Complete Circular Genome Sequence and Temperature Independent Adaptation to Anaerobiosis of Listeria weihenstephanensis DSM 24698.

Elena Ferrari,Christopher Huptas,Siegfried Scherer,Mathias C Walter,Stefanie Müller-Herbst

doi:10.3389/fmicb.2017.01672

Abstract

The aim of this study was to analyze the adaptation of the environmental Listeria weihenstephanensis DSM 24698 to anaerobiosis. The complete circular genome sequence of this species is reported and the adaptation of L. weihenstephanensis DSM 24698 to oxygen availability was investigated by global transcriptional analyses via RNAseq at 18 and 34°C. A list of operons was created based on the transcriptional data. Forty-two genes were upregulated anaerobically and 62 genes were downregulated anaerobically. The oxygen dependent gene expression of selected genes was further validated via qPCR. Many of the differentially regulated genes encode metabolic enzymes indicating broad metabolic adaptations with respect to oxygen availability. Genes showing the strongest oxygen-dependent adaption encoded nitrate (narGHJI) and nitrite (nirBD) reductases. Together with the observation that nitrate supported anaerobic growth, these data indicate that L. weihenstephanensis DSM 24698 performs anaerobic nitrate respiration. The wide overlap between the oxygen-dependent transcriptional regulation at 18 and 34°C suggest that temperature does not play a key role in the oxygen-dependent transcriptional regulation of L. weihenstephanensis DSM 24698.

Highlights

Listeria are Gram-positive, facultative anaerobic, non-spore-forming, rod-shaped bacteria, 0.5 μm in width and 1.0–1.5 μm in length, with a low G+C content (McLauchlin and Rees, 2009), which can be isolated from a variety of environments, including soil, water, wastewater, sludge, feces, silage, food, and food processing environments (Paillard et al, 2005; Vilar et al, 2007; O’Connor et al, 2010; Linke et al, 2014)
Blast analysis revealed that the protein sequence of the phage DNA polymerase (UE_5225) and a putative phage tail tape measure protein (UE_5365) matched with proteins encoded in the genome of L. monocytogenes and L. ivanovii strains with a 79–82% and 79–81% identity, indicating its putative relationship to other Listeria phages
The genes narGHJI and nirBD showed the strongest transcriptional induction during anaerobic growth, leading to the hypothesis that under anaerobic growth conditions L. weihenstephanensis DSM 24698 might switch from aerobic respiration to nitrate respiration

Summary

Introduction

Listeria are Gram-positive, facultative anaerobic, non-spore-forming, rod-shaped bacteria, 0.5 μm in width and 1.0–1.5 μm in length, with a low G+C content (McLauchlin and Rees, 2009), which can be isolated from a variety of environments, including soil, water, wastewater, sludge, feces, silage, food, and food processing environments (Paillard et al, 2005; Vilar et al, 2007; O’Connor et al, 2010; Linke et al, 2014). The genus Listeria currently contains 17 species which are, based on comparative genomics, divided in the Listeria sensu stricto and the Listeria sensu lato group (Chiara et al, 2015). The Listeria sensu stricto clade includes Listeria monocytogenes (Pirie, 1940), Listeria innocua (Seeliger, 1981), Listeria seeligeri (Rocourt and Grimont, 1983), Listeria welshimeri (Rocourt and Grimont, 1983), Listeria ivanovii (Seeliger et al, 1984), comprising the subspecies. One group consists of only one species, Listeria grayi (Errebo Larsen and Seeliger, 1966), one includes Listeria fleischmanii (Bertsch et al, 2013), comprising the subspecies L. fleischmannii subsp. The Listeria senu stricto group includes two pathogenic species, L. monocytogenes and L. ivanovii. L. ivanovii is an animal pathogen (Gill et al, 1997; Chand and Sadana, 1999)

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