In vitro interactions of Alternaria mycotoxins, an emerging class of food contaminants, with the gut microbiota: a bidirectional relationship

Abstract

The human gut microbiota plays an important role in the maintenance of human health. Factors able to modify its composition might predispose the host to the development of pathologies. Among the various xenobiotics introduced through the diet, Alternaria mycotoxins are speculated to represent a threat for human health. However, limited data are currently available about the bidirectional relation between gut microbiota and Alternaria mycotoxins. In the present work, we investigated the in vitro effects of different concentrations of a complex extract of Alternaria mycotoxins (CE; containing eleven mycotoxins; e.g. 0.153 µM alternariol and 2.3 µM altersetin, at the maximum CE concentration tested) on human gut bacterial strains, as well as the ability of the latter to metabolize or adsorb these compounds. Results from the minimum inhibitory concentration assay showed the scarce ability of CE to inhibit the growth of the tested strains. However, the growth kinetics of most of the strains were negatively affected by exposure to the various CE concentrations, mainly at the highest dose (50 µg/mL). The CE was also found to antagonize the formation of biofilms, already at concentrations of 0.5 µg/mL. LC–MS/MS data analysis of the mycotoxin concentrations found in bacterial pellets and supernatants after 24 h incubation showed the ability of bacterial strains to adsorb some Alternaria mycotoxins, especially the key toxins alternariol, alternariol monomethyl ether, and altersetin. The tendency of these mycotoxins to accumulate within bacterial pellets, especially in those of Gram-negative strains, was found to be directly related to their lipophilicity.

Alternaria toxins—Still emerging?

“…Since caveolin regulates fatty acids uptake (Pohl et al., 2002) and membrane proteins turnover (Shi & Sottile, 2008; Urra et al., 2012), this implies possible changes on transmembrane receptors distribution or uptake and confirms previous studies reporting the interaction between AOH and the GM1 plasma membrane raft ganglioside in RAW 264.7 macrophages (Solhaug et al., 2013). In addition, it was recently described how structure and biophysical properties (e.g., lipophilicity) of Alternaria mycotoxins seem to drive accumulation into microbial pellets, possibly via interaction with bacterial walls (Crudo et al., 2021). If this interpretation would be confirmed, the interaction mycotoxins‐membranes could substantially affect toxins’ bioavailability and biodistribution after oral intake.…”

“…A recently published follow‐up study described Alternaria toxins to selectively impact the viability and growth of bacterial strains that colonize the gut, shedding light on the bidirectional interaction of the gut microbiome with mycotoxins (Crudo et al., 2021). Intriguingly, low concentrations (0.5 μg/ml) of the applied extract from an Alternaria alternata culture were shown to significantly inhibit biofilm formation by various microbes, including Bacteroides caccae , Bacteroides thetaiotaomicron , Bacteroides vulgatus and Escherichia coli .…”

Autochthonous fungi are central components in microbial community structure in raw fermented sausages

“…Alternaria spp. produce mycotoxins that have been found to affect the growth of human gut bacterial strains, impairing a healthy gut microbial community (Crudo et al ., 2021 ). In addition, Alternaria alternata produces a range of potent allergenic proteins that can induce or enhance respiratory allergic diseases (Gabriel et al ., 2016 ).…”

Kelimpahan Fungi Kelas Dothideomycetes Pada Lumba-lumba Hidung Botol (Tursiops aduncus)

“…Alternaria merupakan salah satu genus fungi mikotoksigenik utama dengan lebih dari 70 metabolit yang dilaporkan dapat menyebabkan mutagenisitas, karsinogenisitas, induksi pemutusan untai DNA, gangguan metabolisme sphingolipid, atau penghambatan aktivitas enzim dan fotofosforilasi (Escrivá et al, 2017). Studi In vitro dengan menggunakan sebelas mikotoksin Alternaria (misalnya 0,153 M alternariol dan 2,3 M altersetin) dapat mempengaruhi pertumbuhan strain bakteri usus (Crudo et al, 2021). Alternaria juga di laporkan berperan sebagai biokontrol pada tanaman (Babu et al, 2002).…”