Comparative proteomic analysis of Cronobacter sakazakii by iTRAQ provides insights into response to desiccation

A universal mechanism on desiccation tolerance of Cronobacter based on intracellular trehalose accumulation regulated by EnvZ/OmpR

Cronobacter (seven species) can survive in dry powdered infant formula for a long time, but the thorough molecular mechanism of resistance to desiccation remains elusive. Here we examine the regulation mechanism of Cronobacter's tolerance to desiccation by the typical two-component system (TCS) EnvZ/OmpR. When exposed to desiccation conditions, Cronobacter showed higher survival than other pathogens, as well as significantly up-regulated expression of ompR and otsAB genes with markedly decreased survival of their mutants, suggesting their relationship with desiccation tolerance. OmpR directly binds to the promoter of trehalose biosynthesis operon otsBA, significantly enhancing their expression, and boosting the trehalose levels. The ompR-deletion in other six species further confirmed its positive regulation in desiccation tolerance. Our data present a hypothesis that EnvZ/OmpR increases intracellular trehalose levels against damage to the cells, which prompts Cronobacter to survive in desiccation conditions. This study reveals a universal molecular mechanism for desiccation resistance in Cronobacter species.

Maltodextrin-binding protein as a key factor in Cronobacter sakazakii survival under desiccation stress

Cronobacter sakazakii (C. sakazakii) is a notorious pathogen responsible for infections in infants and newborns, often transmitted through contaminated infant formula. Despite the use of traditional pasteurization methods, which can reduce microbial contamination, there remains a significant risk of pathogenic C. sakazakii surviving due to its exceptional stress tolerance. In our study, we employed a comparative proteomic approach by comparing wild-type strains with gene knockout strains to identify the essential genes crucial for the successful survival of C. sakazakii during desiccation. Our investigation revealed the significance of envZ-ompR, recA, and flhD gene cassettes in contributing to desiccation tolerance in C. sakazakii. Furthermore, through our comparative proteomic profiling, we identified the maltodextrin-binding protein encoded by ESA_03421 as a potential factor influencing dry tolerance. This protein is regulated by EnvZ-OmpR, RecA, and FlhD. Notably, the knockout of ESA_03421 resulted in a 150% greater reduction in Log CFU compared to the wild-type C. sakazakii. Overall, our findings offer valuable insights into the mechanisms underlying C. sakazakii desiccation tolerance and provide potential targets for the development of new antimicrobial strategies aimed at reducing the risk of infections in infants and newborns.

LuxS-deficiency reduces persistence of Cronobacter to low-moisture but contributes to virulence after rehydration

Low-moisture foods (LMF) have arisen an increasing concern as vehicles of foodborne pathogens. Cronobacter genus, a class A pathogen in powdered infant formula (PIF), is crucial to the safety of LMF. Researchers have concentrated more on the bacterial survival caused by key hazardous factors, yet they often ignore the alteration of virulence properties in the surviving strains following rehydration of LMF mediated by the key factors. Our previous transcriptional profiling showed that luxS might participate in desiccation response. Herein, we further investigated the role of Cronobacter LuxS under desiccation stress by combining with the phenotypic and gene analysis between the Cronobacter parent and luxS mutant strains. Desiccation stress destructing assays confirmed that luxS can significantly enhance the resistance of Cronobacter towards desiccation. Our results also showed that cell hydrophobicity, aggregation, motility, the content of polysaccharide, and AI-2 synthesis pathway involved in luxS-mediated desiccation response. The luxS mutant strain exhibited higher swimming and swarming motility, more content of capsular polysaccharide, and more rapid of aggregation, but lower hydrophobicity than that of the wild-type strain, whereas desiccation stress would result in a opposite effect on these cell surface properties in ΔluxS during rehydration. Additionally, the comparation of gene expression profiles indicated that low moisture would trigger Cronobacter luxS to promote transport osmoprotectants by regulating the expression of proX, proW, and treC, and suppress the expression of cpsG associated with polysaccharide colanic acid. Notably, this study also discovered for the first time that the luxS-deficiency dramatically attenuated adhesion and invasion to intestinal and brain cells, but ΔluxS subjected to desiccation could aggravate the cell virulence instead. Therefore, thinking the alteration of toxicity caused by low-moisture, approach based on blocking the expression of the luxS gene to prevent Cronobacter in LMF needs to be adopted with caution.

Environmental risk factors associated with the survival, persistence, and thermal tolerance of Cronobacter sakazakii during the manufacture of powdered infant formula

Cronobacter sakazakii is an opportunistic foodborne pathogen of concern for foods having low water activity such as powdered infant formula (PIF). Its survival under desiccated stress can be attributed to its ability to adapt effectively to many different environmental stresses. Due to the high risk to neonates and its sporadic outbreaks in PIF, C. sakazakii received great attention among the scientific community, food industry and health care providers. There are many extrinsic and intrinsic factors that affect C. sakazakii survival in low-moisture foods. Moreover, short- or long-term pre-exposure to sub-lethal physiological stresses which are commonly encountered in food processing environments are reported to affect the thermal resistance of C. sakazakii. Additionally, acclimation to these stresses may render C. sakazakii resistance to antibiotics and other antimicrobial agents. This article reviews the factors and the strategies responsible for the survival and persistence of C. sakazakii in PIF. Particularly, studies focused on the influence of various factors on thermal resistance, antibiotic or antimicrobial resistance, virulence potential and stress-associated gene expression are reviewed.

Proteomics reveals energy limitation and amino acid consumption as antibacterial mechanism of linalool against Shigella sonnei and its application in fresh beef preservation

Meat is often contaminated by food-borne pathogens, resulting in significant economic losses. Linalool from plant essential oils (EOs) has been reported to have excellent antibacterial properties. Therefore, this study aims to elucidate the mechanism of linalool against Shigella sonnei (S. sonnei) based on proteomic and physiological indicators. The results indicated that linalool severely perturbed the expression levels of intracellular proteins, of which 208 were up-regulated and 49 were down-regulated. Moreover, linalool exerted its inhibitory effect mainly through the induction of amino acid limitation and insufficient energy levels based on the pathways involved in differential expressed proteins (DEPs). After 8 h, alkaline phosphatase (AKP) leakage increased 20.96 and 21.52-fold in the MIC and 2MIC groups while protein leakage increased 2.17 and 2.50-fold, respectively, which revealed the potential of linalool on cell structure damage combined with nucleic acid leakage. In addition, the ATP content decreased to 36.92% and 18.84% in the MIC and 2MIC groups, respectively when processed for 8 h. In particular, linalool could effectively control the quality change of fresh beef by measuring pH, total volatile basic nitrogen (TVB-N), total viable counts (TVC) while not affecting its sensory acceptability based on the result of sensory evaluation. This research provides theoretical insights for the development of linalool as a new natural antibacterial agent.

Proteomic analysis reveals oxidative stress-induced activation of Hippo signaling in thiamethoxam-exposed Drosophila

Thiamethoxam (THIA) is a widely used neonicotinoid insecticide. However, the toxicity and defense mechanisms activated in THIA-exposed insects are unclear. Here, we used isobaric tags for relative and absolute quantitation (iTRAQ) proteomics technology to identify changes in protein expression in THIA-exposed Drosophila. We found that the antioxidant proteins Cyp6a23 and Dys were upregulated, whereas vir-1 was downregulated, which may have been detoxification in response to THIA exposure. Prx5 downregulation promoted the generation of reactive oxygen species. Furthermore, the accumulation of reactive oxygen species led to the induction of antioxidant defenses in THIA-exposed Drosophila, thereby enhancing the levels of oxidative stress markers (e.g., superoxide dismutase, glutathione S-transferase, and glutathione) and reducing catalase expression. Furthermore, the Hippo signaling transcription coactivator Yki was inactivated by THIA. Our results suggesting that Hippo signaling may be necessary to promote insect survival in response to neonicotinoid insecticide toxicity.

Transcriptomic analysis reveals novel desiccation tolerance mechanism of Cronobacter based on type VI secretion system inhibition

Cronobacter malonaticus (C. malonaticus) is a food-borne pathogen inducing severe infections both in infants and adults, and it could survive in dry powdered infant formula (PIF) for a long time, implying its strong tolerance to desiccation. However, the thorough molecular mechanism of resistance to desiccation remains elusive. When C. malonaticus was exposed to desiccation conditions (7, 15, and 30 d), transcriptomic analysis provided a universal adaptation strategy to withstand desiccation with the increased compatible solutes accumulation, activated stress resistance-related regulators, suppressed protein export and bacterial secretion system, and reduced other unessential survival functions including adhesion, invasion, virulence, and flagellar motility. Importantly, type VI secretion system (T6SS) genes exhibited significantly downregulated expressions, as well as markedly increased survival and viability of their mutants after desiccation treatment, revealing the negative regulation of T6SS in desiccation tolerance. Meanwhile, the decreased expressions of T6SS structure genes in other six species further confirmed the vital role of T6SS in desiccation tolerance of Cronobacter spp. Thus, our studies present a novel hypothesis of desiccation resistance in Cronobacter based on type VI secretion system inhibition, causing the reduction of macromolecule secretion such as effectors and hyperosmolality development within the cytomembrane, which allow Cronobacter to survive in desiccation.

Transcriptomic and proteomic analysis of Staphylococcus aureus response to cuminaldehyde stress

The previous study indicated that cuminaldehyde (CUM) could be used as an antibacterial agent in sauced beef to reduce the propagation of Staphylococcus aureus (S. aureus). This research took sauced beef treated with 0.4 μL/mL CUM as the research object. Transcriptomic and proteomic methods were used to comprehensively analyze the changes in genes and proteins of S. aureus under CUM stress. A total of 258 differentially expressed genes (DEGs, 178 up-regulated and 80 down-regulated) and 384 differentially expressed proteins (DEPs, 61 up-regulated and 323 down-regulated) were found. It was observed that CUM destroyed the cell wall and cell membrane by inhibiting the synthesis of peptidoglycan and fatty acid. Low energy consumption strategies were formed by reducing glycolysis and ribosome de novo synthesis. The levels of genes and proteins associated with the glycine, serine, threonine, methionine, cysteine, and branched-chain amino acids were dramatically changed, which impaired protein synthesis and reduced bacterial viability. In addition, the up-regulated DEGs and DEFs involved in DNA replication, recombination and single-stranded DNA-binding contributed to DNA repair. Moreover, ATP-binding cassettes (ABC) transporters were also perturbed, such as the uptake of betaine and iron were inhibited. Thus, this study revealed the response mechanism of S. aureus under the stress of CUM, and provided a theoretical basis for the application of CUM in meat products.

TMT-Based Quantitative Proteomic Analysis of Intestinal Organoids Infected by Listeria monocytogenes Strains with Different Virulence

L. monocytogenes, consisting of 13 serotypes, is an opportunistic food-borne pathogen that causes different host reactions depending on its serotypes. In this study, highly toxic L. monocytogenes 10403s resulted in more severe infections and lower survival rates. Additionally, to investigate the remodeling of the host proteome by strains exhibiting differential toxicity, the cellular protein responses of intestinal organoids were analyzed using tandem mass tag (TMT) labeling and high-performance liquid chromatography−mass spectrometry. The virulent strain 10403s caused 102 up-regulated and 52 down-regulated proteins, while the low virulent strain M7 caused 188 up-regulated and 25 down-regulated proteins. Based on the analysis of gene ontology (GO) and KEGG databases, the expressions of differential proteins in organoids infected by L. monocytogenes 10403s (virulent strain) or M7 (low virulent strain) were involved in regulating essential processes such as the biological metabolism, the energy metabolism, and immune system processes. The results showed that the immune system process, as the primary host defense response to L. monocytogenes, comprised five pathways, including ECM−receptor interaction, the complement and coagulation cascades, HIF-1, ferroptosis, and NOD-like receptor signaling pathways. As for the L. monocytogenes 10403s vs. M7 group, the expression of differential proteins was involved in two pathways: systemic lupus erythematosus and transcriptional mis-regulation in cancer. All in all, these results revealed that L. monocytogenes strains with different toxicity induced similar biological functions and immune responses while having different regulations on differential proteins in the pathway.

Chemotaxis and Shorter O-Antigen Chain Length Contribute to the Strong Desiccation Tolerance of a Food-Isolated Cronobacter sakazakii Strain

Cronobacter sakazakii is an opportunistic pathogen causing a lethality rate as high as 80% in infants. Desiccation tolerance ensures its survival in powdered infant formula (PIF) and contributes to the increased exposure to neonates, resulting in neonatal meningitis, septicemia, and necrotizing enterocolitis. This study showed that a food-isolated C. sakazakii G4023 strain exhibited a stronger desiccation tolerance than C. sakazakii ATCC 29544 strain. Considering the proven pathogenicity of G4023, it could be a big threat to infants. Transcriptome and proteome were performed to provide new insights into the desiccation adaptation mechanisms of G4023. Integrated analyses of these omics suggested that 331 genes were found regulated at both transcriptional and protein levels (≥2.0- and ≥1.5-fold, respectively). Deletion of chemotaxis system encoded genes cheA and cheW resulted in decreased tolerance in both short- and long-term desiccation. Reduced O-antigen chain length contributed to the biofilm formation and desiccation tolerance in the short term rather than the long term. In addition, biosynthesis of flagella, arginine and its transport system, and Fe/S cluster were also observed regulated in desiccated G4023. A better understanding of desiccation adaptation mechanisms of G4023 could in turn guide the operations during production and preservation of PIF or other food to reduce survival odds of G4023 and lower its exposure to get to infants.

Performance evaluation and mechanism of nitrogen removal in a packed bed reactor using micromagnetic carriers at different carbon to nitrogen ratios

Advanced nitrogen removal of effluent discharged from secondary treatment systems can avoid eutrophication. However, the lack of biodegradable organics limits biodenitrification. Packed bed reactors filled with carriers with different micromagnetic field (MMF) strengths were used to perform tertiary denitrification. The results showed that MMF significantly improved the denitrification performance, especially at low C/N ratios. Total nitrogen (TN) removal was increased by 4.12% with 0.6 mT MMF when C/N = 4 and increased by 7.06% and 8.06% with 0.3 mT and 0.9 mT MMFs when C/N = 3, respectively. Zooglea, Flavobacterium, and Denitratisoma contributed to the advanced denitrification performance under MMF. In addition, 0.6 mT MMF enhanced nitrogen metabolism and ABC transporter protein and two-component system activities of microorganisms under C/N = 4; 0.3 mT and 0.9 mT MMFs increased nitrogen, carbohydrate, and amino acid metabolism and ABC transporter protein activities under C/N = 3. These findings indicate that MMF has great potential for advanced denitrification from secondary effluent.

Invited review: Stress resistance of Cronobacter spp. affecting control of its growth during food production

Members of the Cronobacter genus include food-borne pathogens that can cause infections in infants, with a mortality rate as high as 40 to 80%. The high fatality rate of Cronobacter and its isolation from numerous types of food, especially from powdered infant formula, demonstrate the serious nature of this organism. The source tracking of Cronobacter spp. and the analysis of high-frequency species from different sources are helpful for a more targeted control. Furthermore, the persistence during food processing and storage may be attributed to strong resistance of Cronobacter spp. to environment stresses such as heat, pH, and desiccation. There are many factors that support the survival of Cronobacter spp. in harsh environments, such as some genes, regulatory systems, and biofilms. Advanced detection technology is helpful for the strict monitoring of Cronobacter spp. In addition to the traditional heat treatment, many new control techniques have been developed, and the ability to control Cronobacter spp. has been demonstrated. The control of this bacteria is required not only during manufacture, but also through the selection of packaging methods to reduce postprocessing contamination. At the same time, the effect of inactivation methods on product quality and safety must be considered. This review considers the advances in our understanding of environmental stress response in Cronobacter spp. with special emphasis on its implications in food processing.

Potassium regulates the growth and toxin biosynthesis of Microcystis aeruginosa

Potassium (K⁺) is the most abundant cation in phytoplankton cells, but its impact on Microcystis aeruginosa (M. aeruginosa) has not been fully documented. This study presents evidence of how K⁺ availability affects the growth, oxidative stress and microcystin (MC) production of M. aeruginosa. The iTRAQ-based proteomic analysis revealed that during K⁺ deficiency, serious oxidative damage occurred and the photosynthesis-associated and ABC transporter-related proteins in M. aeruginosa were substantially downregulated. In the absence of K⁺, a 69.26% reduction in cell density was shown, and both the photosynthesis and iron uptake were depressed, which triggered a declined production of ATP and expression of MC synthetases genes (mcyA, B and D), and MC exporters (mcyH). Through the impairment of both the MC biosynthesis and MC transportation out of cells, K⁺ depletion caused an 85.89% reduction of extracellular MC content at the end of the study. However, with increasing in the available K⁺ concentrations, photosynthesis efficiency, the expression of ABC-transporter proteins, and the transcription of mcy genes displayed slight differences compared with those in the control group. This work represents evidence that K⁺ availability can regulate the physiological metabolic activity of M. aeruginosa and K⁺ deficiency leads to depressed growth and MC production in M. aeruginosa.

Comparative Proteomic Analysis of Adhesion/Invasion Related Proteins in Cronobacter sakazakii Based on Data-Independent Acquisition Coupled With LC-MS/MS

Cronobacter sakazakii is foodborne pathogen that causes serious illnesses such as necrotizing enterocolitis, meningitis and septicemia in infants. However, the virulence determinants and mechanisms of pathogenicity of these species remain unclear. In this study, multilocus sequence typing (MLST) was performed on 34 C. sakazakii strains and two strains with the same sequence type (ST) but distinct adhesion/invasion capabilities were selected for identification of differentially expressed proteins using data-independent acquisition (DIA) proteomic analysis. A total of 2,203 proteins were identified and quantified. Among these proteins, 210 exhibited differential expression patterns with abundance ratios ≥3 or ≤0.33 and P values ≤0.05. Among these 210 proteins, 67 were expressed higher, and 143 were expressed lower in C. sakazakii SAKA80220 (strongly adhesive/invasive strain) compared with C. sakazakii SAKA80221 (weakly adhesive/invasive strain). Based on a detailed analysis of the differentially expressed proteins, the highly expressed genes involved in flagellar assembly, lipopolysaccharide synthesis, LuxS/AI-2, energy metabolic pathways and iron-sulfur cluster may be associated with the adhesion/invasion capability of C. sakazakii. To verify the accuracy of the proteomic results, real-time qPCR was used to analyze the expression patterns of some genes at the transcriptional level, and consistent results were observed. This study, for the first time, used DIA proteomic to investigate potential adhesion/invasion related factors as a useful reference for further studies on the pathogenic mechanism of C. sakazakii.

Label free-based proteomic analysis of Escherichia coli O157:H7 subjected to ohmic heating

To investigate the inactivation mechanism of ohmic heating (OH) on Escherichia coli O157:H7 at the same inactivation levels, a label-free quantitative proteomic approach was employed in this study. Quantification of 2633 proteins was obtained with high confidence. Compared to untreated samples (CT), a total of 169, 84, and 26 proteins showed significantly differential abundance after high voltage OH (HVOH, 10 V/cm), low voltage OH (LVOH, 5 V/cm), and water bath heating (WB), respectively. Glyoxylate and dicarboxylate metabolism, ABC transporters, biosynthesis of amino acids, glycerophospholipid metabolism, and ribosome pathway were the main KEGG pathways mediated by OH, but only ribosome pathway was greatly affected by WB. The significant differences in proteome changes of E. coli O157:H7 among HVOH, LVOH, and WB treatments, especially the greater number of differential proteins in HVOH, indicated that OH might exert additional effects on proteome of E. coli O157:H7 due to the electric current, particularly in HVOH with higher electric field. This result enriched our understanding of molecular changes of E. coli O157:H7 induced by OH and provided data reference for further research into the inactivation mechanism of OH.

Ethanol Adaptation Strategies in Salmonella enterica Serovar Enteritidis Revealed by Global Proteomic and Mutagenic Analyses

Salmonella enterica subsp. enterica serovar Enteritidis is able to adapt to sublethal concentrations of ethanol, which subsequently induce tolerance of this pathogen to normally lethal ethanol challenges. This work aims to elucidate the underlying ethanol adaptation mechanisms of S Enteritidis by proteomic and mutagenic analyses. The global proteomic response of S Enteritidis to ethanol adaptation (5% ethanol for 1 h) was determined by isobaric tags for relative and absolute quantification (iTRAQ), and it was found that a total of 138 proteins were differentially expressed in ethanol-adapted cells compared to nonadapted cells. A total of 56 upregulated proteins were principally associated with purine metabolism and as transporters for glycine betaine, phosphate, d-alanine, thiamine, and heme, whereas 82 downregulated proteins were mainly involved in enterobactin biosynthesis and uptake, the ribosome, flagellar assembly, and virulence. Moreover, mutagenic analysis further revealed the functions of two highly upregulated proteins belonging to purine metabolism (HiuH, 5-hydroxyisourate hydrolase) and glycine betaine transport (ProX, glycine betaine-binding periplasmic protein) pathways. Deletion of either hiuH or proX resulted in the development of a stronger ethanol tolerance response, suggesting negative regulatory roles in ethanol adaptation. Collectively, this work suggests that S Enteritidis employs multiple strategies to coordinate ethanol adaptation.IMPORTANCE Stress adaptation in foodborne pathogens has been recognized as a food safety concern since it may compromise currently employed microbial intervention strategies. While adaptation to sublethal levels of ethanol is able to induce ethanol tolerance in foodborne pathogens, the molecular mechanism underlying this phenomenon is poorly characterized. Hence, global proteomic analysis and mutagenic analysis were conducted in the current work to understand the strategies employed by Salmonella enterica subsp. enterica serovar Enteritidis to respond to ethanol adaptation. It was revealed that coordinated regulation of multiple pathways involving metabolism, ABC transporters, regulators, enterobactin biosynthesis and uptake, the ribosome, flagellar assembly, and virulence was responsible for the development of ethanol adaptation response in this pathogen. Such knowledge will undoubtedly contribute to the development and implementation of more-effective food safety interventions.

Profiling of Small Molecular Metabolites in Nostoc flagelliforme during Periodic Desiccation

The mass spectrometry-based metabolomics approach has become a powerful tool for the quantitative analysis of small-molecule metabolites in biological samples. Nostoc flagelliforme, an edible cyanobacterium with herbal value, serves as an unexploited bioresource for small molecules. In natural environments, N. flagelliforme undergoes repeated cycles of rehydration and dehydration, which are interrupted by either long- or short-term dormancy. In this study, we performed an untargeted metabolite profiling of N. flagelliforme samples at three physiological states: Dormant (S1), physiologically fully recovered after rehydration (S2), and physiologically partially inhibited following dehydration (S3). Significant metabolome differences were identified based on the OPLS-DA (orthogonal projections to latent structures discriminant analysis) model. In total, 183 differential metabolites (95 up-regulated; 88 down-regulated) were found during the rehydration process (S2 vs. S1), and 130 (seven up-regulated; 123 down-regulated) during the dehydration process (S3 vs. S2). Thus, it seemed that the metabolites’ biosynthesis mainly took place in the rehydration process while the degradation or possible conversion occurred in the dehydration process. In addition, lipid profile differences were particularly prominent, implying profound membrane phase changes during the rehydration–dehydration cycle. In general, this study expands our understanding of the metabolite dynamics in N. flagelliforme and provides biotechnological clues for achieving the efficient production of those metabolites with medical potential.

Coping with low water activities and osmotic stress in Acinetobacter baumannii: significance, current status and perspectives

Multidrug resistant (MDR) pathogens are one of the most pressing challenges of contemporary health care. Acinetobacter baumannii takes a predominant position, emphasized in 2017 by the World Health Organization. The increasing emergence of MDR strains strengthens the demand for new antimicrobials. Possible targets for such compounds might be proteins involved in resistance against low water activity environments, since A. baumannii is known for its pronounced resistance against desiccation stress. Despite the importance of desiccation resistance for persistence of this pathogen in hospitals, comparable studies and precise data on this topic are rare and the mechanisms involved are largely unknown. This review aims to give an overview of the studies performed so far and the current knowledge on genes and proteins important for desiccation survival. 'Osmotic stress' is not identical to 'desiccation stress', but the two share the response of bacteria to low water activities. Osmotic stress resistance is in general studied much better, and in recent years it turned out that accumulation of compatible solutes in A. baumannii comprises some special features such as the bifunctional enzyme MtlD synthesizing the unusual solute mannitol. Furthermore, the regulatory pathways, as understood today, will be discussed.

Characterization of the Desiccation Tolerance of Cronobacter sakazakii Strains

Strong desiccation tolerance is an outstanding feature of Cronobacter sakazakii and can enable the bacterium to survive in a dry food matrix (such as milk powder) for a long time. Therefore, contamination of food possessing low water activity with C. sakazakii can increase the risk of infection in human beings, particularly in neonates and infants. However, the mechanism underlying the desiccation tolerance property of C. sakazakii is largely unknown. In this study, the desiccation tolerance characteristics of 42 C. sakazakii strains were analyzed. Simultaneously, the sequence types and biofilm formation abilities of the strains were investigated, and their correlations with desiccation tolerance were analyzed. The results showed no significant correlation between desiccation tolerance and sequence type. However, there was a positive correlation between biofilm formation ability and desiccation tolerance. Raman spectroscopy was employed to investigate the biofilm formed by strains with distinct desiccation tolerance levels, and the results showed that the levels of polysaccharide, proteins and carotenoid might play important roles in the resistance to dry environments. In addition, 10 genes involved in osmoprotectant synthesis or transport were selected, and their differential expression in strains with diverse desiccation tolerance levels was compared to investigate whether these genes were responsible for cytoprotection in the dry environment. The results revealed a great difference in gene expression among strains with different desiccation tolerance levels, suggesting that these genes play a regulatory role in the resistance of C. sakazakii to dry environments. Our study provides a useful reference for follow-up studies investigating the mechanism of desiccation tolerance in C. sakazakii.