Whole-genome analysis suggesting probiotic potential and safety properties of Pediococcus pentosaceus DSPZPP1, a promising LAB strain isolated from traditional fermented sausages of the Basilicata region (Southern Italy)

Introduction

Many lactic acid bacteria (LAB) strains are currently gaining attention in the food industry and various biological applications because of their harmless and functional properties. Given the growing consumer demand for safe food, further research into potential probiotic bacteria is beneficial. Therefore, we aimed to characterize Pediococcus pentosaceus DSPZPP1, a LAB strain isolated from traditional fermented sausages from the Basilicata region of Southern Italy.

Methods

In this study, we analyzed the whole genome of the P. pentosaceus DSPZPP1 strain and performed in silico characterization to evaluate its applicability for probiotics and use in the food industry.

Results and Discussion

The whole-genome assembly and functional annotations revealed many interesting characteristics of the DSPZPP1 strain. Sequencing raw reads were assembled into a draft genome of size 1,891,398 bp, with a G + C content of 37.3%. Functional annotation identified 1930 protein-encoding genes and 58 RNAs including tRNA, tmRNA, and 16S, 23S, and 5S rRNAs. The analysis shows the presence of genes that encode water-soluble B-group vitamins such as biotin, folate, coenzyme A, and riboflavin. Furthermore, the analysis revealed that the DSPZPP1 strain can synthesize class II bacteriocin, penocin A, adding importance to the food industry for bio-enriched food. The DSPZPP1 genome does not show the presence of plasmids, and no genes associated with antimicrobial resistance and virulence were found. In addition, two intact bacteriophages were identified. Importantly, the lowest probability value in pathogenicity analysis indicates that this strain is non-pathogenic to humans. 16 s rRNA-based phylogenetic analysis and comparative analysis based on ANI and Tetra reveal that the DSPZPP1 strain shares the closest evolutionary relationship with P. pentosaceus DSM 20336 and other Pediococcus strains. Analysis of carbohydrate active enzymes (CAZymes) identified glycosyl transferases (GT) as a main class of enzymes followed by glycoside hydrolases (GH). Our study shows several interesting characteristics of the isolated DSPZPP1 strain from fermented Italian sausages, suggesting its potential use as a promising probiotic candidate and making it more appropriate for selection as a future additive in biopreservation.

Alternative Ecological Products for Aphid Control on Plum

Ecological farming is increasing worldwide, as more and more consumers prefer chemical-free fruits. As a result, ecological farming is becoming increasingly appealing to European farmers, including those in Romania. However, implementing an effective ecological phytosanitary program remains a challenge for farmers due to limited options and a lack of information about their effectiveness. Romania is a major producer of plums and ranks second in the world after China. Aphids are common pests of plum, and some species are vectors of the damaging Plum pox virus, and therefore require special attention regarding their control. Eight ecological products were tested both in the field and laboratory for a duration of three vegetative periods to determine their efficiency in aphid control. The effects of ecological products were compared with five chemical insecticides known to be effective against aphids. Observations were made 24 and 48 h after spraying. Two of the eight ecological products tested were proven to be efficient in aphid control, Ovipron Top and Prev-Am, with a mortality rate over 90%. The results indicate that these two ecological products are comparable in effectiveness to chemical insecticides and could be suitable candidates for both ecological and conventional treatment programs.

Antimicrobial and antioxidant properties and quantitative screening of phytochemicals of Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures

The antioxidant and antimicrobial activities of Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures against a range of foodborne bacteria were investigated to determine the major components and to analyse the action spectrum and antimicrobial effectiveness of the extracts. Results demonstrated a significant antioxidant activity of Fraxinus excelsior L. and a lower activity of Eschscholtzia californica Cham. and a good chemical phenolic composition with the highest content of flavonoids. The Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures demonstrated a middle-high antimicrobial activity against, respectively, 66.67% and 43.33% of all tested bacteria. The inhibitory activity showed a moderate effect on the growth of the sensitive strains in presence of extracts minimum inhibitory concentration. The synergistic actions of bioactive compounds detected in the extracts might be on the basis of antioxidant and biological activities observed and should be used in pharmaceutical, food preservation, alternative medicine and natural therapies fields.

Effects of Trichoderma harzianum Strain T22 on the Arthropod Community Associated with Tomato Plants and on the Crop Performance in an Experimental Field

Fungi belonging to the genus Trichoderma have received much attention in recent years due to their beneficial effects on crop health and their use as pest control agents. Trichoderma activates direct plant defenses against phytophagous arthropods and reinforces indirect plant defense through the attraction of predators. Although the plant defenses against insect herbivores were demonstrated in laboratory experiments, little attention has been paid to the use of Trichoderma spp. in open field conditions. In the present study, we investigated the effects of the inoculation of the commercial Trichoderma harzianum strain T22 on the arthropod community associated with tomato plants and on the crop performance in an experimental field located in South Italy. Our results showed that inoculation with T. harzianum could alter the arthropod community and reduce the abundance of specific pests under field conditions with respect to the sampling period. The present study also confirmed the beneficial effect of T. harzianum against plant pathogens and on tomato fruit. The complex tomato-arthropod-microorganism interactions that occurred in the field are discussed to enrich our current information on the possibilities of using Trichoderma as a green alternative agent in agriculture.

Alternative Control of Phragmidium rubi-idaei Infecting Two Rubus Species

Organic berry plantations have been gaining popularity among farmers during recent years. Even so, farmers experience serious challenges in disease control management, which is a concern in organic farming. Phragmidium rubi-idaei (DC) P. Karst is the pathogen responsible for blackberry and raspberry rust disease, one of the most present and active diseases in plantations. The antifungal certified products found on the organic farming market offer the opportunity for an efficient control strategy over plant pathogens in fruit shrub plantations. In this study, 5 natural based products—namely Altosan, Mimox, Canelys, Zitron, and Zeolite—were tested for their fungistatic effect over P. rubi-idaei. The experiments were carried out under laboratory conditions, performing observations over the impact of organic products, used at different concentration levels, on rust conidia germination. Moreover, field experiments were conducted in order to evaluate the efficiency of different treatments for rust control on raspberry (‘Polka’, ‘Veten’ and ‘Heritage’) and blackberry (‘Thorn Free’, ‘Chester’ and ‘Loch Ness’) varieties. Data analysis based on ANOVA tests showed significant differences between the tested variants and the control sample at p < 0.001. Furthermore, LSD test confirmed differences between all substances tested (p < 0.005). The natural products Canelys (formulated with cinnamon) and Zytron (based on citrus extract) have proven the highest inhibitory capacity for conidia germination during in vitro tests registering values of 80.42% and 78.34%, respectively. The same high inhibitory rates against rust pathogen were kept also in the field tests using the same two natural-based products mentioned earlier. In addition, outcomes from this study demonstrated that Zeolite is not recommended for raspberry or blackberry rust control.

An In Vitro Attempt for Controlling Severe Phytopathogens and Human Pathogens Using Essential Oils from Mediterranean Plants of Genus Schinus

Growing concerns about food safety and environmental protection enhanced the need for new and safe plant disease control strategies. The chemical composition of the three essential oils (EOs) extracted from leaves and fruits of Schinus terebinthifolius and leaves of Schinus molle, growing in Tunisia, was studied by GC and GC-MS. In all, 12 compounds were identified. The oils were mainly composed of terpene compounds. α-Pinene, α-phellandrene, and D-limonene were the major constituents. The aim of the current study was to evaluate the in vitro antimicrobial effectiveness of three EOs derived from plants of genus Schinus and extracted from leaves and fruits of S. terebinthifolius and leaves of S. molle. Both antifungal and antibacterial activities of the EOs were examined. The antifungal activity of the studied EOs was investigated against Colletotrichum acutatum and Botrytis cinerea in comparison with the systemic fungicide azoxystrobin used at 0.8 μL mL(-1). The antibacterial activity was evaluated against three strains of Gram-positive (G+ve) bacteria (Bacillus megaterium, Bacillus mojavensis and Clavibacter michiganensis) and four strains of Gram-negative (G-ve) bacteria (Escherichia coli, Xanthomonas campestris, Pseudomonas savastanoi, and Pseudomonas syringae pv. phaseolicola) compared with the synthetic antibiotic tetracycline at a concentration of 1600 μg mL(-1). The minimum inhibitory concentration of the studied EOs has been evaluated against the above microorganisms using the 96-well microplate method. Tested microorganisms exhibited different levels of sensitivity to each tested EO. All investigated EOs reduced the fungal mycelial growth when used at low concentrations from 250 to 1000 ppm and from 2000 to 8000 ppm against C. acutatum and B. cinerea, respectively. Higher concentrations of the same EOs exhibited a fungicidal effect against both mitosporic fungi. The EO extracted from leaves of S. terebinthifolius significantly inhibited the growth of tested bacterial strains. Nevertheless, E. coli showed a weak resistance toward the same EO and a high resistance toward the other two tested EOs. Finally, P. savastanoi and P. syringae pv. phaseolicola showed a high resistance toward all tested EOs.

First Report of Albugo candida Causing White Rust on Lunaria annua in Italy

Money plant or annual honesty (Lunaria annua L.) is an ornamental landscape plant used in flower beds and borders and also in flower arrangements. It is a biennial plant with large, pointed, oval leaves. Plants of L. annua showing white-to-cream, blister-like lesions on leaves and siliques (2) were found in private gardens where approximately 800 plants of 1,000 (approximately 80 to 90%) that were observed showed symptoms. The disease was also found in two ornamental nurseries, although it was limited to a few mother plants because of extensive fungicide treatments. The gardens and ornamental nurseries were located in Potenza Province (Basilicata Region, southern Italy). Sporangiophores were mostly straight or arched and almost cylindrical with attenuated base and flat or rounded apex and measured 29.2 to 33.4 × 12.8 to 13.4 μm. Sporangia, produced in chains and joined by short connectives, exhibited a spherical or angular shape, were subhyaline, contained vacuoles, and had average maximum and minimum diameters ranging from 15.8 to 18.8 and 14 to 16 μm, respectively. The morphological characteristics closely resembled those reported for Albugo candida (Pers.) Kuntze (3). Sori were collected from naturally and artificially inoculated tissues of L. annua, with the aid of a stereomicroscope, and used to extract genomic DNA via a DNeasy Plant Mini DNA extraction kit (Qiagen, Hilden, Germany) according to the manufacturer's directions. The extracted DNA was used as a template for amplification of the internal transcribed spacer (ITS) region of rDNA with primer pair ITS4/DC6 (1,4) and sequenced. One sequence, GenBank Accession No. GQ328846, matched several sequences of A. candida (Pers). Kuntze (e.g., GenBank Accession Nos. GQ328837, GQ328836, GQ328835, GQ328834, and AF271231), showing 98% identity. Pathogenicity tests were performed and repeated twice. Leaves of 10 healthy seedlings of L. annua were surface cleaned during several washings with distilled water and then spray inoculated with a suspension of 10³ sporangia/ml of A. candida. Five healthy seedlings were spray inoculated with the same volume of sterile water and served as controls. Inoculated seedlings were maintained in a moist chamber for 48 h at 20°C before being moved to a shaded glasshouse at 16 to 24°C and 90% relative humidity. White rust symptoms, similar to those observed in natural conditions, appeared on leaves of inoculated seedlings 10 to 14 days later, demonstrating that A. candida was the causal agent of the disease. Control plants remained symptomless. White rust has been reported on L. annua in Europe (Czech Republic, Germany, Poland, and the United Kingdom) and in the northwestern United States (3). To our knowledge, this is the first report of A. candida infecting annual honesty plant in Italy. References: (1) P. Bonants et al. Eur. J. Plant Pathol. 103:345, 1997. (2) D. Choi et al. Mycotaxon 53:261, 1995. (3) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2004-0317-01-HN. Plant Health Progress, 2004. (4) T. J. White et al. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: PCR Protocols. A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.