Transcriptomic Analysis of (Group I) Clostridium botulinum ATCC 3502 Cold Shock Response

Abstract

Profound understanding of the mechanisms foodborne pathogenic bacteria utilize in adaptation to the environmental stress they encounter during food processing and storage is of paramount importance in design of control measures. Chill temperature is a central control measure applied in minimally processed foods; however, data on the mechanisms the foodborne pathogen Clostridium botulinum activates upon cold stress are scarce. Transcriptomic analysis on the C. botulinum ATCC 3502 strain upon temperature downshift from 37°C to 15°C was performed to identify the cold-responsive gene set of this organism. Significant up- or down-regulation of 16 and 11 genes, respectively, was observed 1 h after the cold shock. At 5 h after the temperature downshift, 199 and 210 genes were up- or down-regulated, respectively. Thus, the relatively small gene set affected initially indicated a targeted acute response to cold shock, whereas extensive metabolic remodeling appeared to take place after prolonged exposure to cold. Genes related to fatty acid biosynthesis, oxidative stress response, and iron uptake and storage were induced, in addition to mechanisms previously characterized as cold-tolerance related in bacteria. Furthermore, several uncharacterized DNA-binding transcriptional regulator-encoding genes were induced, suggesting involvement of novel regulatory mechanisms in the cold shock response of C. botulinum. The role of such regulators, CBO0477 and CBO0558A, in cold tolerance of C. botulinum ATCC 3502 was demonstrated by deteriorated growth of related mutants at 17°C.

Genomic insights into temperature-dependent transcriptional responses ofKosmotoga olearia, a deep-biosphere bacterium that can grow from 20°C to 79°C

“…Re-modelling of amino acid metabolism at low temperatures has also been observed in other 512 bacteria (e.g., (Dahlsten et al, 2014;Ghobakhlou et al, 2015)). Interestingly, the genome of strictly 513 mesophilic M. prima encodes more genes involved in amino acid metabolism than the genomes of 514 thermophilic K. olearia and other Thermotogae .…”

“…At 30°C there was also significant up-regulation of a citrate synthase gene 390 (Kole_1230), suggesting that K. olearia cells may accumulate citrate, as was observed in 391Staphylococcus aureus during prolonged cold stress(Alreshidi et al 2015). Alternatively, citrate 392 synthase, together with isocitrate dehydrogenase (Kole_1227), may be involved in converting 393 pyruvate or acetyl-CoA to 2-oxoglutarate, a precursor for several amino acids including arginine, 394 which has been suggested to accumulate in for instance Clostridium(Dahlsten et al 2014). 395Interestingly, the genome of strictly mesophilic M. prima encodes more genes involved in amino acid 396 metabolism than the genomes of K. olearia and other thermophilic Thermotogae (Zhaxybayeva et al 397…”

Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502

“…botulinum subjected to cold shock [27]. Transcription of recA , encoding a protein that initiates the cleavage of LexA which leads to de-repression of the SOS system, was up-regulated from 10 min after heat shock onwards.…”

Genomic insights into temperature-dependent transcriptional responses of Kosmotoga olearia, a deep-biosphere bacterium that can grow from 20 to 79 °C

“…One of the strategies for maintenance of proper cellular function at non-optimal temperatures (Pollo et al 2015 ) is accumulation of compatible solutes. Specifically, re-modeling of amino acid metabolism and the possible accumulation of amino acids as compatible solutes at low temperatures have been observed in bacteria (e.g., Dahlsten et al 2014 ; Ghobakhlou et al 2015 ). The up-regulation of many genes involved in amino acid metabolism suggests that K. olearia may also accumulate amino acids or their intermediates for this purpose, especially at 30 °C.…”

“…At 30 °C, there was also significant up-regulation of a citrate synthase gene (Kole_1230), suggesting that K. olearia cells may accumulate citrate, as was observed in Staphylococcus aureus during prolonged cold stress (Alreshidi et al 2015 ). Alternatively, citrate synthase, together with isocitrate dehydrogenase (Kole_1227), may be involved in converting pyruvate or acetyl-CoA to 2-oxoglutarate, a precursor for several amino acids including arginine, which has been suggested to accumulate in for instance Clostridium (Dahlsten et al 2014 ). Interestingly, the genome of strictly mesophilic M. prima encodes more genes involved in amino acid metabolism than the genomes of K. olearia and other thermophilic Thermotogae (Zhaxybayeva et al 2012 ).…”