Thermal Pyocyanin Sensor Based on Molecularly Imprinted Polymers for the Indirect Detection of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a ubiquitous multi-drug-resistant bacterium, capable of causing serious illnesses and infections. This research focuses on the development of a thermal sensor for the indirect detection of P. aeruginosa infection using molecularly imprinted polymers (MIPs). This was achieved by developing MIPs for the detection of pyocyanin, the main toxin secreted by P. aeruginosa. To this end, phenazine was used as a dummy template, evaluating several polymeric compositions to achieve a selective MIP for pyocyanin recognition. The sensitivity of the synthesized MIPs was investigated by UV-vis analysis, with the best composition having a maximum rebinding capacity of 30 µmol g-1 and an imprinting factor (IF) of 1.59. Subsequently, the MIP particles were immobilized onto planar aluminum chips using an adhesive layer, to perform thermal resistance measurements at clinically relevant concentrations of pyocyanin (1.4-9.8 µM), achieving a limit of detection (LoD) of 0.347 ± 0.027 µM. The selectivity of the sensor was also scrutinized by subjecting the receptor to potential interferents. Furthermore, the rebinding was demonstrated in King's A medium, highlighting the potential of the sensor for the indirect detection of P. aeruginosa in complex fluids. The research culminates in the demonstration of the MIP-based sensor's applicability for clinical diagnosis. To achieve this goal, an experiment was performed in which the sensor was exposed to pyocyanin-spiked saliva samples, achieving a limit of detection of 0.569 ± 0.063 µM and demonstrating that this technology is suitable to detect the presence of the toxin even at the very first stage of its production.

Bacteriological analysis based on disease severity and clinical characteristics in patients with deep neck space abscess.

BACKGROUND: Deep neck space abscess (DNSA) is a serious infection in the head and neck. Antibiotic therapy is an important treatment in patients with DNSA. However, the results of bacterial culture need at least 48 h, and the positive rate is only 30-50%, indicating that the use of empiric antibiotic treatment for most patients with DNSA should at least 48 h or even throughout the whole course of treatment. Thus, how to use empiric antibiotics has always been a problem for clinicians. This study analyzed the distribution of bacteria based on disease severity and clinical characteristics of DNSA patients, and provides bacteriological guidance for the empiric use of antibiotics. METHODS: We analyzed 433 patients with DNSA who were diagnosed and treated at nine medical centers in Guangdong Province between January 1, 2015, and December 31, 2020. A nomogram for disease severity (mild/severe) was constructed using least absolute shrinkage and selection operator-logistic regression analysis. Clinical characteristics for the Gram reaction of the strain were identified using multivariate analyses. RESULTS: 92 (21.2%) patients developed life-threatening complications. The nomogram for disease severity comprised of seven predictors. The area under the receiver operating characteristic curves of the nomogram in the training and validation cohorts were 0.951 and 0.931, respectively. In the mild cases, 43.2% (101/234) had positive culture results (49% for Gram-positive and 51% for Gram-negative strains). The positive rate of cultures in the patients with severe disease was 63% (58/92, 37.9% for Gram-positive, and 62.1% for Gram-negative strains). Diabetes mellitus was an independent predictor of Gram-negative strains in the mild disease group, whereas gas formation and trismus were independent predictors of Gram-positive strains in the severe disease group. The positivity rate of multidrug-resistant strains was higher in the severe disease group (12.1%) than in the mild disease group (1.0%) (P < 0.001). Metagenomic sequencing was helpful for the bacteriological diagnosis of DNSA by identifying anaerobic strains (83.3%). CONCLUSION: We established a DNSA clinical severity prediction model and found some predictors for the type of Gram-staining strains in different disease severity cases. These results can help clinicians in effectively choosing an empiric antibiotic treatment.

Self-assembled plasmonic nanoarrays for enhanced bacterial identification and discrimination.

The rapid and accurate bacterial testing is a critical step for the management of infectious diseases, but challenges remain largely due to a lack of advanced sensing tools. Here we report the development of highly plasmon-active, biofunctional nanoparticle arrays for simultaneous capture, identification, and differentiation of bacteria by surface-enhanced Raman scattering (SERS). The nanoarrays were facilely prepared through an electrostatic mechanism-controlled self-assembly of metallic nanoparticles at liquid-liquid interfaces, and exhibited high SERS sensitivity beyond femtomole, good reproducibility (relative standard deviation of 2.7%) and stability. Modification of the nanoarrays with concanavalin A allowed to effective capture of both Gram-positive and Gram-negative bacteria (bacterial-capture efficiency maintained beyond 50%) at bacterial concentrations ranging from 50 to 2000 CFU mL-1, as determined by the plate-counting method. Moreover, single-cell Raman fingerprinting and discrimination of eight different bacteria species with high signal-to-noise ratio, excellent spectral reproducibility, and a total assay time of 1.5 h was achieved under fairly mild conditions (24 µW, acquisition time: 1 s). Collectively, we believe that our biofunctionalized, SERS-based self-assembled nanoarrays have great potential to help in rapid and label-free bacterial diagnosis and phenotyping study.

Bacterial Respiration Used as a Proxy to Evaluate the Bacterial Load in Cooling Towers.

Evaporative cooling towers to dissipate excess process heat are essential installations in a variety of industries. The constantly moist environment enables substantial microbial growth, causing both operative challenges (e.g., biocorrosion) as well as health risks due to the potential aerosolization of pathogens. Currently, bacterial levels are monitored using rather slow and infrequent sampling and cultivation approaches. In this study, we describe the use of metabolic activity, namely oxygen respiration, as an alternative measure of bacterial load within cooling tower waters. This method is based on optical oxygen sensors that enable an accurate measurement of oxygen consumption within a closed volume. We show that oxygen consumption correlates with currently used cultivation-based methods (R2 = 0.9648). The limit of detection (LOD) for respiration-based bacterial quantification was found to be equal to 1.16 × 104 colony forming units (CFU)/mL. Contrary to the cultivation method, this approach enables faster assessment of the bacterial load with a measurement time of just 30 min compared to 48 h needed for cultivation-based measurements. Furthermore, this approach has the potential to be integrated and automated. Therefore, this method could contribute to more robust and reliable monitoring of bacterial contamination within cooling towers and subsequently increase operational stability and reduce health risks.

Gut microbiota translocation promotes autoimmune cholangitis.

Gut microbiota and bacterial translocation have been implicated as significant contributors to mucosal immune responses and tolerance; alteration of microbial molecules, termed pathogen-associated molecular patterns (PAMP) and bacterial translocation are associated with immune pathology. However, the mechanisms by which dysregulated gut microbiota promotes autoimmunity is unclear. We have taken advantage of a well-characterized murine model of primary biliary cholangitis, dnTGFßRII mice, and an additional unique construct, toll-like receptor 2 (TLR2)-deficient dnTGFßRII mice coined dnTGFßRIITLR2-/- mice to investigate the influences of gut microbiota on autoimmune cholangitis. Firstly, we report that dnTGFßRII mice manifest altered composition of gut microbiota and that alteration of this gut microbiota by administration of antibiotics significantly alleviates T-cell-mediated infiltration and bile duct damage. Second, toll-like receptor 2 (TLR2)-deficient dnTGFßRII mice demonstrate significant exacerbation of autoimmune cholangitis when their epithelial barrier integrity was disrupted. Further, TLR2-deficiency mediates downregulated expression of tight junction-associated protein ZO-1 leading to increased gut permeability and bacterial translocation from gut to liver; use of antibiotics reduces microbiota translocation to liver and also decreases biliary pathology. In conclusion, our data demonstrates the important role of gut microbiota and bacterial translocation in the pathogenesis of murine autoimmune cholangitis.

Análise de espécies bacterianas em telefones públicos do centro da cidade de Caruaru ­ PE / Analysis of bacterial species in public telephones in the city center of Caruaru ­ PE

Introdução: os aparelhos de telefones públicos representam importantes agentes disseminadores de infecções por se tratarem de objetos frequentemente manipulados por grande número de pessoas em trânsito das mais diversas regiões. Considerando que a pele humana contém uma microbiota típica e a manipulação de objetos pode propiciar o deslocamento de microrganismos, os aparelhos de telefone podem transmitir doenças através desses agentes. Objetivo: analisar a variedade de espécies bacterianas nos fones de ouvido dos aparelhos de telefones públicos localizados no centro da cidade de Caruaru-PE (Brasil). Metodologia: foram coletados esfregaços dos fones de ouvido, especificamente da região auricular, de 77 telefones públicos do centro da cidade de Caruaru. O material foi colhido com swab estéril e transportado em meio BHI ao Laboratório de Práticas da Saúde da Associação Caruaruense de Ensino Superior, onde foram realizadas cultura e identificação dos agentes bacterianos. Resultados: em todas as amostras foram encontradas bactérias, havendo um predomínio de Staphylococcus coagulase negativa (50,64%), seguido de Bacillus subtilis (27,27%), como também houve presença de Bacillus sp. (28,57), Staphylococcus aureus (18,18%), Enterococcus sp. (2,59), Streptococus do grupo viridans (1,29) e Streptococus sp. (1,29). Conclusão: Há grande diversidade de espécies bacterianas nos fones de ouvido dos telefones públicos do Centro de Caruaru.

Introduction: public telephones represent important dissemination agents because they are objects varied by large numbers of people in transit from the most diverse regions. Consider that a human skin contains a typical microbiota and a manipulation of objects can propitiate the displacement of microorganisms, telephone devices can transmit diseases through agents. Objective: To analyze a variety of bacterial species in the headsets of public telephone sets located in the city of Caruaru-PE (Brazil). Methods: Smears were collected from the earphones, specifically from the auricular region, from 77 public telephones in the city center of Caruaru. The material was collected with sterile swab and transported in BHI medium to the Laboratory of Health Practices of the Caruaruense Association of Higher Education, where culture and identification of bacterial agents were carried out. Results: Staphylococcus coagulase negative (50.64%), followed by Bacillus subtilis (27.27%), were also found in all samples, as well as the presence of Bacillus sp. (28,57), taphylococcus aureus (18.18%), Enterococcus sp. (2,59), Streptococus do grupo viridans (1,29) and Streptococus sp. (1,29). Conclusion: There is a great diversity of bacterial species in the headsets of the public telephones of the Center of Caruaru.

Related factors and bacteriological analysis of puerperal infection in pregnant women with scarred uterus / 国际检验医学杂志

Objective To investigate the risk factors and etiology of puerperal infection in pregnant women with scar uterus.Methods 276 cases of uterine scar pregnant women were prospectively collected in the hos-pital,according to the development of postpartum puerperal infection or not,all pregnant women were divided into an infection group(n=25)or a non infection group(control group)(n=251).The main clinical features between the two groups were compared and the risk factors of puerperal infection in pregnant women with u-terine scar were analyzed.Results Compared with the control group,the incidence of gestational <37 weeks, perilous placenta previa,postpartum hemorrhage,premature rupture of membranes,placental abruption,preg-nancy induced hypertension and the past history of vaginitis was significantly higher in the infection group,and the difference was statistically significant(P< 0.05).Multivariate logistics regression analysis showed that the risk factors of puerperal infection in pregnant women with scarred uterus included dangerous placenta pre-via,postpartum hemorrhage and placental abruption.Gram negative bacteria were more common,accounting for 72.00%,the most common gram negative bacteria were Escherichia coli(32.00%),the most common gram positive bacteria were Staphylococcus aureus(12.00%).Conclusion Dangerous placenta previa,post-partum hemorrhage and placental abruption are the risk factors of puerperal infection in pregnant women with uterine scar,and Gram negative bacteria are common pathogens.

The value of antibody-coated bacteria in tracheal aspirates for the diagnosis of ventilator-associated pneumonia: a case-control study / Utilidade da avaliação de bactérias revestidas por anticorpos em aspirados traqueais para o diagnóstico de pneumonia associada à ventilação mecânica: um estudo caso-controle

ABSTRACT Objective: Ventilator-associated pneumonia (VAP) is the leading type of hospital-acquired infection in ICU patients. The diagnosis of VAP is challenging, mostly due to limitations of the diagnostic methods available. The aim of this study was to determine whether antibody-coated bacteria (ACB) evaluation can improve the specificity of endotracheal aspirate (EA) culture in VAP diagnosis. Methods: We conducted a diagnostic case-control study, enrolling 45 patients undergoing mechanical ventilation. Samples of EA were obtained from patients with and without VAP (cases and controls, respectively), and we assessed the number of bacteria coated with FITC-conjugated monoclonal antibodies (IgA, IgM, or IgG) or an FITC-conjugated polyvalent antibody. Using immunofluorescence microscopy, we determined the proportion of ACB among a fixed number of 80 bacteria. Results: The median proportions of ACB were significantly higher among the cases (n = 22) than among the controls (n = 23)-IgA (60.6% vs. 22.5%), IgM (42.5% vs. 12.5%), IgG (50.6% vs. 17.5%), and polyvalent (75.6% vs. 33.8%)-p < 0.001 for all. The accuracy of the best cut-off points for VAP diagnosis regarding monoclonal and polyvalent ACBs was greater than 95.0% and 93.3%, respectively. Conclusions: The numbers of ACB in EA samples were higher among cases than among controls. Our findings indicate that evaluating ACB in EA is a promising tool to improve the specificity of VAP diagnosis. The technique could be cost-effective and therefore useful in low-resource settings, with the advantages of minimizing false-positive results and avoiding overtreatment.

RESUMO Objetivo: A pneumonia associada à ventilação mecânica (PAVM) é o principal tipo de infecção adquirida no ambiente hospitalar em pacientes em UTIs. O diagnóstico de PAVM é desafiador, principalmente devido a limitações dos métodos diagnósticos disponíveis. O objetivo deste estudo foi determinar se a avaliação de bactérias revestidas por anticorpos (BRA) pode melhorar a especificidade de culturas de aspirado traqueal (AT) no diagnóstico de PAVM. Métodos: Estudo diagnóstico caso-controle envolvendo 45 pacientes sob ventilação mecânica. Amostras de AT foram obtidas de pacientes com e sem PAVM (casos e controles, respectivamente), e verificamos o número de bactérias revestidas com anticorpos monoclonais conjugados com FITC (IgA, IgM ou IgG) ou anticorpo polivalente conjugado com FITC. Utilizando microscopia de imunofluorescência, foi determinada a proporção de BRA em um número fixo de 80 bactérias. Resultados: A mediana das proporções de BRA foi significativamente maior nos casos (n = 22) que nos controles (n = 23) - IgA (60,6% vs. 22,5%), IgM (42,5% vs. 12,5%), IgG (50,6% vs. 17,5%) e polivalente (75,6% vs. 33,8%) - p < 0,001 para todos. A acurácia dos melhores pontos de corte para o diagnostico de PAVM em relação aos BRA monoclonais e polivalentes foi > 95,0% e > 93,3%, respectivamente. Conclusões: O número de BRA em amostras de AT foi maior nos casos que nos controles. Nossos achados indicam que a avaliação de BRA no AT é uma ferramenta promissora para aumentar a especificidade do diagnóstico de PAVM. A técnica pode ser custo-efetiva e, portanto, útil em locais com poucos recursos, com as vantagens de minimizar resultados falso-positivos e evitar o tratamento excessivo.

Rapid and label-free detection and assessment of bacteria by terahertz time-domain spectroscopy.

Here we demonstrated the potential and applicability of terahertz (THz) spectroscopy to detect four commonly found bacteria in the infectious diseases. Besides the different spectral characteristics between bacterial species, THz absorption differences for living bacteria, dead bacteria and bacterial powder of the same species were also investigated. Our results revealed that small differences in water contents between bacterial cells account for distinct discrepancies of the absorption coefficients, which can be used for bacterial species identification. Furthermore, living and dead bacteria showed different absorption coefficients as a result of their different hydration levels, suggesting that THz spectroscopy can be used to rapidly assess the living state of bacteria under test. Our results clearly demonstrated the ability of THz spectroscopy for time-saving and label-free detection of bacteria with minimal sample preparation, potentially to be utilized for point-of-care tests in the near future. Schematic representation of bacterial detection by THz spectroscopy. Different bacteria have distinctive absorption coefficients as a result of their different water contents.

Water quality assessment of Kavvayi Lake of northern Kerala, India using CCME water quality index and biological water quality criteria.

Assessment of water quality status of 7 sites of Kavvayi Wetland in northern Kerala (India) was carried out. The physico-chemical, bacteriological and biological parameters were monitored during pre-monsoon, monsoon and post-monsoon seasons. Canadian Council of Ministers of the Environment (CCME) water quality index of the Kavvayi Lake samples ranged from 43.99-44.77; indicating that water quality was threatened or impaired. The poor water quality status might be due to dumping of wastes from municipal and domestic sources and agricultural runoff. Biological water quality criteria (BWQC) determined for wetland revealed that stations such as mixing point of Kariangode River into Kavvayi Lake and Kottikkadavu was moderately polluted in pre-monsoon and post- monsoon seasons. Mixing point of Nileswar River into Kavvayi Lake was moderately polluted in pre-monsoon season. Both calculated indices suggest that quality of lake was found to be influenced by anthropogenic activities such as unscientific tourism and infrastructure development, land encroachment, sand mining, pollution etc. The study was carried out as part of a programme, which aimed to conserve Kavvayi wetland because of its unique ecological and environmental characteristics.

Identification of pathgenic bacteria in aqueous and vitreous of endophthalmitis by 16S rDNA sequencing technique / 中华实验眼科杂志

Background Endophthalmitis is a serious complication of intraocular surgery.Conventional identification methods for bacteria are becterial culture and smear method,but these laboratory tests spend a long time and have low positive rates.16S rDNA is the bacterial chromosome encoding ribosomal RNA sequences,and it is determined that 16S rDNA sequencing has a high specificity for the identification of bacteria.Objective This study was to identify the infectious bacteria from aqueous humor or vitreous body in the eyes with endophthalmitis by 16S rDNA sequencing technique,and to investigate the diagnosis efficency of 16S rDNA sequencing technique on bacterial endophthalmitis.Methods Anterior chamber fluid (0.1-0.2 ml) or vitreous humor (0.5-1.0 ml) specimens were collected from 5 eyes of 5 patients with endophthalmitis in Qingdao Eye Hospital from June to December 2015 and used for high throughput sequencing,bacterial culture and smear,respectively.Bacteria DNA was extracted from the specimen with D3096-01 trace DNA kit for the amplification of V3-V4 region of 16S rRNA gene and sequencing of hypervariable region of all microbes in the samples by MiSeq Illumina Sequencing Platform.Then the bioinformatic analysis including analysis of taxonomy,abundance and alpha diversity were performed.Nucleasefree water of 50 μl in the centrifuge tube was used as control.Results Five aqueous humor or vitreous body samples were collected,and the positive results were exhibited by smear examination,with the Gram positive bacilli in the trumatic endophthalmitis eye and Gram negative bacilli in the filtering bleb infectious endophthalmitis eye,and all culture results were negative.16S rDNA squencing showed the positive outcomes in all the 5 samples.The high abundent nacteral genuses were Staphylococcus (65.28％),Streptococcus (18.90％) and Pseudomonas (12.76％) in the trumatic endophthalmitis eye;the major components of sample were Pseudomonas (53.68％),Acinetobacter (8.62％) and Limnobacter (5.96％) in the eye with acute endophthalmitis occurring at 2 days following cataract surgery;the major components in the filtering bleb infectious endophthalmitis eye were Moraxella (88.89％) and Pseudomonas (9.52％);the Pseudomonas was major components in the later-onset endophthalmitis eye (84.63％) and the eye with acute endophthalmitis occurring at 1 day after cataract surgery (97.89％).Conclusions A distinct advantage is found in 16S rDNA sequencing technique for the indentification of the pathogenic bacteria in endophthalmitis eyes due to its high positive rate in comparison with bacterial culture and smear method.

Infective endocarditis caused by Neisseria elongata on a native tricuspid valve and confirmed by DNA sequencing.

Neisseria elongata, a common oral bacterium, has been recognized as a cause of infections such as infective endocarditis, septicemia, and osteomyelitis. Neisseria-induced infective endocarditis, although infrequently reported, typically arises after dental procedures. Without antibiotic therapy, its complications can be severe. We report the case of a 27-year-old man who presented with fever, severe dyspnea, and a leg abscess from cellulitis. An echocardiogram showed a vegetation-like echogenic structure on the septal leaflet of the patient's native tricuspid valve, and an insignificant Gerbode defect. Three blood cultures grew gram-negative, antibiotic-susceptible coccobacilli that were confirmed to be N. elongata. Subsequent DNA sequencing conclusively isolated N. elongata subsp nitroreducens as the organism responsible for the infective endocarditis. The patient recovered after 21 days of antibiotic therapy. In addition to the patient's unusual case, we discuss the nature and isolation of N. elongata and its subspecies.

The relationship between compost bedded pack performance, management, and bacterial counts.

The objective of this study was to assess the relationships among temperature, moisture, carbon-to-nitrogen (C:N) ratio, space per cow, and bacterial counts from bedding material collected from compost bedded pack (CBP) barns. A field survey of 42 routinely aerated CBP barns was conducted in Kentucky between October 2010 and March 2011. Two bedding material samples of 1,064.7 cm(3) each were collected during a single site visit from 9 evenly distributed locations throughout each barn and thoroughly mixed to create a composite sample representative of the entire CBP. Bacterial counts were determined for coliforms, Escherichia coli, streptococci, staphylococci, and Bacillus spp. University of Kentucky Regulatory Services (Lexington) laboratory personnel performed nutrient analyses to determine moisture, carbon, and nitrogen contents. Surface and 10.2-cm pack depth temperatures were collected for each of the 9 evenly distributed locations and the mean calculated to produce a composite temperature. Space per cow was calculated as the total CBP area divided by number of cows housed on the CBP. The GLM procedure of SAS (SAS Institute Inc., Cary, NC) generated models to describe factors affecting bacterial counts. Bacterial counts were 6.3 ± 0.6, 6.0 ± 0.6, 7.2 ± 0.7, 7.9 ± 0.5, and 7.6 ± 0.5 log 10 cfu/g of dry matter for coliform, Escherichia coli, streptococci, staphylococci, and Bacillus spp., respectively. Composite temperature, CBP moisture, C:N ratio, and space per cow had no effect on coliform counts. Escherichia coli reached a peak concentration when the C:N ratio was between 30:1 and 35:1. Staphylococci counts increased as ambient temperature increased. Streptococci counts decreased with increased space per cow and composite temperature and increased with increasing ambient temperature and moisture. Streptococci counts peaked at a C:N ratio ranging from 16:1 to 18:1. Bacillus spp. counts were reduced with increasing moisture, C:N ratio, and ambient temperature. Mastitis-causing bacteria thrive in similar conditions to that of composting bacteria and microbes, making elimination of these at higher temperatures (55 to 65°C) difficult in an active composting environment. Producers must use recommended milking procedures and other preventative practices to maintain low somatic cell count in herds with a CBP barn.

The communities of tomato (Solanum lycopersicum L.) leaf endophytic bacteria, analyzed by 16S-ribosomal RNA gene pyrosequencing.

Endophytic bacterial communities of tomato leaves were analyzed by 16S-rRNA gene pyrosequencing and compared to rhizosphere communities. Leaf endophytes mainly comprised five phyla, among which Proteobacteria was the most represented (90%), followed by Actinobacteria (1,5%), Planctomycetes (1,4%), Verrucomicrobia (1,1%), and Acidobacteria (0,5%). Gammaproteobacteria was the most abundant class of Proteobacteria (84%), while Alphaproteobacteria and Betaproteobacteria represented 12% and 4% of this phylum, respectively. Rarefaction curves for endophytic bacteria saturated at 80 OTUs, indicating a lower diversity as compared to rhizosphere samples (> 1700 OTUs). Hierarchical clustering also revealed that leaf endophytic communities strongly differed from rhizospheric ones. Some OTUs assigned to Bacillus, Stenotrophomonas, and Acinetobacter, as well as some unclassified Enterobacteriaceae were specific for the endophytic community, probably representing bacteria specialized in colonizing this niche. On the other hand, some OTUs detected in the leaf endophytic community were also present in the rhizosphere, probably representing soil bacteria that endophytically colonize leaves. As a whole, this study describes the composition of the endophytic bacterial communities of tomato leaves, identifying a variety of genera that could exert multiple effects on growth and health of tomato plants.

Propriedades físico-químicas, sensoriais e bacteriológicas de camarões (Litopenaeus brasiliensis) irradiados e armazenados sob refrigeração / Physical, chemical, sensorial and bacterial properties of irradiated shrimp (Litopenaeus brasiliensis) stored under refrigeration

A irradiação de alimentos é uma opção tecnológica para minimizar problemas de perdas de alimentos, pois reduz asalterações provenientes da atividade bacteriana, estendendo a validade do produto. Neste estudo foram irradiados camarões(Litopenaeus brasiliensis) com doses de 1,5 e 2,5 kGy, após 30 dias de armazenamento sob refrigeração (2°C ± 2°C), como objetivo de avaliar os efeitos da irradiação sobre a validade comercial de camarões através de parâmetros físico-químicos,microbiológicos e sensoriais. Foram avaliados pH, bases voláteis totais (BVT), contagem de bactérias heterotróficas aeróbiasmesófilas (BHAM) e heterotróficas aeróbias psicrófilas (BHAP) e teste de aceitação sensorial. Os valores de pH não variaramentre as amostras controle e as amostras irradiadas apresentando média de 7,08 ± 0,21 durante os 30 dias de armazenamento.A produção de BVT nas amostras controle extrapolou o limite aceitável para o consumo no 15o dia de armazenamentoenquanto nas amostras irradiadas com 2,5 kGy, este limite não foi alcançado em 28 dias de armazenamento, demonstrandoo efeito positivo da utilização da irradiação. Na análise sensorial, não ocorreu diferença significativa (p> 0,01) na aceitação,quanto aos atributos de sabor, aparência, aroma e impressão global entre as amostras.

Food irradiation is currently regarded as a technological option to mitigate food losses due to its potential in reducing microbiological load and its associated spoilage effects, consequently extending the shelf life of many products. Samples of shrimp (Litopenaeus brasiliensis) have been exposed to gamma doses of 0, 1.5 and 2.5 kGy and monitored changes in sensorial characteristics (30 judges), pH and total volatile bases (TVB) levels. All samples were kept at 2°C ± 2°C through the experiments. No significant change in pH has been observed during the experiments regardless of the gamma dose applied. There was statistical difference between the non-irradiated samples and those irradiated with 2.5 kGy (p 0.01), though no significant difference has been found between the non-irradiated samples and those irradiated with 1.5 kGy nor between the samples irradiated with 1.5 kGy and those irradiated with 2.5 kGy. Based on the upper commercial limit for NB, non-irradiated samples achieved the limit in 15 days while the samples irradiated with 2.5 kGy didnt achieve the limit in 28 days. In sensorial analyses, there was no significant difference (p> 0.01) in the acceptance, according to the attributes flavor, appearance, aroma and global impression among the samples.