/day for PFOA was calculated using the benchmark dose modelling software, PROAST. This TDI is comparable to previously published values of 1.16, 0.69, and 0.86 ng/kg BW/day by the European Food Safety Authority. In conclusion, this study demonstrates the combined utility of an "omics"-derived molecular point of departure and in silico QIVIVE workflow for setting health-based guidance values in anticipation of the acceptance of in vitro concentration-response molecular measurements in chemical risk assessment.

Productivity enhancement in L-lysine fermentation using oxygen-enhanced bioreactor and oxygen vector

Introduction: L-lysine is a bulk product. In industrial production using high-biomass fermentation, the high density of bacteria and the intensity of production require sufficient cellular respiratory metabolism for support. Conventional bioreactors often have difficulty meeting the oxygen supply conditions for this fermentation process, which is not conducive to improving the sugar-amino acid conversion rate. In this study, we designed and developed an oxygen-enhanced bioreactor to address this problem. Methods: This bioreactor optimizes the aeration mix using an internal liquid flow guide and multiple propellers. Results: Compared with a conventional bioreactor, it improved the k_La from 367.57 to 875.64 h^-1, an increase of 238.22%. The results show that the oxygen supply capacity of the oxygen-enhanced bioreactor is better than that of the conventional bioreactor. Its oxygenating effect increased the dissolved oxygen in the middle and late stages of fermentation by an average of 20%. The increased viability of Corynebacterium glutamicum LS260 in the mid to late stages of growth resulted in a yield of 185.3 g/L of L-lysine, 74.57% conversion of lysine from glucose, and productivity of 2.57 g/L/h, an increase of 11.0%, 6.01%, and 8.2%, respectively, over a conventional bioreactor. Oxygen vectors can further improve the production performance of lysine strains by increasing the oxygen uptake capacity of microorganisms. We compared the effects of different oxygen vectors on the production of L-lysine from LS260 fermentation and concluded that n-dodecane was the most suitable. Bacterial growth was smoother under these conditions, with a 2.78% increase in bacterial volume, a 6.53% increase in lysine production, and a 5.83% increase in conversion. The different addition times of the oxygen vectors also affected the final yield and conversion, with the addition of oxygen vectors at 0 h, 8 h, 16 h, and 24 h of fermentation increasing the yield by 6.31%, 12.44%, 9.93%, and 7.39%, respectively, compared to fermentation without the addition of oxygen vectors. The conversion rates increased by 5.83%, 8.73%, 7.13%, and 6.13%, respectively. The best results were achieved by adding oxygen vehicles at the 8th hour of fermentation, with a lysine yield of 208.36 g/L and a conversion rate of 83.3%. In addition, n-dodecane significantly reduced the amount of foam produced during fermentation, which is beneficial for fermentation control and equipment. Conclusion: The new oxygen-enhanced bioreactor improves oxygen transfer efficiency, and oxygen vectors enhance the ability of cells to take up oxygen, which effectively solves the problem of insufficient oxygen supply during lysine fermentation. This study provides a new bioreactor and production solution for lysine fermentation.

Safety and efficacy of a feed additive consisting of l-lysine monohydrochloride and l-lysine sulfate produced by Corynebacterium glutamicum CGMCC 14498 for all animal species (Kempex Holland BV)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of l-lysine monohydrochloride (l-lysine HCl) and l-lysine sulfate produced by Corynebacterium glutamicum (C. glutamicum) CGMCC 14498 as a nutritional feed additive for all animal species. The active substance is l-lysine and it is produced in two different forms (monohydrochloride or sulfate). The production strain C. glutamicum CGMCC 14498 and its recombinant DNA were not detected in the final products. The products l-lysine HCl and l-lysine sulfate do not pose any safety concern associated with the production strain. l-Lysine HCl and l-lysine sulfate produced by C. glutamicum CGMCC 14498 are considered safe for the target species. When using l-lysine sulfate, the background sulfur/sulfate content in the compound feed should be taken into account. l-Lysine HCl and l-lysine sulfate produced by C. glutamicum CGMCC 14498 are safe for the consumer and the environment. In the absence of data, the FEEDAP Panel cannot conclude on the potential of l-lysine HCl produced by the strain C. glutamicum CGMCC 14498 to be toxic by inhalation, and on the potential of l-lysine HCl and l-lysine sulfate produced by the above-mentioned strain to be irritant to skin or eyes, or on their potential to be dermal sensitisers. l-Lysine HCl and l-lysine sulfate produced by C. glutamicum CGMCC 14498 are considered efficacious sources of the essential amino acid l-lysine for non-ruminant animal species. For the supplemental l-lysine to be as efficacious in ruminants as in non-ruminant species, this would require protection against degradation in the rumen.

Safety and efficacy of a feed additive consisting of ferrous lysinate sulfate for all animal species (Phytobiotics Futterzusatzstoffe GmbH)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of ferrous lysinate sulfate as nutritional feed additive for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) Panel was assigned to this mandate. Based on the results of a tolerance study, the FEEDAP Panel concluded that ferrous lysinate sulfate is safe in chickens for fattening when used up to the current maximum authorised levels of total iron in feed; this conclusion was extrapolated to all animal species and categories, at the respective maximum authorised iron levels in complete feed. The use of ferrous lysinate sulfate in animal nutrition up to the maximum iron content in complete feed authorised in the EU poses no concern to the safety of consumers. The FEEDAP Panel concluded that ferrous lysinate sulfate poses a risk to users by inhalation; the additive is not a dermal irritant, but is irritant to eyes and a skin sensitiser. The FEEDAP Panel considered that the use of ferrous lysinate sulfate in animal nutrition would not pose a risk for the environment. Owing to the limitations in the study provided, the FEEDAP Panel could not conclude on the efficacy of the additive for chickens for fattening, and thus, on the efficacy of ferrous lysinate sulfate for all animal species and categories.