Helping Legumes under Stress Situations: Inoculation with Beneficial Microorganisms

In the upcoming years, legume crops will be subjected to multiple, diverse, and overlapping environmental stressors (raise in global temperatures and CO2, drought, salinity, and soil pollution). These factors will menace legume productivity and food quality and security. In this context, tolerant plant growth promoting rhizobacteria (PGPR) are useful biotechnological tools to assist legume establishment and growth. In this chapter, tolerant PGPR able to promote legume growth will be revised. Besides, in the era of -omics, the mechanisms underlying this interaction are being deciphered, particularly transcriptomic, proteomic, and metabolomic changes modulated by PGPR, as well as the molecular dialog legume-rhizobacteria

Species disparity response to mutagenesis of marine yeasts for the potential production of biodiesel

Background: Among the third-generation biodiesel feed stock, oleaginous marine yeasts are the least studied microorganisms for such purpose. Results: Wild strains yeasts were isolated from various Tunisian marine sources including fish waste (Candida tenuis CtTun15, Debaryomyces hansenii DhTun2015, Trichosporon asahii TaTun15 and Yarrowia lipolytica YlTun15) and seawater (Rhodotorula mucilaginosa RmTun15). Following incubation with ethyl methanesulfonate (EMS: 75 mM) for various periods of time (T15, T30, T45, T60 min), the cell viability of these strains responded differentially according to yeast species. For instance, mutated CtTun15 did not survive after 30 min of EMS treatment; higher resistances were observed in DhTun2015 (45 min), in YlTun15, RmTun15 and in TaTun15 (60 min) but with significant decreased cell viabilities (survival rate: 6.02, 3.16, 11.22, 11.58, 7.70%, respectively). For all surviving mutated strains, the optima of biomass and lipid yields were detected after 96 h in YPD culture; but derived from strains submitted to different period of EMS incubation. In most mutated strains, the maximum biomass (BP) and lipid (LP) productivities coincided and were observed after 30 min of EMS incubation. Only CtTun15 showed different optima of BP and LP (after 30 min and 15 min, respectively). The fatty acids (FA) compositions considered essential in the prediction of biodiesel criteria; were highly affected by EMS mutagenesis. Essentially, 30- and 45-min EMS incubation induced the highest levels of PUFA and MUFA in YlTun15, RmTun15 and TaTun15 with non-significant differences in the different times. However, CtTun15 and DhTun2015 mutant strains responded differently, with the highest levels of MUFA observed following 15 and 45 min; and that of PUFA after 30 and 45 min, respectively. Conclusion: The methyl-esterification of FA from the three mutated yeast strains (30 min - YlTun15, RmTun15 and TaTun15) yielded biodiesel with physical proprieties consistent with the International Standard System. However, investigations are needed for up-scaling biodiesel production

EM algorithm and Varible Neighborhood Search for fitting Finite Mixture Model parameters

Finding maximum likelihood parameter values for Finite Mixture Model (FMM) is often done with the Expectation Maximization (EM) algorithm. However the choice of initial values can severely affect the time to attain convergence of the algorithm and its efficiency in finding global maxima. We alleviate this defect by embedding the EM algorithm within the variable Neighborhood Search (VNS) methaheurestic framework. Computational experiment in several problems in literature as well as some larger ones are reported

Etat des ressources génétiques de la population locale du poulet de Tunisie

Genetic Resources of the Local Chickens in Tunisia. The opportunity to develop rural livestock and poultry genetic resources in Tunisia has been discussed by giving historical rural poultry origins and structures through trials and sample surveys on their performances and polymorphism. The poultry phenotypes observed in the north-east rural area of Tunisia (i.e. Ariana and Bizerte) are various and their performances were low and vary a lot. Local rural hen can produce an average of 127 eggs per year and its weight reaches 1.206 kg at age 18 weeks. While the cocks have a body weight of 1.620 kg at the same age. Despite the genetic erosion which they have endured over the centuries, the local chicken populations in Tunisia succeeded in preserving a sufficiently significant variability; this allows them to guaranty not only a minimum egg production level and a first choice quality meet, but also to preserve a unique gene reserves of various types and characteristics (i.e. colour, form, rusticity, etc.). The wealth of the genetic resources of the poultry rural population in Tunisia, well identified in this work, makes us believe that a gene conservation program is highly recommended to promote Tunisian rural poultry

Alfa fibres for unsaturated polyester composites reinforcement: Effects of chemical treatments on mechanical and permeation properties

International audienc

Kinetics of water sorption in flax and PET fibers

International audienceComposite materials are usually reinforced by synthetic fibers as carbon, glass etc.... Because of their good mechanical properties and low density, natural fibers are being considered more preferentially as reinforcement. The application of natural fibers as reinforcements in composite materials requires a strong adhesion between the fiber and the matrix. The poor resistance towards water absorption is one of the drawbacks of natural fibers which makes it more important to understand the dynamic properties of penetration of water molecules through these heterogeneous materials. Water vapour sorption kinetics in natural flax fibers have been performed at 25 °C by using an electronic microbalance (IGA, Hiden). By using the Fickian model for a complete cylinder water diffusion coefficients have been determined and calculated at short times (first half-sorption) and long times (second half-sorption) of kinetic curve and for different water activities. The values obtained for D1 and D2 are rather similar on the all range of water activity. Generally, water diffusivity increases and then decreases with water activity. The increase of diffusivity at low water activities may be explained on the basis of the dual mode sorption (Langmuir and Henry sorption's combination) whereas the decrease for the higher activities can be attributed to the immobilization of sorbed water molecules due to the water clustering

Molecular Identification and Biochemical Characterization of Novel Marine Yeast Strains with Potential Application in Industrial Biotechnology

Cell-based agriculture is an emerging and attractive alternative to produce various food ingredients. In this study, five strains of marine yeast were isolated, molecularly identified and biochemically characterized. Molecular identification was realized by sequencing the DNA ITS1 and D1/D2 region, and sequences were registered in GenBank as Yarrowia lipolytica YlTun15, Rhodotorula mucilaginosa RmTun15, Candida tenuis CtTun15, Debaryomyces hansenii DhTun2015 and Trichosporon asahii TaTun15. Yeasts showed protein content varying from 26% (YlTun15) to 40% (CtTun15 and DhTun2015), and essential amino acids ranging from 38.1 to 64.4% of the total AAs (CtTun15-YlTun15, respectively). Lipid content varied from 11.15 to 37.57% with substantial amount of PUFA (>12% in RmTun15). All species had low levels of Na (<0.15 mg/100 g) but are a good source of Ca and K. Yeast cytotoxic effect was investigated against human embryonic kidney cells (HEK 293); results showed improved cell viability with all added strains, indicating safety of the strains used. Based on thorough literature investigation and yeast composition, the five identified strains could be classified not only as oleaginous yeasts but also as single cell protein (SCP) (DhTun2015 and CtTun15) and single cell oil (SCO) (RmTun15, YlTun15 and TaTun15) producers; and therefore, they represent a source of alternative ingredients for food, feed and other sectors