The transcriptome of Listeria monocytogenes during co-cultivation with cheese rind bacteria suggests adaptation by induction of ethanolamine and 1,2-propanediol catabolism pathway genes

Abstract

The survival of Listeria (L.) monocytogenes in foods and food production environments (FPE) is dependent on several genes that increase tolerance to stressors; this includes competing with intrinsic bacteria. We aimed to uncover genes that are differentially expressed (DE) in L. monocytogenes sequence type (ST) 121 strain 6179 when co-cultured with cheese rind bacteria. L. monocytogenes was cultivated in broth or on plates with either a Psychrobacter or Brevibacterium isolate from cheese rinds. RNA was extracted from cocultures in broth after two or 12 hours and from plates after 24 and 72 hours. Broth co-cultivations with Brevibacterium or Psychrobacter yielded up to 392 and 601 DE genes, while plate co-cultivations significantly affected the expression of up to 190 and 485 L. monocytogenes genes, respectively. Notably, the transcription of virulence genes encoding the Listeria adhesion protein and Listeriolysin O were induced during plate and broth cocultivations. The expression of several systems under the control of the global stress gene regulator, σ B , increased during co-cultivation. A cobalamin-dependent gene cluster, responsible for the catabolism of ethanolamine and 1,2-propanediol, was upregulated in both broth and plate co-cultures conditions. Finally, a small non-coding (nc)RNA, Rli47, was induced after 72 hours of co-cultivation on plates and accounted for 50-90% of the total reads mapped to L. monocytogenes. A recent study has shown that Rli47 may contribute to L. monocytogenes stress survival by slowing growth during stress conditions through the suppression of branch-chained amino acid biosynthesis. We hypothesize that Rli47 may have an impactful role in the response of L. monocytogenes to co-cultivation by regulating a complex network of metabolic and virulence mechanisms.

The Cobalamin-Dependent Gene Cluster of Listeria monocytogenes: Implications for Virulence, Stress Response, and Food Safety

“…We also observed that Rli47 was by far the most expressed gene during co-cultivation, further linking the functions of Rli47 and the CDGC (Anast and Schmitz-Esser, 2020). The authors of some recent studies (Tang et al, 2015;Tirumalai, 2015;Anast and Schmitz-Esser, 2020) concur that L. monocytogenes is most likely searching for alternative nutrients to fit into competitive niches, perhaps in a more cooperative approach.…”

“…L. monocytogenes also increased expression of the pdu gene cluster in co-culture biofilm with Bacillus subtilis but not in mono-culture biofilm (Tirumalai, 2015). Recently, a study from our laboratory that co-cultured L. monocytogenes with either a Brevibacterium or Psychrobacter food isolate found that the CDGC was highly upregulated in a modular way and was dependent on co-culture condition (Anast and Schmitz-Esser, 2020). We also observed that Rli47 was by far the most expressed gene during co-cultivation, further linking the functions of Rli47 and the CDGC (Anast and Schmitz-Esser, 2020).…”

“…Several L. monocytogenes pdu and cob genes are regulated on a global scale directly by the stress regulator σ B (Liu et al, 2017), and are directly or indirectly influenced by the non-coding RNA, Rli47 (Marinho et al, 2019). Rli47 has recently emerged as an important regulatory element in virulence and especially during stress response (Toledo-Arana et al, 2009;Archambaud et al, 2012;Mujahid et al, 2012;Marinho et al, 2019;Anast and Schmitz-Esser, 2020;Cortes et al, 2020).…”

“…Although it is well established that the CDGC may contribute to the survival of foodborne pathogens in food and food production environments (Chan et al, 2008;Fox et al, 2011;Srikumar and Fuchs, 2011;Goudeau et al, 2013;Tang et al, 2015;Kaval and Garsin, 2018;Anast and Schmitz-Esser, 2020), functional characterizations of the L. monocytogenes CDGC importance during food and food production associated stresses are far more limited than studies that assess its contribution to virulence. PD and EA are found in many food products as constituents of glycoconjugates or lipids and are used as additives of various food products and containers (Cameron et al, 1998;Tang et al, 2015).…”

“…Recently, a study from our laboratory that co-cultured L. monocytogenes with either a Brevibacterium or Psychrobacter food isolate found that the CDGC was highly upregulated in a modular way and was dependent on co-culture condition (Anast and Schmitz-Esser, 2020). We also observed that Rli47 was by far the most expressed gene during co-cultivation, further linking the functions of Rli47 and the CDGC (Anast and Schmitz-Esser, 2020). The authors of some recent studies (Tang et al, 2015;Tirumalai, 2015;Anast and Schmitz-Esser, 2020) concur that L. monocytogenes is most likely searching for alternative nutrients to fit into competitive niches, perhaps in a more cooperative approach.…”