Condition-Specific Molecular Network Analysis Revealed That Flagellar Proteins Are Involved in Electron Transfer Processes of Shewanella piezotolerans WP3

Because of the ability to metabolize a large number of electron acceptors such as nitrate, nitrite, fumarate, and metal oxides, Shewanella species have attracted much attention in recent years. Generally, the use of these electron acceptors is mainly achieved through electron transfer proteins and their interactions which will dynamically change across different environmental conditions in cells. Therefore, functional analysis of condition-specific molecular networks can reveal biological information on electron transfer processes. By integrating expression data and molecular networks, we constructed condition-specific molecular networks for Shewanella piezotolerans WP3. We then identified condition-specific key genes and studied their potential functions with an emphasis on their roles in electron transfer processes. Functional module analysis showed that different flagellar assembly modules appeared under these conditions and suggested that flagellar proteins are important for these conditions. We also identified the electron transfer modules underlying these various environmental conditions. The present results could help with screening electron transfer genes and understanding electron transfer processes under various environmental conditions for the Shewanella species.

Primary Processing and Storage Affect the Dominant Microbiota of Fresh and Chill-Stored Sea Bass Products

The cultivable microbiota isolated from three sea bass products (whole, gutted, and filleted fish from the same batch) during chilled storage and the effect of primary processing on microbial communities in gutted and filleted fish were studied. Microbiological and sensory changes were also monitored. A total of 200 colonies were collected from TSA plates at the beginning and the end of fish shelf-life, differentiated by High Resolution Sequencing (HRM) and identified by sequencing analysis of the V3–V4 region of the 16S rRNA gene. Pseudomonas spp. followed by potential pathogenic bacteria were initially found, while Pseudomonasgessardii followed by other Pseudomonas or Shewanella species dominated at the end of fish shelf-life. P. gessardii was the most dominant phylotype in the whole sea bass, P. gessardii and S. baltica in gutted fish, while P. gessardii and P. fluorescens were the most dominant bacteria in sea bass fillets. To conclude, primary processing and storage affect microbial communities of gutted and filleted fish compared to the whole fish. HRM analysis can easily differentiate bacteria isolated from fish products and reveal the contamination due to handling and/or processing, and so help stakeholders to immediately tackle problems related with microbial quality or safety of fish.

Thermal destabilization mechanism of cytochrome c' from psychrophilic Shewanella violacea

Cytochrome c' is a nitric oxide (NO)-binding heme protein found in Gram negative bacteria. The thermal stability of psychrophilic Shewanella violacea cytochrome c' (SVCP) is lower than those of its homologues from other two psychrophilic Shewanella species, indicating that thermal destabilization mechanism for low-temperature adaptation accumulates in SVCP. In order to understand this mechanism at the amino acid level, here the stability and function of SVCP variants, modeled using the two homologues, were examined. The variants exhibited increased stability, and they bound NO similar to the wild-type. The vulnerability as to the SVCP stability could be attributed to less hydrogen bond at the subunit interface, more flexible loop structure, and less salt bridge on the protein surface, which appear to be its destabilization mechanism. This study provides an example for controlling stability without spoiling function in psychrophilic proteins.

An uncommon cause of soft tissue and knee infection after penetrating injury in a non-immunocompromised adolescent male

Non-cholerae Vibrio species and Shewanella species are organisms that rarely infect humans. Symptoms can range from gastroenteritis to wound infections to septicemia. In addition, these infections can lead to multiple poor outcomes ranging from amputations to death. We present a case of an 11-year-old male with prepatellar bursitis of the right knee due to Vibrio parahaemolyticus and Shewanella algae following an open wound in the Gulf of Mexico complicated by retained oyster shell fragments. He completely recovered after removal of the foreign bodies and organism-directed antimicrobial therapy with ciprofloxacin and doxycycline.

Description of Shewanella salipaludis sp. nov., isolated from a salt marsh

ABSTRACT A Gram-stain-negative and flagellated bacterial strain, SHSM-M6T, was isolated from salt marsh from Yellow Sea, Republic of Korea. Neighbor-joining phylogenetic tree of 16S rRNA gene sequences showed that strain SHSM-M6T belongs to the genus Shewanella. 16S rRNA gene sequence similarity values between strain SHSM-M6T and the type strains of Shewanella species were <98.0%. The average nucleotide identity and DNA–DNA hybridization values between genomic sequences of strain SHSM-M6T and the type strains of Shewanella species were <73.3 and 20.7%, respectively. Strain SHSM-M6T contained MK-6 as predominant menaquinone and Q-7 and Q-8 as the predominant ubiquinones. The novel strain contained C16:1ω7c and/or C16:1ω6c, iso-C15:0 and C16:0 as major fatty acids. Major polar lipids of strain SHSM-M6T were phosphatidylethanolamine, phosphatidylglycerol, one unidentified lipid, one unidentified aminolipid and one unidentified phospholipid. Differential phenotypic properties of strain SHSM-M6T, together with its phylogenetic and genetic distinctiveness, revealed that strain SHSM-M6T is separated from recognized Shewanella species. On the basis of the data presented, strain SHSM-M6T is considered to represent a novel species of the genus Shewanella, for which the name Shewanella salipaludis sp. nov. is proposed. The type strain is SHSM-M6T (=KACC 19901T = NBRC 113646T).

Crab bite causing shewanella putrefaciens infection: Introduction to a possibly deadly and emerging threat

Shewanella species are gram-negative bacteria found in warm, temperate regions and are normal microflora of the marine environment1. Human infections are unusual and have a restricted geographic distribution. Presentation: A 45 years old lady was bitten by a crab while preparing to cook it. She developed fever and swelling of the right thumb with hemoserous discharge and blackish discolouration.Upon examination, the thumb was erythematous and swollen with a hematoma filled blister formation over the dorsal aspect. Deblistering was done and fluid samples were sent for culture and sensitivity which later returned as Shewanella Putrefaciens. Empirically she was started on IV Augmentin. Discussion: Most common clinical manifestation associated with Shewanella spp are superficial soft tissue infection1. Other reported clinical features are primary and secondary bacteremia, hepatobiliary, bone, joint and CNS infection, endocarditis, eye, ear and respiratory infection2. Antibiotics susceptibility includes aminoglycosides, 3rd and 4th generation cephalosporins, carbapenems and fluoroquinolones1. About 79% of patients have underlying conditions such as diabetes mellitus, venous congestion and heart failure; they are immunocompromised, as is our patient3. Conclusion: Proper handling of seafood during preparation should be encouraged as a simple bite may turn deadly. Initiation of antibiotics according to suspected organisms should be performed to prevent worsening of soft tissue infections. References: Diaz, J.H, Lopez, F.A Skin, Soft Tissue and Systemic Bacterial Infections Following Aquatic Injuries and Exposures. The American Journal of the Medical Sciences, 349(3), 269275 Finkelstein,R, Oren,I. Soft Tissue Infections Caused by Marine Bacterial Pathogens: Epidemiology, Diagnosis, and Management. Current Infectious Disease Report (2011)13(5):470–477 N. Vignier et al; Human Infection with Shewanella putrefaciens and S. algae: Report of 16 Cases in Martinique and Review of the Literature; Am. J. Trop. Med. Hyg., 89(1), 2013, pp. 151–156