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The early detection of microbial contamination is crucial to avoid process failure and costly delays in fermentation industries. However, traditional detection methods such as plate counting and microscopy are labor-intensive, insensitive, and time-consuming. Modern techniques that can detect microbial contamination rapidly and cost-effectively are therefore sought. In the present study, we propose gas chromatography-mass spectrometry (GC-MS)-based metabolic footprint analysis as a rapid and reliable method for the detection of microbial contamination in fermentation processes. Our metabolic footprint analysis detected statistically significant differences in metabolite profiles of axenic and contaminated batch cultures of microalgae as early as 3 h after contamination was introduced, while classical detection methods could detect contamination only after 24 h. The data were analyzed by discriminant function analysis and were validated by leave-one-out cross-validation. We obtained a 97% success rate in correctly classifying samples coming from contaminated or axenic cultures. Therefore, metabolic footprint analysis combined with discriminant function analysis presents a rapid and cost-effective approach to monitor microbial contamination in industrial fermentation processes.

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Protealg ® is the dried and ground whole biomass of Galdieria sulphuraria, a microalga naturally rich in protein and phycocyanin, and contains carotenoids. It is expected that Protealg will be consumed as a food ingredient or supplement by the general public. The safety of Protealg was evaluated in an Ames bacterial reverse mutation test, in vitro mammalian cell micronucleus test, and 13-week oral toxicity study in rats at the dose levels of 500, 2000, and 5000 mg/kg/day. The 13week toxicity study included a 4-week treatment-free period to evaluate recovery. A functional observation battery and ophthalmology examinations were performed, and hematology, blood biochemistry, thyroid hormone, and urinalysis parameters were determined. Seminology parameters and estrus cycle staging were investigated. A macroscopic necropsy examination was performed and tissues were examined microscopically. Protealg showed no evidence of mutagenicity or clastogenic activity. It was well tolerated by rats and no clinical findings indicative of toxicity were observed. There were no significant findings in the in-life or post-mortem investigations. In conclusion, no toxicity was observed after administration of Protealg at dose levels up to 5000 mg/kg/day to rats for 13 weeks, supporting the safety of Protealg for use as a high protein food supplement. The NOAEL was established as 5000 mg/kg/day. Allowing for a margin of exposure of 100-fold, the corresponding anticipated daily intake will be 50 mg/kg/day equivalent to 3.5 g/day for a 70 kg subject. Incorporation levels in various foods will be defined on the basis of appropriate exposure estimations using official recommendations.

The microalgae Galdieria sulphuraria, which belong to the class of cyanidiophyceae, are thermostable at temperatures up to 55°C and have successfully been cultivated under controlled fermentation conditions to produce a protein-rich biomass from which a natural blue proteinaceous pigment, C-phycocyanin can be isolated. The C-phycocyanin has potential use as a colour additive and as a dietary supplement. This C-phycocyanin is resistant to acidic pH down to 2.75, in contrast to the one from Spirulina, which is already used as a colouring agent in agri-food applications. To further promote its use for industrial applications, we report, here, the results of a safety evaluation on a G. sulphuraria extract enriched to 33% C-phycocyanin. This was conducted in a 90-day repeated dose toxicity study in rats at doses from 250 to 4000 mg/kg body weight/day, in bacterial reversal mutation test at doses from 312.5 to 5000 µg/plate and in micronucleus assay at doses from 500 to 2000 µg/mL. Overall, our results indicated that the C-phycocyanin extract from G. sulphuraria did not exert any noteworthy adverse effect of toxicological significance in any of the system used for its safety evaluation, even if some minor changes were observed. According to the 90-day repeated dose toxicity study, no observed adverse effect level of 4000 mg/kg/day could be estimated. In conclusion, this study supports the safety of soluble fraction enriched with C-phycocyanin from G. sulphuraria for its use as food ingredient or supplement.