Virulence variations between clonal complexes of Melisococcus plutonius and the possible causes.

Melissococcus plutonius is a pathogenic bacterium that affects honeybee brood triggering colony collapse in severe cases. The bacterium causes a European foulbrood (EFB) disease in the honeybee populations, impacting beekeeping and agricultural industries. The pathogenesis, epidemiology, and variants of M. plutonius have been studied, but the virulence factors involved in larval infection are still unknown. Recently, an in-silico study suggested putative genes that might play a role in the pathogenesis of EFB. However, studies are required to determine their function as virulence factors. In addition, the few studies of clonal complexes (CCs), virulence factors, and variation in the honeybee larvae mortality have interfered with the development of more efficient control methods. The research, development, and differences in virulence between genetic variants (CCs) of M. plutonius and potential virulence factors implicated in honeybee larval mortality are discussed in this review.

Effect of fiber fractions of prickly pear cactus (nopal) on quality and sensory properties of wheat bread rolls.

In this study the addition of total fiber (TF), insoluble fiber (IF), and soluble fiber (SF) from nopal to wheat flour used to make bread rolls was assessed. The rheological properties of dough as well as quality, texture, sensorial and physical characteristics of the crumb rolls produced were evaluated. The storage (23.50 MPa) and loss modulus (11.95 MPa) for SF-dough were the lowest indicating that a less visco-elastic behavior was obtained. Polarized light microscopy showed that a more homogeneous size and a better distribution of starch granules were developed into SF-dough. Crumb hardness (3.25-4.78 N) and chewiness (0.31-0.81 N) of SF-rolls were lower than the control experiment (3.99-5.81 N and 0.35-1.01 N respectively). Springiness for all treatments was constant (1.0) compared with the control (1.02-0.87) for 2 days of storage. The lowest cohesiveness values (0.24-014) were computed by IF treatment for a similar storage time. The specific crumb volume increased by 12.46, 9.03 and 1.10 % by the addition of SF, TF and IF respectively. The lowest rate of staling was shown by SF-rolls (0.199) and it was followed by TF (0.296), IF (0.381) and control (0.458) treatments. As a result, the highest scores on quality (9.3 out of 10) and sensorial attributes (from 8.9 up to 9.7) were assigned to SF-rolls.

Effect of the perforation level of recycled-LDPE bags on the modification of the atmosphere development, bioactive compounds content, and other qualities of Jalapeño peppers during storage.

The impact of modified atmosphere packaging on the content of selected bioactive compounds and other quality attributes of Jalapeño peppers has not been well studied. In this study, Jalapeño peppers were packed in low-cost bags (composed of recycled-LDPE) that had been perforated at several levels (0-4 holes). Packages were stored at 7 °C for 6 weeks. Samples of unpacked peppers were stored at 23 and 7 °C and were used as control groups. The quality of the peppers and the gas composition inside of the packages were evaluated during storage. The best modified atmosphere was obtained with unperforated bags. Significant loss of weight and firmness were prevented by packaging. The loss of weight and firmness were 20.2-82.6 and 32-100 % in unpacked peppers. Low levels of fermentative metabolites accumulated in packed peppers in unperforated bags and in bags with 1 perforation. The tristimulus color and the bioactive compounds content (phenols, ascorbic acid, ß-carotene, and capsaicinoids) remained unchanged in packed peppers. These quality attributes changed gradually in peppers that were stored at 23 °C. The tested bags represent a cost-effective alternative to preserve the quality of intact Jalapeño peppers.

Morphological, Biological, and Molecular Characterization of Type I Granuloviruses of Spodoptera frugiperda.

Granuloviruses (GVs) Betabaculovirus associated with the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), especially those of the type I, have scarcely been studied. These GVs might be an effective alternative for the biocontrol of this insect. In this study, the native GVs SfGV-CH13 and SfGV-CH28 were isolated from FAW larvae and characterized for morphology, molecular traits, and insecticidal activity. The elapsed time between symptomatic infection of larvae and stop feeding as well as the weight of larvae before death or prior to pupation were also evaluated. Both GVs had ovoid shape and a length of 0.4 µm. They had the same DNA restriction profiles and their genome sizes were about 126 kb. The symptomatic infection with the tested GVs mainly caused flaccidity of larva body and discoloration of integument. The integument lysis was only observed in 8% of infected larvae. Infected larvae gradually stopped feeding. Overall, these symptoms are characteristic of infections caused by type I GVs, which are known as monoorganotropic or slow-killing GVs. The median lethal dose (LD50) values for SfGV-CH13 and SfGV-CH28 isolates were 5.4 × 102 and 1.1 × 103 OBs/larva, respectively. The median lethal time (LT50) ranged from 17 to 24 days. LT50 values decreased as the viral dose was increased. The elapsed time from symptomatic infection until pupation and body weight of larvae (third instar) were higher with SfGV-CH28 than SfGV-CH13. Both granulovirus isolates were able to kill the FAW larvae from the 12th day.

Characterization of insect chitosan films from Tenebrio molitor and Brachystola magna and its comparison with commercial chitosan of different molecular weights.

Insects are considered as alternative sources of chitosan; however, studies about the functional film-forming properties of insect chitosan are scarce. Insect chitosan films were made from Tenebrio molitor and Brachystola magna and were compared with commercial chitosan of different molecular weights (Mw). Mechanical properties (tensile strength, TS; elastic modulus, EM; elongation at break, %E), water vapor permeability (WVP) and physicochemical properties were characterized. The film properties of both commercial and insect chitosan were affected by Mw. Commercial chitosan films showed that at lower Mw, the TS (from 59 to 48 MPa) and EM (from 1471 to 1286 MPa) decreased; whereas WVP (from 2.9 × 10-11 to 3.4 × 10-11 g m-1s-1Pa-1), % E (from 38 to 41%) and solubility (from 30 to 33%) increased. Chitosan insect films showed lower TS and EM, and higher WPV, %E and solubility than commercial films. SEM revealed that chitosan insect films had lower porosity than commercial films. FTIR and X-ray diffraction showed not difference between insect and commercial chitosan films. These results showed that T. molitor and B. magna chitosan films could be used as a packaging material in several food products.

Identification and Functional Characterization of a Fructooligosaccharides-Forming Enzyme from Aspergillus aculeatus.

Although fructosyltransferases from Aspergillus aculeatus have received a considerable interest for the prebiotics industry, their amino acid sequences and structural features remain unknown. This study sequenced and characterized a fructosyltransferase from A. aculeatus (AcFT) isolated by heat treatment of Pectinex Ultra SP-L. The AcFT enzyme showed two isoforms, low-glycosylated AcFT1 and high-glycosylated AcFT2 forms, with similar optimum activity at 60 °C. The purified heat-resistant AcFT1 and AcFT2 isoforms produced identical patterns of fructooligosaccharides (FOS; kestose, nystose and fructosylnystose) with a notable transfructosylation capability (~90 % transferase/hydrolase ratio). In contrast, the pI and optimum pH values exhibited discrete differences, attributable to their glycosylation pattern. Partial protein sequencing showed that AcFT enzyme corresponds to Aspac1_37092, a putative 654-residue fructosyltransferase encoded in the genome of A. aculeatus ATCC16872. A homology model of AcFT also revealed the typical fold common to members of the glycoside hydrolase family 32 (GH32), with an N-terminal five-blade ß-propeller domain enclosing catalytic residues D60, D191, and E292, linked to a C-terminal ß-sandwich domain. To our knowledge, this is the first report describing the amino acid sequence and structural features of a heat-resistant FOS-forming enzyme from A. aculeatus, providing insights into its potential applications in the prebiotics industry.

Antioxidant activity and content of chlorophylls and carotenoids in raw and heat-processed Jalapeño peppers at intermediate stages of ripening.

Jalapeño peppers at intermediate ripening stages (IRS) are typically discarded at the packinghouse because they are not demanded for fresh consumption or industrial processing. These peppers have been scarcely studied in terms of pigment composition and bioactivity. In this study, the profile of pigments (carotenoids and chlorophylls) and antioxidant activity were determined in raw and heat-processed Jalapeño peppers at three IRS (brown, 50% red, and 75% red). Peppers contained 64 different pigments. Chlorophylls were the most abundant pigments in raw brown peppers while capsanthin was the most abundant at the other IRS. The content of most pigments decreased due to heat treatments. Several pheophytins and cis isomers of carotenoids were generated by heat processing. Boiling and grilling consistently decreased and increased the antioxidant activity of peppers, respectively. Tested peppers showed a more complex/abundant pigment content and higher antioxidant activity than those typically reported for green and red peppers.