In-vitro assessment for the control of Fusarium species using a lactic acid bacterium isolated from yellow pitahaya(Selenicereus megalanthus(K. Schum. Ex Vaupel Moran))

The fungistatic activity of a lactic acid bacterium, which had been isolated from yellow pitahaya cultures, against fungi associated with basal rot(Fusarium oxysporum and Fusarium fujikuroi) was measured in the present study. Its activity was assessed in three fractions: fermented(S1), metabolic products(S2), and biomass(S3), using two fermentation substrates: Man Rogosa Sharpe agar(MRS) and potato dextrose agar(PDA). The bacterium was molecularly identified as Lactobacillus plantarum. S3 reduced F. fujikuroi growth by 100% over 48 h of fermentation, which occurred during the stationary phase of bacterial growth. The three fractions' fungistatic activity against F. fujikuroi depended on the substrate employed. The fermentation kinetic parameters for L. plantarum indicated that its specific growth rate was 0.46 h^–1, with 93.63% substrate consumption, 0.045 kg kg^–1 cell yield, and 0.54 kg kg^–1 product yield. The kinetic parameters calculated will allow for bacteria production scaling. These in-vitro trials reveal L. plantarum's possible application as a biocontrol agent for diseases associated with Fusarium. However, further ex-vivo and in-vivo researches are required to demonstrate its behavior in crops.

Polyurethane as substrate for fungal strains

Polyurethane is a versatile plastic with several industrial applications in the modern life, but it is considered as a very recalcitrant material. Biodegradation of this plastic has been poorly explored, and most of the studies that have been published focus on bacterial enzymes. In this work, some fungi with the capacity of growing with polyurethane foam as nutrient source were isolated from sands contaminated with this plastic and from DIA/UAdeC collection, testing their ability to grow on polyurethane as sole carbon and nitrogen sources and their enzymatic activities were determined in specific media as well as their invasion capacity on polyurethane agar plates. 22 fungal strains demonstrated their capacity of growing on polyurethane. Among the enzymatic activities evaluate, the most common was the urease activity (95% of the strains).Protease, esterase and laccase activities were present in 86%, 50% and 36% respectively. The great ability of the isolated fungal strains to use polyurethane foam as nutrient opens an important opportunity to study at detail the biodegradation of this plastic, with clear implications in cell biology and environmental technology.

Development and characterization of whey protein films incorporated with tarbush polyphenols and candelilla wax

Edible films were prepared with whey protein incorporating candelilla wax,and glycerol in aqueous solution.Tarbush polyphenols were added as bioactive agent.An optimization based on the water vapor permeability(WVP)of the formulation was performed using a Box-Behnken design.The films were characterized by the determination of WVP,moisture,solubility,color,antioxidant and antifungal activity.Scanning electron microscopy(SEM)was also performed to observe the surface and cross-section micrographs.The lowest permeability values were found with concentrations of 1.27,0.3 and 0.5% of protein,wax and glycerol respectively.It was proved that the addition of polyphenols into films causes a significant effect only on solubility and transparency characteristics.Edible films have suitable properties as a barrier for the goods they could be applied on.It is proposed for use in foods such as fresh or minimally processed fruits and vegetables.