Advances in electrochemically active biofilm of Shewanella oneidensis MR-1 / 生物工程学报

Facing the increasingly severe energy shortage and environmental pollution, electrocatalytic processes using electroactive microorganisms provide a new alternative for achieving environmental-friendly production. Because of its unique respiratory mode and electron transfer ability, Shewanella oneidensis MR-1 has been widely used in the fields of microbial fuel cell, bioelectrosynthesis of value-added chemicals, metal waste treatment and environmental remediation system. The electrochemically active biofilm of S. oneidensis MR-1 is an excellent carrier for transferring the electrons of the electroactive microorganisms. The formation of electrochemically active biofilm is a dynamic and complex process, which is affected by many factors, such as electrode materials, culture conditions, strains and their metabolism. The electrochemically active biofilm plays a very important role in enhancing bacterial environmental stress resistance, improving nutrient uptake and electron transfer efficiency. This paper reviewed the formation process, influencing factors and applications of S. oneidensis MR-1 biofilm in bio-energy, bioremediation and biosensing, with the aim to facilitate and expand its further application.

Decolorization of the benzidine-based azo dye Congo red by the new strain Shewanella xiamenensis G5-03 / Descoloração do corante azo derivado da benzidina vermelho Congo por uma nova linhagem de Shewanella xiamenensis G5-03

Shewanella xiamenensis G5-03 was observed to decolorize the azo dye Congo red in synthetic wastewater. The influence of some factors on the dye decolorization efficiency was evaluated. The optimal decolorization conditions were temperature 30-35 °C, pH 10.0, incubation time 10 h, and static condition. The kinetic of Congo red decolorization fitted to the Michaelis–Menten model (Vmax = 111.11 mg L-¹ h-¹ and Km = 448.3 mg L-¹). The bacterium was also able to degrade benzidine, a product of azo bond breakage of the Congo red, which contributed to reduce the phytotoxicity. The ability of S. xiamenensis G5-03 for simultaneous decolorization and degradation of Congo red shows its potential application for the biological treatment of wastewaters containing azo dyes.

Shewanella xiamenensis G5-03 foi capaz de descolorir o corante azo vermelho Congo em água residuária sintética. A influência de alguns fatores na eficiência da descoloração do corante foi avaliada. As condições ótimas de descoloração foram temperatura de 30-35 °C, pH 10,0 e condições estáticas. A cinética de descoloração do vermelho Congo se ajustou ao modelo de Michaelis–Menten (Vmax = 111,11 mg L-¹ h-¹ and Km = 448,3 mg L-¹). A bactéria também foi capaz de degradar a benzidina, um produto da quebra da ligação azo do vermelho Congo, o que contribuiu para a redução da fitotoxicidade. A habilidade da S. xiamenensis G5-03 em simultaneamente descolorir e degradar o vermelho Congo demostra seu potencial de aplicação no tratamento de águas residuárias contendo corantes azo.

Decolorization of the benzidine-based azo dye Congo red by the new strain Shewanella xiamenensis G5-03 / Descoloração do corante azo derivado da benzidina vermelho Congo por uma nova linhagem de Shewanella xiamenensis G5-03

Shewanella xiamenensis G5-03 was observed to decolorize the azo dye Congo red in synthetic wastewater. The influence of some factors on the dye decolorization efficiency was evaluated. The optimal decolorization conditions were temperature 30-35 °C, pH 10.0, incubation time 10 h, and static condition. The kinetic of Congo red decolorization fitted to the Michaelis­Menten model (Vmax = 111.11 mg L-1 h-1 and Km = 448.3 mg L-1). The bacterium was also able to degrade benzidine, a product of azo bond breakage of the Congo red, which contributed to reduce the phytotoxicity. The ability of S. xiamenensis G5-03 for simultaneous decolorization and degradation of Congo red shows its potential application for the biological treatment of wastewaters containing azo dyes.

Shewanella xiamenensis G5-03 foi capaz de descolorir o corante azo vermelho Congo em água residuária sintética. A influência de alguns fatores na eficiência da descoloração do corante foi avaliada. As condições ótimas de descoloração foram temperatura de 30-35 °C, pH 10,0 e condições estáticas. A cinética de descoloração do vermelho Congo se ajustou ao modelo de Michaelis­Menten (Vmax = 111,11 mg L-1 h-1 and Km = 448,3 mg L-1). A bactéria também foi capaz de degradar a benzidina, um produto da quebra da ligação azo do vermelho Congo, o que contribuiu para a redução da fitotoxicidade. A habilidade da S. xiamenensis G5-03 em simultaneamente descolorir e degradar o vermelho Congo demostra seu potencial de aplicação no tratamento de águas residuárias contendo corantes azo.

Infectious Keratitis Caused by Shewanella Putrefaciens

PURPOSE: We report a case of infectious keratitis caused by Shewanella putrefaciens in a patient after fishing. CASE SUMMARY: A 75-year-old male with no underlying disease other than hypertension was admitted to our hospital because of decreased visual acuity and congestion in his left eye for 2 weeks. At the first ophthalmic examination, the best-corrected visual acuity (BCVA) of the left eye was counting fingers. Slit lamp examination showed stromal infiltrates with 2.0 × 2.0 mm corneal epithelial defects, endothelial inflammatory plaques and 1 mm height hypopyon with severe inflammation in the anterior chamber. Bacterial culture tests were performed by corneal scraping, which were positive for Shewanella putrefaciens, followed by treatment with moxifloxacin and ceftazidime topical antibiotics. After 2 months of treatment, the BCVA of the left eye improved to 0.4 and the corneal lesion clinically improved with residual mild stromal opacity. CONCLUSIONS: Shewanella putrefaciens should be considered as a causal pathogen of infectious keratitis in patients after fishing. We report a case of infectious keratitis caused by Shewanella putrefaciens, which has never previously been reported in the Republic of Korea.

Marine bacteria from the Gulf of California with antimicrofouling activity against colonizing bacteria and microalgae / Bacterias marinas del Golfo de California con actividad antimicrobiana frente a bacterias colonizadoras y microalgas

Abstract One way of reducing the input of pollutants into the marine environment is to enforce the use of non-toxic antifouling paints in marine protected areas. Thus, the purpose of this study was to detect marine microorganisms that secrete inhibitory substances against bacteria and microalgae to avoid biofouling on manmade structures in La Paz bay, B.C.S., Mexico. The inhibitory potential of 125 bacteria was evaluated against biofilm-forming bacteria. Crude extracts were obtained with methanol and ethyl acetate from 16 bacterial strains that exhibited antagonistic and antibacterial activity in a preliminary screening. Antibacterial and antimicroalgal assays were performed using crude extracts, the minimum inhibitory concentration (MIC) was determined. The highest activity against bacteria and microalgae was found in two strains, Shewanella algae and Staphylococcus sp. The results of this study suggest that extracts of bacteria from the Gulf of California with antimicrobial properties against biofilm-forming bacteria can also prevent the adhesion of microalgae, which may control the development of biofilm formation and, as a consequence, biofouling.(AU)

Resumen Una alternativa para reducir la contaminación en el medio marino es el uso de pinturas anti-incrustantes no tóxicas en áreas marinas protegidas. En el presente estudio se propuso encontrar microorganismos marinos que secreten sustancias capaces de inhibir la adhesión de bacterias y microalgas, de esta manera evitar la bioincrustación en estructuras marinas en la bahía de La Paz, B.C.S., México. Un total de 125 bacterias fueron evaluadas por su capacidad para inhibir el desarrollo de bacterias formadoras de biopelículas. En una selección preliminar de actividad antagónica y antibacteriana, 16 cepas bacterianas mostraron potencial actividad inhibitoria, de las que se obtuvieron los extractos crudos con metanol y acetato de etilo. Se realizaron ensayos antibacterianos y anti-microalgales utilizando los extractos crudos, se determinó la concentración mínima inhibitoria (MIC). Dos cepas mostraron la mayor actividad contra bacterias y microalgas: Shewanella algae y Staphylococcus sp. Los resultados de este estudio sugieren que los extractos de bacterias aisladas en el Golfo de California que poseen propiedades antimicrobianas contra las bacterias formadoras de biofilm y también pueden prevenir la adhesión de microalgas, con lo que se podría controlar el desarrollo de la formación de biopelículas y como consecuencia, el biofouling.(AU)

Emergence and Spread of OXA-48-Like Carbapenemase-Producing Enterobacteriaceae / 병원감염관리

Since 2001, ten more OXA-48 variants have been identified. Shewanella spp. has been thought to be the original host for OXA-48-like enzymes. These enzymes strongly hydrolyze penicillins and weakly hydrolyze carbapenems, with very weak activity against broad-spectrum cephalosporins. The OXA-48-like genes are always plasmid-borne and have been located in insertion sequences. OXA-48-like carbapenemases have been identified mainly from Turkey, North African countries, the Middle East, and India. Furthermore, the emergence and outbreak of OXA-48-like producers in Korea have been reported recently. Because some OXA-48-like-producing Enterobacteriaceae isolates do not exhibit resistance to broad-spectrum cephalosporins and only decreased susceptibility to carbapenems, their detection can be difficult. Adequate screening and detection methods are required to prevent and control the dissemination of OXA-48-like-producing Enterobacteriaceae.

Binding of Shewanella FadR to the fabA fatty acid biosynthetic gene: implications for contraction of the fad regulon

The Escherichia coli fadR protein product, a paradigm/prototypical FadR regulator, positively regulates fabA and fabB, the two critical genes for unsaturated fatty acid (UFA) biosynthesis. However the scenario in the other Ɣ-proteobacteria, such as Shewanella with the marine origin, is unusual in that Rodionov and coworkers predicted that only fabA (not fabB) has a binding site for FadR protein. It raised the possibility of fad regulon contraction. Here we report that this is the case. Sequence alignment of the FadR homologs revealed that the N-terminal DNA-binding domain exhibited remarkable similarity, whereas the ligand-accepting motif at C-terminus is relatively-less conserved. The FadR homologue of S. oneidensis (referred to FadR_she) was over-expressed and purified to homogeneity. Integrative evidence obtained by FPLC (fast protein liquid chromatography) and chemical cross-linking analyses elucidated that FadR_she protein can dimerize in solution, whose identity was determined by MALDI-TOF-MS. In vitro data from electrophoretic mobility shift assays suggested that FadR_she is almost functionally-exchangeable/equivalent to E. coli FadR (FadR_ec) in the ability of binding the E. coli fabA (and fabB) promoters. In an agreement with that of E. coli fabA, S. oneidensis fabA promoter bound both FadR_she and FadR_ec, and was disassociated specifically with the FadR regulatory protein upon the addition of long-chain acyl-CoA thioesters. To monitor in vivo effect exerted by FadR on Shewanella fabA expression, the native promoter of S. oneidensis fabA was fused to a LacZ reporter gene to engineer a chromosome fabA-lacZ transcriptional fusion in E. coli. As anticipated, the removal of fadR gene gave about 2-fold decrement of Shewanella fabA expression by β-gal activity, which is almost identical to the inhibitory level by the addition of oleate. Therefore, we concluded that fabA is contracted to be the only one member of fad regulon in the context of fatty acid synthesis in the marine bacteria Shewanella genus.

A Case of Spontaneous Bacterial Peritonitis with Bacteremia Caused by Shewanella algae

Human infection caused by Shewanella algae is rare, which usually occurred after direct contact with seawater or ingestion of raw seafood in the immunocompromised host. There have been anecdotal reports about Shewanella infections in human, but their pathogenic role and microbiologic data are limited. Here, we report a fatal case of spontaneous bacterial peritonitis with bacteremia due to S. algae in a 57-year-old male with liver cirrhosis who had no history of exposure to seawater or raw seafood. Polymicrobial infection with Streptococcus mitis and Escherichia coli was combined and the patient died in spite of early appropriate antimicrobial therapy and early goal-directed therapy for sepsis.

A Case of Endophthalmitis Caused by Shewanella algae after Trauma

PURPOSE: To report a rare case of endophthalmitis caused by Shewanella algae after trauma. CASE SUMMARY: A 27-year-old man was referred for trauma caused by a fishing sinker in his right eye. On initial examination at another hospital, his visual acuity was light perception, and intraocular pressure was 50 mm Hg. On slit lamp examination, corneal edema and severe anterior chamber inflammation were observed. Consequently, the next day total pars plana vitrectomy, lensectomy, intravitreal silicone oil injection, and antibiotics injection were performed. After the operation, intraocular pressure was 15 mm Hg and the patient's pain was temporarily decreased. The presence of Shewanella algae in the vitreous culture was determined but antibiotic sensitivity was not proven. The patient received postoperative topical fortified vancomycin, ceftazidime, and tobramycin hourly and underwent intravenous antibiotic therapy. On postoperative day 25, the patient transferred to our hospital and ocular pain presented continuously. Intraocular inflammation was not severe but visual acuity was light perception because of retinal necrosis in the posterior pole. Therefore, the patient received topical fortified antibiotics and intravenous antibiotics therapy. On postoperative month 2, visual acuity was light perception and the patient's right eye progressed to pthisis bulbi. CONCLUSIONS: Here in the first case reported in Korea or other conturies of primary endophthalmitis by Shewanella algae after traumas. Shewanella algae endophthalmitis has a rapid progression and poor visual prognosis in spite of aggressive therapy.

A Case of Shewanella algae Bacteremia Accompanying Cellulitis in Both Legs of a Patient on Hemodialysis: Case Report and Literature Review

We report a fatal case of Shewanella algae bacteremia accompanied by cellulitis in both legs of a chronic renal failure patient who had not been exposed to sea water or raw fish. A 47-year-old male on hemodialysis was admitted to our clinic due to pain in both legs accompanied by a febrile sensation that started 2 days prior to his visit. A blood culture specimen revealed S. algae, a rare human opportunistic pathogen. In spite of early and appropriate antimicrobial treatment, the patient died of septic shock on the second day of his hospital stay. Recently, serious infections caused by Shewanella species have been reported in increasing frequency. Hepatobiliary diseases have been proposed as predisposing factors, not only for infection by this organism, but also for fatality. However, we should be aware of the significance of S. algae in patients with renal insufficiency, especially those on maintenance hemodialysis. Herein, we report our case with review relevant literature.

Shewanella infection of snake bites: a twelve-year retrospective study

OBJECTIVE: Infections of snake bite wounds by Shewanella are rarely discussed in the medical literature. This study aims to characterize the presentation and management of Shewanella infections in snake bite wounds. METHOD: We retrospectively investigated the microbiology, clinical features, and outcomes of patients with Shewanella infected snake bite wounds admitted to a tertiary medical center from January 1998 to December 2009. RESULTS: Ten patients with Shewanella-infected snake bite wounds were identified. All of the snake bites were caused by cobras. The majority of patients had moderate to severe local envenomation and polymicrobial infections. Shewanella isolates are susceptible to ampicillin-sulbactam, piperacillin-tazobactam, third-and fourthgeneration cephalosporins, carbapenems, aminoglycosides, and quinolones but are resistant to penicillin and cefazolin. All of the patients examined had favorable outcomes. CONCLUSION: It is recommended that Shewanella infection be considered in snake bite patients, especially when patients present with moderate to severe local envenomation.

Analizan la diseminación de determinantes de resistencia a antibióticos del género Shewanella en el ambiente hospitalario / Analysis of antimicrobial resistance determinants associated with antibiotics of the genus Shewanella in a hospital environment

La alta frecuencia de diseminación de estos determinantes pone de manifiesto la capacidad de este género para actuar como reservorio y a su vez vector de la resistencia antibiótica

Shewanella algae en un paciente con diarrea crónica: primer caso en Costa Rica / Shewanella algae in a patient with chronic diarrhea: first case in Costa Rica

Se presenta el caso de un paciente masculino, vecino de Pavas-San José, con historia de diarrea crónica. En el coprocultivo se identificó shewanella algae. Casos de infección en humanos por esta bacteria son raros y se han encontrado, predominantemente localizadas, en piel, oídos y tejidos blandos con o sin bacteremia, en la mayoría de los cuales existe el antecedente de contacto con ambientes marinos. Shewanella algae es sensible a aminoglicósidos, carbapanemes, eritromicina y quinolonas, pero resistente a penicilinas. La sensibilidad a ampicilina y cefalosporinas es variable. Nuestro paciente fue tratado con cefalexina y tuvo una respuesta satisfactoria al mismo, con cese de los síntomas. De acuerdo con nuestro conocimiento este el primer caso documentado, en Costa Rica, de infección gastrointestinal por esta bacteria.

We report herein the case of a male patient, from Pavas, San Jose, with chronic diarrhea whose stool culture grew Shewanella algae. Infections caused by this micro-organism are infrequent and most commonly involve ears, skin and soft tissue, with or without bacteremia and are usually linked to ocean contact in warm climate countries. Shewanella algae is sensitive to aminoglycosides, carbapenems, erythromycin and quinolones, but resistant to penicillin. Sensitivity to amplicilin and cephalosporins is variable. Our patient was treated withcefalexin, with satisfactory results. To our knowledge, this is the first documented case in Costa Rica of gastrointestinal infection caused by this microorganism.

Primary Shewanella algae Bacteremia Mimicking Vibrio Septicemia

Shewanella algae infections are rare in humans. Previously reported cases of S. algae have mainly been associated with direct contact with seawater. We report a case of primary S. algae bacteremia occurring after the ingestion of raw seafood in a patient with liver cirrhosis that presented a fulminent course of necrotizing fasciitis.

Development of bioconcrete material using an enrichment culture of novel thermophilic anaerobic bacteria.

In the biosphere, bacteria can function as geo-chemical agents, promoting the dispersion, fractionation and/or concentration of materials. Microbial mineral precipitation is resulted from metabolic activities of microorganisms. Based on this biomineralogy concept, an attempt has been made to develop bioconcrete material incorporating of an enrichment culture of thermophilic and anaerobic bacteria within cement-sand mortar/concrete. The results showed a significant increase in compressive strength of both cement-sand mortar and concrete due to the development of filler material within the pores of cement sand matrix. Maximum strength was observed at concentration 10(5)cell/ml of water used in mortar/concrete. Addition of Escherichia coil or media composition on mortar showed no such improvement in strength.