The use of bioeffectors, formally known as plant biostimulants, has become common practice in agriculture and provides a number of benefits in stimulating growth and protecting against stress. A biostimulant is loosely defined as an organic material and/or microorganism that is applied to enhance nutrient uptake, stimulate growth, enhance stress tolerance or crop quality. This review is intended to provide a broad overview of known effects of biostimulants and their ability to improve tolerance to abiotic stresses. Inoculation or application of extracts from algae or other plants have beneficial effects on growth and stress adaptation. Algal extracts, protein hydrolysates, humic and fulvic acids, and other compounded mixtures have properties beyond basic nutrition, often enhancing growth and stress tolerance. Non-pathogenic bacteria capable of colonizing roots and the rhizosphere also have a number of positive effects. These effects include higher yield, enhanced nutrient uptake and utilization, increased photosynthetic activity, and resistance to both biotic and abiotic stresses. While most biostimulants have numerous and diverse effects on plant growth, this review focuses on the bioprotective effects against abiotic stress. Agricultural biostimulants may contribute to make agriculture more sustainable and resilient and offer an alternative to synthetic protectants which have increasingly falling out of favour with consumers. An extensive review of the literature shows a clear role for a diverse number of biostimulants that have protective effects against abiotic stress but also reveals the urgent need to address the underlying mechanisms responsible for these effects.

Microbial inoculants such as Trichoderma-based products are receiving great interest among researchers and agricultural producers for their potential to improve crop productivity, nutritional quality as well as resistance to plant pathogens/pests and numerous environmental stresses. Two greenhouse experiments were conducted to assess the effects of Trichoderma-based biostimulants under suboptimal, optimal and supraoptimal levels of nitrogen (N) fertilization in two leafy vegetables: Iceberg lettuce (Lactuca sativa L.) and rocket (Eruca sativa Mill.). The yield, nutritional characteristics, N uptake and mineral composition were analyzed for each vegetable crop after inoculation with Trichoderma strains T. virens (GV41) or T. harzianum (T22), and results were compared to non-inoculated plants. In addition, the effect of the Trichoderma-based biostimulants on microbes associated with the rhizosphere in terms of prokaryotic and eukaryotic composition and concentration using DGGE was also evaluated. Trichoderma-based biostimulants, in particular GV41, positively increased lettuce and rocket yield in the unfertilized plots. The highest marketable lettuce fresh yield was recorded with either of the biostimulant inoculations when plants were supplied with optimal levels of N. The inoculation of rocket with GV41, and to a lesser degree with T22, elicited an increase in total ascorbic acid under both optimal and high N conditions. T. virens GV41 increased N-use efficiency of lettuce, and favored the uptake of native N present in the soil of both lettuce and rocket. The positive effect of biostimulants on nutrient uptake and crop growth was species-dependent, being more marked with lettuce. The best biostimulation effects from the Trichoderma treatments were observed in both crops when grown under low N availability. The Trichoderma inoculation strongly influenced the composition of eukaryotic populations in the rhizosphere, in particularly exerting different effects with low N levels in comparison to the N fertilized plots. Overall, inoculations with Trichoderma may be considered as a viable strategy to manage the nutrient content of leafy horticulture crops cultivated in low fertility soils, and assist vegetable growers in reducing the use of synthetic fertilizers, developing sustainable management practices to optimize N use efficiency.

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Aims: Evaluation of the occurrence of most known staphylococcal enterotoxin (SE) genes, egc (enterotoxin gene cluster) and TSST1 (toxic shock syndrome toxin 1) gene in both coagulase-positive (CPS) and coagulase-negative (CNS) staphylococcal strains isolated from meat and dairy products. Methods and Results: Specificity and reliability of the PCR detection methods used were ascertained by using nine reference strains of Staphylococcus (S. aureus) harbouring SE genes (seA to seE; seG, seH, seI, seM, seJ, seN and seO) and egc (containing the following sequence of genes: seO, seM, seI, uent1, uent2, seN and seG). Of 109 wild Staphylococcus spp. strains analysed, only 11 S. aureus strains were SE and/or TSST1 PCR-positive. The last 11 strains also appeared to harbour the egc. Restriction endonuclease analysis of part of the egc of both reference and wild strains showed that different variants of the egc exist. Moreover, nucleotide sequences of seG and seI indicate that the egc of the strain AB-8802 is characterized by the presence of variants of these enterotoxins (seGv and seIv). Conclusions: The occurrence of SE genes in CNS and other non-S. aureus species isolated from Napoli-type salami, raw water buffalo milk and natural whey cultures used for mozzarella cheese manufacturing is very rare. Significance and Impact of the Study: During this study it was shown that at least five different egc may exist in S. aureus. A thorough study of egc polymorphism should provide further insight into the phylogenetics of the egc.

The aims of this study were to evaluate the microbial diversity of different lignocellulosic biomasses during degradation under natural conditions and to isolate, select, characterise new well-adapted bacterial strains to detect potentially improved enzyme-producing bacteria. The microbiota of biomass piles of Arundo donax, Eucalyptus camaldulensis and Populus nigra were evaluated by high-throughput sequencing. A highly complex bacterial community was found, composed of ubiquitous bacteria, with the highest representation by the Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes phyla. The abundances of the major and minor taxa retrieved during the process were determined by the selective pressure produced by the lignocellulosic plant species and degradation conditions. Moreover, cellulolytic bacteria were isolated using differential substrates and screened for cellulase, cellobiase, xylanase, pectinase and ligninase activities. Forty strains that showed multienzymatic activity were selected and identified. The highest endo-cellulase activity was seen in Promicromonospora sukumoe CE86 and Isoptericola variabilis CA84, which were able to degrade cellulose, cellobiose and xylan. Sixty-two percent of bacterial strains tested exhibited high extracellular endo-1,4-ß-glucanase activity in liquid media. These approaches show that the microbiota of lignocellulosic biomasses can be considered an important source of bacterial strains to upgrade the feasibility of lignocellulose conversion for the ‘greener' technology of second-generation biofuels.

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Species-specific primers and a multiplex PCR assay were developed for the simultaneous identification and differentiation of Pseudomonas fragi, P. lundensis, and P. putida based on the coamplification of different portions of the small subunit of the carbamoyl phosphate synthase gene (carA). The carA multiplex PCR was used to detect the presence of the three Pseudomonas species from beef, chicken, and pork samples and proved to be effective in showing their evolution during the storage of meat.Several species of the genus Pseudomonas are very often recognized as the principal causative agents of the spoilage of fresh foods stored aerobically. Members of the Pseudomonas fluorescens group, along with the psychrotrophic P. fragi, P. lundensis, and P. putida, are usually involved in spoilage of milk, meat, and fish, even during storage at low temperatures. These bacteria are often isolated from spoiled meat (10,12,18).The molecular detection and identification of microorganisms is widely used in food microbiology. However, only limited information is now available on the molecular detection of spoilage bacteria, and the development of appropriate strategies for their rapid identification and monitoring is needed. Some molecular approaches, such as ribotyping, PCR amplification of the 16S-23S rRNA gene spacer region, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, have been exploited for the analysis of the diversity of Pseudomonas isolates from foods (4,13,19,21).The molecular identification of Pseudomonas is often difficult and controversial. The sequence analysis of the 16S rRNA gene is widely employed for the identification of bacteria; however, this region is not satisfactorily discriminating between the species of Pseudomonas. Phylogenetic studies have highlighted that inferred phylogenies based on the 16S rRNA gene lack resolution at the intrageneric level because of its low rate of evolution (1,15,20). In recent studies on the spoilage-related microbiota of beef, we also realized that it was difficult to achieve an unequivocal identification of Pseudomonas at the species level, even though variable regions of the 16S rRNA gene were analyzed (7,17). Several authors have evaluated the use of alternative sequences for the identification and phylogenetic studies of Pseudomonas spp. For this purpose, the sequences of the carA, recA, gyrB, fliC, and rpoD genes of Pseudomonas species have been determined (2,11,20). The sequences of the carbamoyl phosphate synthase gene small subunit (carA) of several Pseudomonas spp. of environmental origin have been determined by Hilario et al. (11). However, the carA sequences for species of food interest, such as P. fragi and P. lundensis, were not considered.In this study, the carA gene sequence was used as a target in order to design species-specific primers to selectively and simultaneously detect P. fragi, P. lundensis, and P. putida from meat.carA gene sequencing and primer design. The Pseudomonas strains used in this study are listed in Table 1. They were cul...