Exploiting tropical fruit processing coproducts as circular resources to promote the growth and maintain the culturability and functionality of probiotic lactobacilli.

This study evaluated the use of acerola (Malpighia glabra L., CACE), cashew (Anacardium occidentale L., CCAS), and guava (Psidium guayaba L., CGUA) fruit processing coproducts as substrates to promote the growth, metabolite production, and maintenance of the viability/metabolic activity of the probiotics Lactobacillus acidophilus LA-05 and Lacticaseibacillus paracasei L-10 during cultivation, freeze-drying, storage, and exposure to simulated gastrointestinal digestion. Probiotic lactobacilli presented high viable counts (≥8.8 log colony-forming units (CFU)/mL) and a short lag phase during 24 h of cultivation in CACE, CCAS, and CGUA. Cultivation of probiotic lactobacilli in fruit coproducts promoted sugar consumption, medium acidification, and production of organic acids over time, besides increasing the of several phenolic compounds and antioxidant activity. Probiotic lactobacilli cultivated in fruit coproducts had increased survival percentages after freeze-drying and during 120 days of refrigerated storage. Moreover, probiotic lactobacilli cultivated and freeze-dried in fruit coproducts had larger subpopulations of live and metabolically active cells when exposed to simulated gastrointestinal digestion. The results showed that fruit coproducts not only improved the growth and helped to maintain the viability and metabolic activity of probiotic strains but also enriched the final fermented products with bioactive compounds, being an innovative circular strategy for producing high-quality probiotic cultures.

Application of Potentially Probiotic Fruit-Derived Lactic Acid Bacteria Loaded into Sodium Alginate Coatings to Control Anthracnose Development in Guava and Mango During Storage.

This study evaluated the efficacy of potentially probiotic fruit-derived lactic acid bacteria (LAB) strains loaded into sodium alginate (SA) coatings to control the anthracnose development in guava cv. Paluma and mango cv. Palmer caused by distinct pathogenic Colletotrichum species (C. asianum, C. fructicola, C. tropicale, C. siamense, C. karstii, and C. gloeosporioides) during 15 days of room temperature storage (25 ± 0.5 °C). The effects of the formulated coatings on physicochemical parameters indicative of overall postharvest quality of guava and mango were evaluated. The eight examined LAB strains caused strong inhibition on the mycelial growth of all target Colletotrichum species in vitro. LAB strains with the highest inhibitory effects (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263) on the target Colletotrichum species were incorporated into SA coatings. These strains had viable counts of > 6 log CFU/mL in SA coatings during 15 days of room temperature storage. Application of coatings with SA + L. brevis 59, SA + L. pentosus 129, and SA + L. fermentum 263 delayed the development and decreased the severity of anthracnose lesions in guava and mango artificially contaminated with either of the tested Colletotrichum species. These coatings impacted positively on some physicochemical parameters indicative of postharvest quality and more prolonged storability of guava and mango. The formulated SA coatings loaded with tested fruit-derived potentially probiotic LAB strains could be innovative and effective strategies to control postharvest anthracnose and extend the storability of guava and mango.

Monocyclic Components and Photosynthetic Damage Caused by Myrtle Rust in Guava Leaves.

Austropuccinia psidii, the causal agent of myrtle rust, was, for many years, restricted to the Americas, but since reaching Hawaii in 2005, the pathogen has expanded its global range exponentially. In Brazil, myrtle rust is the main fungal disease in guava plants. Despite this, there are few studies on guava rust epidemiology. The objectives of this study were to quantify the monocyclic components of rust and to evaluate the photosynthetic damage caused by A. psidii in young and old leaves of 'Paluma' guava. The monocyclic components of guava rust and gas exchange in healthy or inoculated (105 ml-1 urediniospores of A. psidii) leaves were quantified over time. Additionally, young leaves were inoculated with varying concentrations of A. psidii inoculum, and leaf gas exchange and chlorophyll fluorescence were measured at 25 days postinoculation. The relationship between the relative CO2 assimilation of a diseased leaf (Px) and a healthy leaf (Po) is related to disease severity (x) by Px/Po = (1 - x)ß. The density of lesions, disease severity, and urediniospore production were high in young leaves, averaging 58 lesions cm-2, 50% leaf area diseased, and 2.5 × 104 urediniospores per lesion, respectively. Rust symptoms were not observed in old leaves, and resistance to infection did not cause any photosynthetic cost to these leaves. On young leaves, ß was 2.13, indicating a reduction on CO2 assimilation at green tissues from symptomatic leaves. Our data revealed that photosynthesis reduction in diseased guava leaves was caused by biochemical and photochemical damage rather than by stomatal limitation.

Arbuscular mycorrhizal fungi decrease Meloidogyne enterolobii infection of Guava seedlings.

Guava (Psidium guajava L.) production is prominent in the irrigated fruit growing area of Brazil. However, the parasite Meloidogyne enterolobii (a phytonematode) has caused a decrease in guava production. Arbuscular mycorrhizal fungi (AMF) are known to be beneficial to plants; however, their ability to protect plants against nematodes such as M. enterolobii remains poorly known. This study aimed to monitor M. enterolobii infection in guava seedlings inoculated with three AMF species. After AMF inoculation, the seedlings were grown in sterile soil for 60 days before inoculation with 2000 M. enterolobii eggs. Plant growth parameters, mycorrhizal colonization and the number of Meloidogyne in the roots were determined over time (30 and 60 days after Meloidogyne inoculation). The AMF enhanced guava seedling growth, and reduced the amount of Meloidogyne in the roots at 30 and 60 days after nematode inoculation, indicating that these AMF species could serve as biocontrol agents of M. enterolobii in guava cultivation.

Specific and sensitive detection of the guava fruit anthracnose pathogen (Colletotrichum gloeosporioides) by loop-mediated isothermal amplification (LAMP) assay.

Anthracnose of guava, caused by the fungus Colletotrichum gloeosporioides, is a major factor limiting worldwide guava production. Timely and accurate detection of the pathogen is important in developing a disease management strategy. Herein, a loop-mediated isothermal amplification (LAMP) assay for the specific and sensitive detection of C. gloeosporioides was developed using primers targeting the ß-tubulin 2 (TUB2) gene. The optimal reaction conditions were 64 °C for 60 min. The specificity of the method was tested against C. gloeosporioides isolates, Colletotrichum spp. isolates, and isolates of other genera. Positive results were obtained only in the presence of C. gloeosporioides, whereas no cross-reaction was observed for other species. The detection limit of the LAMP assay was 10 fg of genomic DNA in a 25 µL reaction. The LAMP assay successfully detected C. gloeosporioides in guava fruit collected in the field. The results indicate that the developed LAMP assay is a simple, cost-effective, rapid, highly sensitive, and specific tool for the diagnosis of guava anthracnose caused by C. gloeosporioides and could be useful for disease management.

Cytotoxic and neuroprotective activities of constituents from Alternaria alternate, a fungal endophyte of Psidium littorale.

Chemical investigation of the EtOAc extract of the plant-associated fungus Alternaria alternate in rice culture led to the isolation of a novel liphatic polyketone, alternin A (1), a new indole alkaloid (8), and a new sesquiterpene (11), together with 12 known compounds. Their structures were elucidated by the interpretation of extensive spectroscopic data, and the absolute configurations of 1-3 were established using calculations of ECD spectra, NMR data, and optical rotation values. Compound 1 possesses an unprecedented C25 liphatic polyketone skeleton. Compounds 5 and 10 exhibited potential cytotoxic activities against MCF-7 and HepG cells, and compounds 2, 7, and 9 exhibited potential neuroprotective activities in glutamate induced-PC12 injured cells.

Evaluation of microbial communities in peels of Brazilian tropical fruits by amplicon sequence analysis.

Elucidation of the distinctive microbial taxonomic profiles of tropical fruit peels is the indispensable component of investigations aimed at the detection of microorganisms responsible for the post-harvest loss. The objective of the present work was to dissect the bacterial and fungal community of five tropical fruit peels (banana, guava, mango, papaya, and passion fruit) in wild (non-cultivated) and conventionally produced samples from Brazil. To that end, 16S rRNA-encoding gene and ITS rDNA amplicon analysis of the five tropical fruit peels were performed to discriminate the bacterial and fungal communities, respectively. The result showed that bacterial communities of the five types of fruit peels were by far more diversified than that of fungal communities, independent of the type of production system involved. Among the investigated fruits, non-cultivated papaya peels hosted the most diversified bacterial community while the least bacterial community diversity was found in the conventionally produced papaya fruit peels. The gene amplicon analysis clearly discriminated the bacterial community into their respective classes, while fungal communities were better classified in their phyla, yet with clearer component discrimination of fungal community based on the type of cultivation system practiced. Conventionally produced banana and non-cultivated passion fruit peels were characteristically dominated by fungal and bacterial groups, respectively. Overall, in conventionally produced fruit peels, bacterial community was mainly composed of Proteobacteria, Actinobacteria, and Bacilli. The result provided a broad microbial diversity profile that could be used as an important input for seeking alternative fruit spoilage control and post-harvest treatments.

Avaliação antimicrobiana in vitro da nanoestrutura de óxido de zinco para posterior aplicação em embalagens / Antimicrobial evaluation in vitro of zinc oxide nanoestruture for subsequent application in packaging

A goiaba é uma das fruticulturas que se destaca no Brasil, por ser rica em nutrientes e ter elevada produção, porém há uma elevada perda/desperdício desse fruto pela sua alta perecibilidade. Logo, o objetivo deste estudo foi avaliar a atividade antimicrobiana das nanoestruturas de ZnO, a fim de aplicá-las em filmes de goma tara para preservação da goiaba. Foi feita a análise da curva de crescimento das bactérias Escherichia coli, Enterobacter cloacae, Salmonella typhimurium e Staphylococcus aureus na presença da nanoestrutura no leitor de microplaca. Estas apresentaram atividade antimicrobiana frente às bactérias, visto que houve o retardo do crescimento com o passar do tempo de análise. Verifica-se o potencial uso desta nanoestrutura para aumentar vida útil da goiaba.

Qualidade microbiológica de goiabas minimamente processadas comercializadas em João Pessoa, Paraíba / Microbiological quality of minimally processed guavas commercialized in João Pessoa, Paraíba

O consumo das frutas minimamente processadas vem crescendo cada dia mais devido a praticidade que estes produtos trazem para a vida das pessoas. O objetivo deste trabalho foi analisar a qualidade microbiológica de goiabas minimamente processadas comercializadas em hipermercados da cidade de João Pessoa, Paraíba. A pesquisa foi realizada com doze amostras de goiabas minimamente processadas. As análises microbiológicas foram realizadas para coliformes termotolerantes (45° C) e Salmonella spp. sendo os resultados comparados com os padrões legais. Verificou-se que a totalidade das amostras apresentaram valores <3 NMP/g para coliformes a 45º C, e em 25% houve presença de Salmonella spp. Este índice gera preocupação em relação à deficiência de práticas higiênico-sanitárias adequadas no processamento dos produtos.

First record of in vitro formation of ectomycorrhizae in Psidium cattleianum Sabine, a native Myrtaceae of the Brazilian Atlantic Forest.

Like many other species of trees native to the Brazilian Mata Atlântica (Atlantic Forest), the Myrtaceae, such as the Red Araza (Psidium cattleianum Sabine), are widely cited as arbuscular mycorrhizal formers. Nevertheless, recent studies show evidence that Myrtaceae from different tropical, subtropical and neotropical ecosystems can also prompt the formation of ectomycorrhizae, indicating that this species' ectomycorrhizal status should be further explored. Because of this, this research effort studied the in vitro interaction between the Red Araza and two ectomycorrhizal fungi isolates, belonging to the Pisolithus microcarpus (D17) and Scleroderma citrinum (UFSC-Sc133) species. An analysis was performed to determine the formation of ectomycorrhizal structures, or lack thereof, and the developmental differences between the in vitro mycorrhized and non-mycorrhized plants. The analysis proved that indeed an ectomycorrhizal association was developed between the Red Araza, and the D17 and UFSC-Sc133 isolates, a fact never before registered in the existing literature. After an in vitro period of 110 days, it was confirmed that the D17 and UFSC-Sc133 isolates formed mycorrhizal colonization of 91.6% and 15.7%, respectively. Furthermore, both isolates also promoted root thickening, and the formation of a fungal mantle and a Hartig net. However, when compared to the Control plants, the fungal isolates did not contribute to an increase in the development of the subject plants, possibly due to the specific experimental conditions used, such as a high humidity environment and high availability of nutrients in the symbiotic substrate.

Diversity of Neopestalotiopsis and Pestalotiopsis spp., Causal Agents of Guava Scab in Colombia.

Common guava (Psidium guajava L.) is a fruit tree of global economic importance. It is grown in Asia, South and Central America, and Hawaii for its exquisite aroma and flavor, and nutritional and medical properties. However, guava production is limited by guava scab, caused by fungi in the Pestalotiopsis genus. Characteristic symptoms of guava scab are corky, ovoid or round lesions on fruit surfaces. These lesions may thicken, affecting the flesh below and reducing fruit quality and commercial value. We characterized 81 isolates isolated from guava scab lesions on guava leaves and fruit in different regions of Colombia, and identified them as Pestalotiopsis and Neopestalotiopsis spp. We analyzed the morphology, pathogenicity, and genetic diversity of the isolates based on the sequences of the internal transcribed spacer, ß-tubulin, and elongation factor genes. Isolates were morphologically, pathogenically, and genetically diverse but the diversity did not correlate with geographical origin, or guava cultivar or tissue from which the isolates were recovered. Selected monosporic isolates included in the multiple-gene analysis were identified as belonging to two genera: Neopestalotiopsis (65 isolates with versicolorous conidia) and Pestalotiopsis (4 isolates with concolorous conidia).

Control of anthracnose caused by Colletotrichum species in guava, mango and papaya using synergistic combinations of chitosan and Cymbopogon citratus (D.C. ex Nees) Stapf. essential oil.

This study assessed the efficacy of chitosan (Chi) and Cymbopogon citratus (D.C. ex Nees) Stapf. essential oil (CCEO) combinations to control the mycelial growth of five pathogenic Colletotrichum species (C. asianum, C. siamense, C. fructicola, C. tropicale and C. karstii) in vitro, as well as the anthracnose development in guava (Psidium guajava L.) cv. Paluma, mango (Mangifera indica L.) cv. Tommy Atkins and papaya (Carica papaya L.) cv. Papaya artificially inoculated with these species. Combinations of Chi (2.5, 5 or 7.5mg/mL) and CCEO (0.15, 0.3, 0.6 or 1.25µL/mL) inhibited the mycelial growth of all tested fungal species in vitro. Examined Chi-CCEO combinations showed additive or synergistic interactions to inhibit the target Colletotrichum species based on the Abbott index. Coatings formed by synergistic Chi (5mg/mL) and CCEO (0.15, 0.3 or 0.6µL/mL) combinations decreased anthracnose lesion development in guava, mango and papaya inoculated with any of the tested Colleotrichum species during storage. Overall, anthracnose lesion development inhibition in fruit coated with synergistic Chi-CCEO combinations was higher than that observed in fruit treated with synthetic fungicides. These results show that the application of coatings formed by Chi-CCEO synergistic combinations could be effective to control postharvest anthracnose development in fruit.

The efficacy of Mentha arvensis L. and M. piperita L. essential oils in reducing pathogenic bacteria and maintaining quality characteristics in cashew, guava, mango, and pineapple juices.

This study evaluated the ability of the essential oil from Mentha arvensis L. (MAEO) and M. piperita L. (MPEO) to induce ≥5-log reductions in counts (CFU/mL) of E. coli, L. monocytogenes, and Salmonella enterica serovar Enteritidis in Brain-Heart Infusion broth (BHIB) and cashew, guava, mango, and pineapple juices during refrigerated storage (4±0.5°C). The effects of the incorporation of these essential oils on some physicochemical and sensory parameters of juices were also evaluated. The incorporation of 5, 2.5, 1.25, or 0.625µL/mL of MAEO in BHIB caused a ≥5-log reduction in counts of E. coli and Salmonella Enteritidis after 24h of storage; but only 5µL/mL was able to cause the same reduction in counts of L.monocytogenes. The incorporation of 10µL/mL of MPEO in BHIB caused a ≥5-log reduction in counts of E. coli, Salmonella Enteritidis, and L. monocytogenes after 24h of storage; smaller reductions were observed in BHIB containing 5, 2.5, and 1.25µL/mL of MPEO. Similar reductions were observed when the MAEO or MPEO was incorporated at the same concentrations in mango juice. The incorporation of MAEO or MPEO at all tested concentrations in cashew, guava, and pineapple juices resulted in a ≥5-log reduction in pathogen counts within 1h. The incorporation of MAEO and MPEO (0.625 and 1.25µL/mL, respectively) in fruit juices did not induce alterations in °Brix, pH, and acidity, but negatively affected the taste, aftertaste, and overall acceptance. The use of MAEO or MPEO at low concentrations could constitute an interesting tool to achieve the required 5-log reduction of pathogenic bacteria in cashew, guava, mango, and pineapple fruit juices. However, new methods combining the use of MAEO or MPEO with other technologies are necessary to reduce their negative impacts on specific sensory properties of these juices.

Species of the Colletotrichum acutatum complex associated with anthracnose diseases of fruit in Brazil.

Although Colletotrichum acutatum was recently investigated and shown to be a species complex comprising about 30 species, the name is still used in its broad sense for anthracnose pathogens of fruits in Brazil. In this study, a multilocus molecular analysis was carried out based on a dataset of ITS, HIS3, GAPDH, CHS-1, TUB2 and ACT sequences of Colletotrichum strains belonging to the C. acutatum species complex from fruits collected in different regions in Brazil combined with sequences of ex-type and other reference strains of species belonging to this complex. The strains were revealed to belong to Colletotrichum nymphaeae, Colletotrichum melonis, Colletotrichum abscissum and one new species, namely Colletotrichum paranaense, from apple and peach. Morphological descriptions of the new species and a strain closely related to but diverging from C. melonis are provided. From the data presently available, the most common species on apple fruits in Brazil is C. nymphaeae. In a pathogenicity test, strains of all four species caused lesions on detached apple, peach and guava fruits, except for strain CBS 134730 that did not infect guava fruits.

Label-Free Quantitative Proteomic Analysis of Puccinia psidii Uredospores Reveals Differences of Fungal Populations Infecting Eucalyptus and Guava.

Puccinia psidii sensu lato (s.l.) is the causal agent of eucalyptus and guava rust, but it also attacks a wide range of plant species from the myrtle family, resulting in a significant genetic and physiological variability among populations accessed from different hosts. The uredospores are crucial to P. psidii dissemination in the field. Although they are important for the fungal pathogenesis, their molecular characterization has been poorly studied. In this work, we report the first in-depth proteomic analysis of P. psidii s.l. uredospores from two contrasting populations: guava fruits (PpGuava) and eucalyptus leaves (PpEucalyptus). NanoUPLC-MSE was used to generate peptide spectra that were matched to the UniProt Puccinia genera sequences (UniProt database) resulting in the first proteomic analysis of the phytopathogenic fungus P. psidii. Three hundred and fourty proteins were detected and quantified using Label free proteomics. A significant number of unique proteins were found for each sample, others were significantly more or less abundant, according to the fungal populations. In PpGuava population, many proteins correlated with fungal virulence, such as malate dehydrogenase, proteossomes subunits, enolases and others were increased. On the other hand, PpEucalyptus proteins involved in biogenesis, protein folding and translocation were increased, supporting the physiological variability of the fungal populations according to their protein reservoirs and specific host interaction strategies.

Characterization of in vitro antifungal activities of small and American cranberry (Vaccinium oxycoccos L. and V. macrocarpon Aiton) and lingonberry (Vaccinium vitis-idaea L.) concentrates in sugar reduced fruit spreads.

In this study, cranberry and lingonberry concentrates were added to commercial sugar-reduced fruit spreads (raspberry-Aloe vera, strawberry-guava, and strawberry-lime), and tested for their antifungal activities. Selected strains of the species Absidia glauca, Penicillium brevicompactum, Saccharomyces cerevisiae and Zygosaccharomyces bailii, as well as xerophilic environmental isolates of the genera Penicillium and Eurotium were used for challenge testing. Initially, varying concentrations of synthetic antifungal agents, such as sodium benzoate, potassium sorbate and butyl 4-hydroxybenzoate were tested against these fungi on wort agar containing 31% fructose at different pH values. Subsequently, the experiments were conducted in fruit spreads containing different concentrations of cranberry and lingonberry concentrates. The results of this study demonstrate that these concentrates were able to inhibit growth of visible colonies of xerophilic and non-xerophilic fungi. Cranberry and lingonberry concentrates are interesting candidates for natural preservation against fungal growth in sugar reduced fruit spreads.

Dereplication-guided isolation of depsides thielavins S-T and lecanorins D-F from the endophytic fungus Setophoma sp.

Dereplication methodology using UHPLC-DAD-QTOFMS was applied during the metabolic profiling investigation of the endophyte Setophoma sp., a fungus isolated from symptomless guava fruits. The approach performed allowed a fast analysis of the microbial secondary metabolites. From this fungus, seven highly C-alkylated depsides were isolated and identified as polyketides thielavins S, T, U and V and lecanorins D, E and F. Their structures were elucidated through spectroscopic methods including NMR, HRMS and especially with assistance of HRMS/MS experiments. The compounds were tested for quorum sensing regulation activity in the virulence gene expression of Staphylococcus aureus, but no inhibitory effect was detected. Nevertheless, moderate antibacterial activity was encountered in three of tested depsides, particularly with thielavin T, whose MIC was 6.25 µg/mL against S. aureus.

Rust disease of eucalypts, caused by Puccinia psidii, did not originate via host jump from guava in Brazil.

The rust fungus, Puccinia psidii, is a devastating pathogen of introduced eucalypts (Eucalyptus spp.) in Brazil where it was first observed in 1912. This pathogen is hypothesized to be endemic to South and Central America and to have first infected eucalypts via a host jump from native guava (Psidium guajava). Ten microsatellite markers were used to genotype 148 P. psidii samples from eucalypts and guava plus five additional myrtaceous hosts across a wide geographic range of south-eastern Brazil and Uruguay. Principal coordinates analysis, a Bayesian clustering analysis and a minimum-spanning network revealed two major genetic clusters among the sampled isolates, one associated with guava and another associated with eucalypts and three additional hosts. Multilocus genotypes infecting guava differed by multiple mutational steps at eight loci compared with those infecting eucalypts. Approximate Bayesian computation revealed that evolutionary scenarios involving a coalescence event between guava- and eucalypt-associated pathogen populations within the past 1000 years are highly unlikely. None of the analyses supported the hypothesis that eucalypt-infecting P. psidii in Brazil originated via host jump from guava following the introduction of eucalypts to Brazil approximately 185 years ago. The existence of host-associated biotypes of P. psidii in Brazil indicates that this diversity must be considered when assessing the invasive threat posed by this pathogen to myrtaceous hosts worldwide.

PCR-RAPD profiling of Fusarium spp. causing guava wilt disease in India.

Wilt is a serious disease of the guava crop in India. Fusarium oxysporum f. sp. psidii and F. solani have been reported as causative agents of this disease. In this study, 42 isolates each of F. oxysporum f. sp. psidii and F. solani, were isolated from guava cultivars and characterized by randomly amplified polymorphic DNA (RAPD) method. Thirty RAPD primers were tested in the genome of Fusarium spp. and the number of scorable bands for corresponding primer ranged from 1-8 with an average of 5 bands per individual. DNA band size ranged from 200 bp to 5090 bp. A 0.21 per cent polymorphism was found in individual isolates of F. solani indicating that the 42 isolates were similar. However, a 2.58 percent polymorphism among individual isolates of F. oxysporum f.sp. psidii showed a higher level of genetic diversity. Cluster analysis of the RAPD band patterns clearly separated the isolates of F. oxysporum f.sp. psidii into three clusters. Two clusters were formed with F. solani isolates, showing a higher degree of similarity. Unique fingerprint profiles generated by the PCR-RAPD can be exploited for genetic characterization purposes.

Determinación del limite microbiano de jarabes de guayaba (Psidium SPP) comercializados en la ciudad de León julio - agosto de 2011 / Determination of the microbial limit of guava syrups (Psidium SPP) marketed in the city of León July - August 2011

El presente estudio de investigación trata de determinar el límite microbiano de jarabes de guayaba (Psidium spp.) comercializados en la ciudad de León (Nicaragua) cuantificando la cantidad total de microorganismos aerobios viables en la muestra e identificando la presencia de Escherichia coli, Salmonella spp, Pseudomona aeruginosa, Staphylococcus aureus, Clostridium spp, Shigella spp.