Prevalence of Ewingella americana in retail fresh cultivated mushrooms (Agaricus bisporus, Lentinula edodes and Pleurotus ostreatus) in Zaragoza (Spain)

Antimicrobial Activity of Grapefruit Seed Extract on Edible Mushrooms Contaminations: Efficacy in Preventing Pseudomonas spp. in Pleurotus eryngii

Pleurotus eryngii is an edible mushroom that suffers significant losses due to fungal contamination and bacteriosis. The Pseudomonadaceae family represents one of the most frequent etiologic agents. Grapefruit seed extract (GSE) is a plant extract that contains different bioactive components, such as naringin, and exhibits a strong antibacterial and antioxidant activity. Over the last decade, GSE use as an alternative to chemical treatments in the food sector has been tested. However, to our knowledge, its application on mushroom crops has never been investigated. This study focuses on evaluating GSE efficacy in preventing P. eryngii yellowing. GSE antibiotic activity, inhibitory and bactericidal concentrations, and antibiofilm activity against several microorganisms were tested with the Kirby-Bauer disk diffusion assay, the broth microdilution susceptibility test, and the Crystal violet assay, respectively. In vitro, the extract exhibited antimicrobial and antibiofilm activity against Staphylococcus aureus 6538 and MRSA (wild type), Escherichia coli ATCC 8739, and Pseudomonas spp. (Pseudomonas aeruginosa 9027, P. fluorescens (wild type)). GSE application in vivo, in pre- and post-sprouting stages, effectively prevented bacterial infections and subsequent degradation in the mushroom crops: none of the P. eryngii treated manifested bacteriosis. Our findings support the use of GSE as an eco-friendly and sustainable alternative to chemical treatments for protecting P. eryngii crops from bacterial contamination, consequently ensuring food safety and preventing financial losses due to spoilage. Furthermore, GSE's potential health benefits due to its content in naringin and other bioactive components present new possibilities for its use as a nutraceutical in food fortification and supplementation.

Bacterial community dynamics and metabolic functions prediction in white button mushroom (Agaricus bisporus) during storage

White button mushroom (Agaricus bisporus) is rich in nutritional value, but it is easily infected by microorganisms during storage, which leads to spoilage and shortens the storage time. In this paper, A. bisporus at different storage times was sequenced by Illumina Novaseq 6000 platform. QIIME2 and PICRUSt2 were used to analyze the changes of bacterial community diversity and predict metabolic functions during storage of A. bisporus. Then, the pathogenic bacteria were isolated and identified from the spoilt samples of A. bisporus with black spot. The results showed that the bacterial species richness of A. bisporus surface gradually decreased. 2,291 ASVs were finally obtained through DADA2 denoising, belonging to 27 phyla, 60 classes, 154 orders, 255 families and 484 genera. The abundance of Pseudomonas on the surface of fresh A. bisporus sample was 22.8%, which increased to 68.7% after 6 days of storage. The abundance significantly increased and became a dominant spoilage bacterium. In addition, A total of 46 secondary metabolic pathways belonging to 6 categories of primary biological metabolic pathways were predicted during storage of A. bisporus, and metabolism (71.8%) was the main functional pathway. Co-occurrence network analysis revealed that the dominant bacterium Pseudomonas was positively correlated with 13 functional pathways (level 3). A total of 5 strains were isolated and purified from diseased A. bisporus surface. The test of pathogenicity showed that Pseudomonas tolaasii caused serious spoilage of A. bisporus. The study provided a theoretical basis for the development of antibacterial materials to reduce related diseases and prolong the storage time of A. bisporus.

Growth performance of Listeria monocytogenes and background microbiota from mushroom processing environments

Interaction between Listeria monocytogenes and resident background microbiota may occur in food processing environments and may influence the survival of this pathogen in a factory environment. Therefore the aim of this study was to characterize the growth performance of microbiota isolated from the processing environments of frozen sliced mushrooms, and to investigate the competitive performance of L. monocytogenes when co-cultured with accompanying environmental microbiota. Acinetobacter, Enterobacteriaceae, Lactococcus and Pseudomonas were the most prominent background microbiota isolated from the processing environment of frozen sliced mushrooms. All individual microbiota strains were able to grow and form biofilm in filter-sterilized mushroom medium, with the mannitol-consumers Raoultella and Ewingella as top performers, reaching up to 9.6 and 9.8 log CFU/mL after 48 h incubation at room temperature. When L. monocytogenes mushroom isolates were co-cultured with the microbiota strains, L. monocytogenes counts ranged from 7.6 to 8.9 log CFU/mL after 24 h of incubation, while counts of the microbiota strains ranged from 5.5 to 9.0 log CFU/mL. Prolonged incubation up to 48 h resulted in further increase of L. monocytogenes counts when co-cultured with non-acidifying species Pseudomonas and Acinetobacter reaching 9.1 to 9.2 log CFU/mL, while a decrease of L. monocytogenes counts reaching 5.8 to 7.7 log CFU/mL was observed in co-culture with Enterobacteriaceae and acidifying Lactococcus representatives. In addition, L. monocytogenes grew also in spent mushroom media of the microbiota strains, except in acidified spent media of Lactococcus strains. These results highlight the competitive ability of L. monocytogenes during co-incubation with microbiota in fresh and in spent mushroom medium, indicative of its invasion and persistence capacity in food processing factory environments.

Variability in growth and biofilm formation of Listeria monocytogenes in Agaricus bisporus mushroom products

Foods and food production environments can be contaminated with Listeria monocytogenes and may support growth of this foodborne pathogen. This study aims to characterize the growth and biofilm formation of sixteen L. monocytogenes strains, isolated from mushroom production and processing environments, in filter-sterilized mushroom medium. Strain performance was compared to twelve L. monocytogenes strains isolated from other sources including food and human isolates. All twenty-eight L. monocytogenes strains showed rather similar growth performance at 20 °C in mushroom medium, and also significant biofilm formation was observed for all strains. HPLC analysis revealed the presence of mannitol, trehalose, glucose, fructose and glycerol, that were all metabolized by L. monocytogenes, except mannitol, in line with the inability of L. monocytogenes to metabolize this carbohydrate. Additionally, the growing behavior of L. monocytogenes was tested on whole, sliced and smashed mushroom products to quantify performance in the presence of product-associated microbiota. A significant increase of L. monocytogenes was observed with higher increase of counts when the mushroom products were more damaged, even with the presence of high background microbiota counts. This study demonstrated that L. monocytogenes grows well in mushroom products, even when the background microbiota is high, highlighting the importance to control (re)contamination of mushrooms.

Ewingella americana: An Emerging Multifaceted Pathogen of Edible Mushrooms

Mycopathogenic bacteria play a pivotal role in the productivity of edible mushrooms grown under controlled conditions. In this study, we carried out a comprehensive farm survey and sampling (2018 to 2021) on button mushroom (Agaricus bisporus) farms in 15 provinces in Iran to monitor the status of bacterial pathogens infecting the crop. Mycopathogenic bacterial strains were isolated from pins, stems, and caps, as well as the casing layer on 38 mushroom farms. The bacterial strains incited symptoms on mushroom caps ranging from faint discoloration to dark brown and blotch of the inoculated surfaces. Among the bacterial strains inciting disease symptoms on bottom mushroom, 40 were identified as Ewingella americana based on biochemical assays and phylogeny of 16S rRNA and the gyrB gene. E. americana strains differed in their aggressiveness on mushroom caps and stipes, where the corresponding symptoms ranged from deep yellow to dark brown. In the phylogenetic analyses, all E. americana strains isolated in this study were clustered in a monophyletic clade closely related to the nonpathogenic and environmental strains of the species. BOX-PCR-based fingerprinting revealed intraspecific diversity. Using the cutoff level of 73 to 76% similarity, the strains formed six clusters. A chronological pattern was observed, where the strains isolated in 2018 were differentiated from those isolated in 2020 and 2021. Taken together, due to the multifaceted nature of the pathogen, such a widespread occurrence of E. americana on mushroom farms in Iran could be an emerging threat for the mushroom industry in the country.

Pleurotus ostreatus Grown on Agro-Industrial Residues: Studies on Microbial Contamination and Shelf-Life Prediction under Different Packaging Types and Storage Temperatures

The short shelf-life of mushrooms, due to water loss and microbial spoilage, is the main constraint for commercialization and consumption. The effect of substrate type combined with different temperatures and packaging conditions on the shelf-life of fresh Pleurotus ostreatus is scantily researched. The current study investigated the shelf-life of fresh oyster mushrooms grown on low (0.3, 0.3, 0.17) and high (0.7, 0.7, 0.33) rates of olive pruning residues (OLPR), spent coffee grounds (SCG), and both combined residues (OLPR/SCG) with wheat straw (WS), respectively, at ambient (20 °C) and 4 °C temperatures under no packaging, polyethylene plastic bag packaging (PBP), and polypropylene vacuum bag packaging (VBP). Results showed that at ambient temperature OLPR/SCG mushrooms PBP-bagged had an increased shelf-life by 0.5-1.2 days in comparison with WS ones. The predictive models adopted to optimize mushroom shelf-life at ambient temperature set rates of 0.289 and 0.303 of OLPR and OLPR/SCG, respectively, and PBP as the most suitable conditions (9.18 and 9.14 days, respectively). At 4 °C, OLPR/SCG mushrooms VBP-bagged had a longer shelf-life of 2.6-4.4 days compared to WS ones. Predictive models noted a maximized shelf-life of VBP-bagged mushrooms (26.26 days) when a rate of 0.22 OLPR/SCG is incorporated into the initial substrate. The combination of OLPR and SCG increased the shelf-life of fresh Pleurotus ostreatus by decreasing the total microbial count (TMC) while delaying weight loss and veil opening, and maintaining carbohydrate content, good firmness, and considerable protein, in comparison with WS regardless the storage temperature and packaging type.

Characterization, Pathogenicity, Phylogeny, and Comparative Genomic Analysis of Pseudomonas tolaasii Strains Isolated from Various Mushrooms in China

Since 2016, devastating bacterial blotch affecting the fruiting bodies of Agaricus bisporus, Cordyceps militaris, Flammulina filiformis, and Pleurotus ostreatus in China has caused severe economic losses. We isolated 102 bacterial strains and characterized them polyphasically. We identified the causal agent as Pseudomonas tolaasii and confirmed the pathogenicity of the strains. A host range test further confirmed the pathogen's ability to infect multiple hosts. This is the first report in China of bacterial blotch in C. militaris caused by P. tolaasii. Whole-genome sequences were generated for three strains: Pt11 (6.48 Mb), Pt51 (6.63 Mb), and Pt53 (6.80 Mb), and pangenome analysis was performed with 13 other publicly accessible P. tolaasii genomes to determine their genetic diversity, virulence, antibiotic resistance, and mobile genetic elements. The pangenome of P. tolaasii is open, and many more gene families are likely to emerge with further genome sequencing. Multilocus sequence analysis using the sequences of four common housekeeping genes (glns, gyrB, rpoB, and rpoD) showed high genetic variability among the P. tolaasii strains, with 115 strains clustered into a monophyletic group. The P. tolaasii strains possess various genes for secretion systems, virulence factors, carbohydrate-active enzymes, toxins, secondary metabolites, and antimicrobial resistance genes that are associated with pathogenesis and adapted to different environments. The myriad of insertion sequences, integrons, prophages, and genome islands encoded in the strains may contribute to genome plasticity, virulence, and antibiotic resistance. These findings advance understanding of the determinants of virulence, which can be targeted for the effective control of bacterial blotch disease.

Microbiological Safety and Sensory Quality of Cultivated Mushrooms (Pleurotus eryngii, Pleurotus ostreatus and Lentinula edodes) at Retail Level and Post-Retail Storage

In this study, the microbiological and sensory quality of cultivated mushrooms (Pleurotus ostreatus and eryngii and Lentinula edodes) available at the Austrian retail level were determined. Aerobic mesophilic bacteria (AMC), Enterobacteriaceae (EB), Pseudomonadaceae (PS), lactic acid bacteria (LAB), yeast, moulds and presumptive Bacillus cereus were enumerated at the day of purchase and after storage at 4 °C for 7 or 12 days. Additionally, the presence of Salmonella spp. and Listeria monocytogenes was investigated. Isolates of presumptive spoilage bacteria were confirmed by partial 16S rRNA sequencing. At the day of purchase, 71.2% of the samples were of high microbiological quality and grouped into the low contamination category (AMC < 5.0 log cfu/g), while the sensory quality of 67.1% was categorized as “very good or good”. After storage, the number of samples with high microbial quality was 46.6%, and only 37.0% of the samples scored as “very good or good”. The most abundant species across all mushroom samples were the Pseudomonas fluorescens species complex (58.4%) and the potential mushroom pathogen Ewingella americana (28.3%). All mushroom samples tested negative for Salmonella spp., L. monocytogenes and Bacillus cereus. The microbiological and sensory quality of the analysed mushrooms at the day of purchase and after storage was considered to be good overall. Longer transport distances were found to have a significant influence on the microbiological and sensory quality.

Feeding on fungi: genomic and proteomic analysis of the enzymatic machinery of bacteria decomposing fungal biomass

Dead fungal biomass is an abundant source of nutrition in both litter and soil of temperate forests largely decomposed by bacteria. Here, we have examined the utilization of dead fungal biomass by the five dominant bacteria isolated from the in situ decomposition of fungal mycelia using a multiOMIC approach. The genomes of the isolates encoded a broad suite of carbohydrate-active enzymes, peptidases and transporters. In the extracellular proteome, only Ewingella americana expressed chitinases while the two Pseudomonas isolates attacked chitin by lytic chitin monooxygenase, deacetylation and deamination. Variovorax sp. expressed enzymes acting on the side-chains of various glucans and the chitin backbone. Surprisingly, despite its genomic potential, Pedobacter sp. did not produce extracellular proteins to decompose fungal mycelia but presumably feeds on simple substrates. The ecological roles of the five individual strains exhibited complementary features for a fast and efficient decomposition of dead fungal biomass by the entire bacterial community.

Molecular characterization of Pseudomonas from Agaricus bisporus caps reveal novel blotch pathogens in Western Europe

Background

Bacterial blotch is a group of economically important diseases affecting the cultivation of common button mushroom, Agaricus bisporus. Despite being studied for more than a century, the identity and nomenclature of blotch-causing Pseudomonas species is still unclear. This study aims to molecularly characterize the phylogenetic and phenotypic diversity of blotch pathogens in Western Europe.

Methods

In this study, blotched mushrooms were sampled from farms across the Netherlands, United Kingdom and Belgium. Bacteria were isolated from symptomatic cap tissue and tested in pathogenicity assays on fresh caps and in pots. Whole genome sequences of pathogenic and non-pathogenic isolates were used to establish phylogeny via multi-locus sequence alignment (MLSA), average nucleotide identity (ANI) and in-silico DNA:DNA hybridization (DDH) analyses.

Results

The known pathogens “Pseudomonas gingeri”, P. tolaasii, “P. reactans” and P. costantinii were recovered from blotched mushroom caps. Seven novel pathogens were also identified, namely, P. yamanorum, P. edaphica, P. salomonii and strains that clustered with Pseudomonas sp. NC02 in one genomic species, and three non-pseudomonads, i.e. Serratia liquefaciens, S. proteamaculans and a Pantoea sp. Insights on the pathogenicity and symptom severity of these blotch pathogens were also generated.

Conclusion

A detailed overview of genetic and regional diversity and the virulence of blotch pathogens in Western Europe, was obtained via the phylogenetic and phenotypic analyses. This information has implications in the study of symptomatic disease expression, development of diagnostic tools and design of localized strategies for disease management.

Comparative Genomic Analysis Provides Insights into the Phylogeny, Resistome, Virulome, and Host Adaptation in the Genus Ewingella

Ewingella americana is a cosmopolitan bacterial pathogen that has been isolated from many hosts. Here, we sequenced a high-quality genome of E. americana B6-1 isolated from Flammulina filiformis, an important cultivated mushroom, performed a comparative genomic analysis with four other E. americana strains from various origins, and tested the susceptibility of B6-1 to antibiotics. The genome size, predicted genes, and GC (guanine-cytosine) content of B6-1 was 4.67 Mb, 4301, and 53.80%, respectively. The origin of the strains did not significantly affect the phylogeny, but mobile genetic elements shaped the evolution of the genus Ewingella. The strains encoded a set of common genes for type secretion, virulence effectors, CAZymes, and toxins required for pathogenicity in all hosts. They also had antibiotic resistance, pigments to suppress or evade host defense responses, as well as genes for adaptation to different environmental conditions, including temperature, oxidation, and nutrients. These findings provide a better understanding of the virulence, antibiotic resistance, and host adaptation strategies of Ewingella, and they also contribute to the development of effective control strategies.

Predictive modelling for the growth kinetics of Pseudomonas spp. on button mushroom (Agaricus bisporus) under isothermal and non-isothermal conditions

Baranyi model was fitted to experimental growth data of Pseudomonas spp. on the button mushrooms (Agaricus bisporus) stored at different isothermal conditions (4, 12, 20 and 28 °C), and the kinetic growth parameters of Pseudomonas spp. on the button mushrooms were obtained. The goodness of fit of the Baranyi model was evaluated by considering the root mean squared error (RMSE) and the adjusted coefficient of determination (adjusted-R²). The Baranyi model gave RMSE values lower than 0.193 and adjusted-R² values higher than 0.975 for all isothermal storage temperatures. The maximum specific growth rate (µ_max) was described as a function of temperature using secondary models namely, Ratkowsky and Arrhenius models. The Ratkowsky model described the temperature dependence of µ_max better than the Arrhenius model. Therefore, the differential form of the Baranyi model was merged with the Ratkowsky model, and solved numerically using the fourth-order Runge-Kutta method to predict the concentration of Pseudomonas spp. populations on button mushrooms under non-isothermal conditions in which they are frequently subjected to during storage, delivery and retail marketing. The validation performance of the dynamic model used was assessed by considering bias (B_f) and accuracy (A_f) factors which were found to be 0.998 and 1.016, respectively. The dynamic model developed also exhibited quite small mean deviation (MD) and mean absolute deviation (MAD) values being -0.013 and 0.126 log CFU/g, respectively. The modelling approach used in this work could be an alternative to traditional enumeration techniques to determine the number of Pseudomonas spp. on mushrooms as a function of temperature and time.

100 Years Since Tolaas: Bacterial Blotch of Mushrooms in the 21st Century

Among the biotic constraints of common mushroom (Agaricus bisporus) production, bacterial blotch is considered the most important mushroom disease in terms of global prevalence and economic impact. Etiology and management of bacterial blotch has been a major concern since its original description in 1915. Although Pseudomonas tolaasii is thought to be the main causal agent, various Pseudomonas species, as well as organisms from other genera have been reported to cause blotch symptoms on mushroom caps. In this review, we provide an updated overview on the etiology, epidemiology, and management strategies of bacterial blotch disease. First, diversity of the causal agent(s) and utility of high throughput sequencing-based approaches in the precise characterization and identification of blotch pathogen(s) is explained. Further, due to the limited options for use of conventional pesticides in mushroom farms against blotch pathogen(s), we highlight the role of balanced threshold of relative humidity and temperature in mushroom farms to combat the disease in organic and conventional production. Additionally, we discuss the possibility of the use of biological control agents (either antagonistic mushroom-associated bacterial strains or bacteriophages) for blotch management as one of the sustainable approaches for 21^st century agriculture. Finally, we aim to elucidate the association of mushroom microbiome in cap development and productivity on one hand, and blotch incidence/outbreaks on the other hand.

Microflora of fresh white button mushrooms (Agaricus bisporus) during cold storage revealed by high-throughput sequencing and MALDI-TOF mass spectrometry fingerprinting

BACKGROUND

Fresh Agaricus bisporus is popular and consumed throughout the world because of its taste, as well as its nutritional and medicinal properties, but it is also prone to microbial growth. There is very limited information about the dynamic changes of microbial communities during storage. The present study aimed to analyze the microbial diversity of button mushroom during cold storage using Illumina HiSeq sequencing. Bacteria isolated from the later storage period were identified by MALDI-TOF mass spectrometry and a bioassay of pathogenicity was carried out.

RESULTS

High-throughput sequencing showed that Pseudomonas was the predominant genus throughout the storage period. Pedobacter and Flavobacterium grew prolifically on the eighth day, while the relative abundance of Oscillospira continued to decrease. Pseudomonas, Ewingella and Chryseobacterium were isolated at the later period of mushroom storage. A pathogenicity bioassay on the cap of mushrooms showing brown blotch indicated an infection by Pseudomonas tolaasii. However, Ewingella americana did not have a pathogenic effect in our study.

CONCLUSION

Bacterial communities of fresh Agaricus bisporus during cold storage were characterized by high-throughput sequencing. MALDI-TOF MS provides a good analytical procedure, in addition to 16S rRNA gene sequencing. © 2019 Society of Chemical Industry.

Compost bacteria and fungi that influence growth and development of Agaricus bisporus and other commercial mushrooms

Mushrooms are an important food crop for many millions of people worldwide. The most important edible mushroom is the button mushroom (Agaricus bisporus), an excellent example of sustainable food production which is cultivated on a selective compost produced from recycled agricultural waste products. A diverse population of bacteria and fungi are involved throughout the production of Agaricus. A range of successional taxa convert the wheat straw into compost in the thermophilic composting process. These initially break down readily accessible compounds and release ammonia, and then assimilate cellulose and hemicellulose into compost microbial biomass that forms the primary source of nutrition for the Agaricus mycelium. This key process in composting is performed by a microbial consortium consisting of the thermophilic fungus Mycothermus thermophilus (Scytalidium thermophilum) and a range of thermophilic proteobacteria and actinobacteria, many of which have only recently been identified. Certain bacterial taxa have been shown to promote elongation of the Agaricus hyphae, and bacterial activity is required to induce production of the mushroom fruiting bodies during cropping. Attempts to isolate mushroom growth-promoting bacteria for commercial mushroom production have not yet been successful. Compost bacteria and fungi also cause economically important losses in the cropping process, causing a range of destructive diseases of mushroom hyphae and fruiting bodies. Recent advances in our understanding of the key bacteria and fungi in mushroom compost provide the potential to improve productivity of mushroom compost and to reduce the impact of crop disease.

Diseases and pests noxious to Pleurotus spp. mushroom crops

The Pleurotus genus is one of most extensively studied white-rot fungi due to its exceptional ligninolytic properties. It is an edible mushroom that possesses biological effects, as it contains important bioactive molecules. It is a rich source of nutrients, particularly proteins, minerals as well as vitamins B, C and D. In basidiomycete fungi, intensive cultivations of edible mushrooms can often be affected by some bacterial, mold and virus diseases that rather frequently cause dramatic production loss. These infections are facilitated by the particular conditions under which mushroom cultivation is commonly carried out such as warm temperatures, humidity, carbon dioxide (CO₂) levels and presence of pests. There is not much bibliographic information related to pests of mushrooms and their substrates. The updated review presents a practical checklist of diseases and pests of the Pleurotus genus, providing useful information that may help different users.

Cultivable microbiome of fresh white button mushrooms

Microbial dynamics on commercially grown white button mushrooms is of importance in terms of food safety assurance and quality control. The purpose of this study was to establish the microbial profile of fresh white button mushrooms. The total microbial load was determined through standard viable counts. Presence and isolation of Gram-negative bacteria including coagulase-positive Staphylococci were performed using a selective enrichment approach. Dominant and presumptive organisms were confirmed using molecular methods. Total mushroom microbial counts ranged from 5·2 to 12·4 log CFU per g, with the genus Pseudomonas being most frequently isolated (45·37% of all isolations). In total, 91 different microbial species were isolated and identified using Matrix-assisted laser desorption ionization-time of flight mass spectrophotometry, PCR and sequencing. Considering current food safety guidelines in South Africa for ready-to-eat fresh produce, coliform counts exceeded the guidance specifications for fresh fruit and vegetables. Based on our research and similar studies, it is proposed that specifications for microbial loads on fresh, healthy mushrooms reflect a more natural microbiome at the point-of-harvest and point-of-sale.

SIGNIFICANCE AND IMPACT OF THE STUDY

Presence and persistence of micro-organisms within the microbiome of fresh produce is important when identifying a potential niche for foodborne pathogens. Most foodborne outbreaks can be attributed to microbial imbalances or lack of diversity within the associated host surface and residing microbial population. Agaricus bisporus samples analysed during this study showed a higher microbial load (5·2 up to 12·4 log CFU per g) compared to known values for other fresh produce. These mushrooms were considered to carry microbial loads representing a healthy and safe product, fit for consumption, despite showing a high indicator incidence. Although foodborne pathogens may be associated on occasion with fresh mushrooms, it remains a low-risk commodity; therefore, this study provides insight and experimental evidence identifying microbial population dynamics of fresh and packed mushrooms.

Avaliação de bactérias endofíticas para o controle biológico da mancha foliar de Exserohilum turcicum em milho

RESUMO:A eficácia de nove isolados de bactérias endofíticas foi avaliada no biocontrole da mancha foliar de Exserohilum turcicum, pela microbiolização das sementes e da parte aérea do milho híbrido AS-1548 (72 e 24 horas antes e no mesmo dia da inocula ção do patógeno) em condições de casa de vegetação. Verificou-se que Bacillus subtilis 0G, Bacillus lentimorbus, Streptomyces sp. e Bacillus agaradhaerens se destacaram dos demais, quando aplicados na parte aérea, em todos os intervalos testados, com um controle na ordem de 42 a 61%. Quando as bactérias foram aplicadas nas sementes, Bacillus lentimorbus, Streptomyces sp., Ewingella ameri cana e Xanthomonas axonopodis foram os mais eficientes, com um controle entre 37 e 59%.

Ewingella americana: an emerging true pathogen

Infections caused by Ewingella americana have been rarely reported in the literature. Most of the cases that have been reported were among the immunocompromised patients. We report a case of E. americana causing osteomyelitis and septic arthritis of the shoulder joint in a previous intravenous drug abuser. The causative pathogen was identified by synovial fluid analysis and culture.