Sensory Attributes and Chemical Composition: The Case of Three Monofloral Honey Types from Algeria.

There is a demand from the scientific, beekeeping and consumer sectors to characterize honey based on its botanical origin, as it provides unique and distinctive properties. Nevertheless, existing studies on the physicochemical properties and the sensorial profile of honey in relation to botanical origin remain insufficient. This study aimed to understand the relationships between sensory profile and various chemical compounds (minerals, sugars, water content and volatiles) of three monofloral honeys (Atractylis serratuloides, Retama sphaerocarpa and Eruca sativa) produced in Algeria using principal component analysis. Crystallization was detected as a distinctive attribute of Eruca and Atractylis honey. A candy aroma and odor with floral nuances, light color, crystallized state and the volatile compounds Alpha-Bisabolol and Beta-eudesmol characterized the Atractylis honey. Eruca honeys were distinguished by an animal and degraded odor, bitter taste, light color and the presence of Dimethyl trisulfide and Dimethyl tetrasulfide. Finally, a vegetal aroma, some saltiness and sourness, dark amber color, lower sugar content, higher K content and Lilac aldehyde and Lilac aldehyde D characterized Retama honeys.

The Contribution of Botanical Origin to the Physicochemical and Antioxidant Properties of Algerian Honeys.

Honeys from different regions of Algeria were analyzed to determine their pollen characteristics and physicochemical properties (humidity, pH, electrical conductivity, diastase content, color, phenols, flavonoids and antioxidant activity). The antioxidant activity was investigated using the free radical scavenging and Ferric reducing/antioxidant power assays. The melissopalynological analysis revealed 129 pollen types from 53 botanical families. The pollen types found as dominant were Coriandrum, Bupleurum, Brassica napus type, Hedysarum coronarium, Ceratonia siliqua, Eucalyptus, Peganum harmala, Ziziphus lotus and Tamarix. Principal component analysis and cluster analysis were used to analyze significant relationships between the physicochemical variables and the botanical origin of the honeys and establish groupings based on the similarities of their physicochemical and antioxidant properties. The results showed that Ceratonia siliqua, Eucalyptus, Arbutus and honeydew honeys had a higher antioxidant contribution and higher phenolic and flavonoid contents than the rest of the honeys. In addition, the contributions of Mediterranean vegetation such as Myrtus and Phyllirea angustifolia were significant in this honey group. This paper demonstrates the diverse botanical variability for honey production in Algeria. However, there is a gap in its characterization based on its botanical origin. Therefore, these studies contribute positively to the needs of the beekeeping sector and the commercial valorization of the country's honey.

Industrial Processing of Algerian Table Olive Cultivars Elaborated as Spanish Style.

Olives from the Sigoise, Verdale, and Sevillana cultivars were elaborated as Spanish-style table olives by four Algerian factories, and the quality and food safety of the industrial table olives have been studied by the analysis of physicochemical and microbiological parameters. Differences were observed between the treatments carried out by the different factories throughout the manufacturing process, especially during the washing stage, but no significant differences were found between the analyzed samples for the concentration of sugars and polyphenols. The final pH values reached at the end of fermentation ranged between 5.04 and 4.27, and the titratable acidity was above 0.4% for all samples. Lactic and acetic acids were produced in mean concentrations of 0.68% and 0.21% as a result of lactic acid bacteria (LAB) and yeast metabolism, respectively. However, the presence of butyric, isobutyric, and propionic acids was also detected, and was related to the growth of undesirable spoilage microorganisms, responsible for secondary fermentations. The high-throughput sequencing of bacterial DNA suggested the dominance of LAB species belonging to genera Lactiplantibacillus, Leuconostoc, Pediococcus, Oenococcus, or Enterococcus. The Enterobacteriaceae family was detected during the first days of brining and in only one sample after 120 days of fermentation. Other spoilage microorganisms were found, such as Lentilactobacillus buchneri or the Pectinatus and Acetobacter genera, capable of consuming lactic acid and these played an essential role in the onset of spoilage. The Clostridium and Enterobacter genera, producers of butyric and propionic acids, were responsible for the malodorous fermentation present in the industrial samples that were analyzed. The study concluded that the safety of the table olives analyzed was compromised by the presence of undesirable microorganisms and microbial stability was not guaranteed. The elaboration process can be improved by reducing the washing steps and the time should be reduced to avoid the loss of fermentable matter, with the goal of reaching a pH < 4.0 after the fermentation and preventing the possibility of the growth of spoilage microorganisms and foodborne pathogens.

Biochemical and molecular characterization of an acido-thermostable endo-chitinase from Bacillus altitudinis KA15 for industrial degradation of chitinous waste.

This paper reports the isolation and identification of an acido-thermostable chitinase (ChiA-Ba43) which was purified, from the culture liquid of Bacillus altitudinis strain KA15, and characterized. Purification of ChiA-Ba43 produced a 69.6-fold increase in the specific activity (120,000 U/mg) of the chitinase, with a yield of 51% using colloidal chitin as substrate. ChiA-Ba43 was found to be a monomeric protein with a molecular mass of 43,190.05 Da as determined by MALDI-TOF/MS. N-terminal sequence of the first 27 amino-acids (aa) of ChiA-Ba43 displayed homology to chitinases from other Bacillus species. Interestingly, ChiA-Ba43 exhibited optimum pH and temperature of 4-5.5 and 85 °C, respectively. Thin-layer chromatography (TLC) showed that the final hydrolyzed products of the enzyme from chitin-oligosaccharides and colloidal chitin are a mixture of (GlcNAc)2, (GlcNAc)3, (GlcNAc)4, and (GlcNAc)5, which indicates that ChiA-Ba43 possesses an endo-acting function. More interestingly, compared to ChiA-Mt45, ChiA-Hh59, Chitodextrinase®, N-acetyl-ß-glucosaminidase®, and ChiA-65, ChiA-Ba43 demonstrated a high level of catalytic efficiency and outstanding tolerance towards various organic solvents. The chiA-Ba43 gene (1332 bp) encoding ChiA-Ba43 (409 aa) was cloned, sequenced, and expressed in Escherichia coli strain HB101. The biochemical properties of the recombinant chitinase (rChiA-Ba43) were equivalent to those of the natively expressed enzyme. These properties make ChiA-Ba43 an ideal candidate for industrial bioconversion of chitinous waste.

Identification and homology modeling of a new biotechnologically compatible serine alkaline protease from moderately halotolerant Gracilibacillus boraciitolerans strain LO15.

A new serine alkaline protease (designated as SAPGB) from Gracilibacillus boraciitolerans strain LO15, was produced (9000 U/mL), purified, and characterized. SAPGB has a monomer structure with a precise molecular weight of 30,285.03 kDa as learnt from matrix-assisted laser desorption/ionization-time of flight/mass spectroscopy (MALDI-TOF/MS) exploration. The NH2-terminal amino-acid succession revealed significant identity with Bacillus proteases. The SAPGB was irreversibly inhibited by diiodopropyl fluorophosphates (DFP) and phenylmethylsulfonyl fluoride (PMSF). The enzyme displayed optimum activity at 65 °C and pH 10. The maximal activity was achieved in the range 0.5-5 M NaCl and about 52% of the activity was preserved across the broad salinity range of 0-30%. SAPGB exhibited a considerable catalytic efficiency (ratio kcat/Km) and degree of hydrolysis (DH). In addition, SAPGB showed a high tolerance to several organic solvents and an excellent detergent compatibility than SAPV, SAPA, Thermolysin type X, and Esperase 8.0 L. These properties make SAPGB a potential candidate for detergent formulations. On the other hand, sapGB gene was cloned and expressed in E. coli BL21(DE3)pLysS and the biochemical properties of the purified extracellular recombinant protease (rSAPGB) were similar to those of SAPGB. Finally, a 3D structural model of SAPGB was constructed by homology modeling.

Receptor-like protein kinase HvLysMR1 of barley (Hordeum vulgare L.) is induced during leaf senescence and heavy metal stress.

The Hordeum vulgare cDNA clone HvLysMR1 that encodes a putative receptor-like protein kinase was identified by restriction fragment differential display-polymerase chain reaction (PCR) comparing cDNA populations derived from mRNAs of primary leaves stressed with chromium for 48 h with controls. The full-length sequence codes for a protein with 622 amino acids which includes characteristic domains of lysine motif receptor-like kinases: an N-terminal signal peptide, two lysine motifs, a transmembrane region, and a serine/threonine kinase domain at the C-terminal end. The expression of HvLysMR1 is induced during exposure to different heavy metals and its transcript accumulates during leaf senescence. Addition of the calcium ionophore A23187 induces HvLysMR1 expression, indicating the involvement of Ca2+ in the regulation of HvLysMR1. In vitro phosphorylation of HvLysMR1 was analysed with [32P]ATP. Using the overexpressed and purified HvLysMR1-kinase domain, the phosphorylation of HvLysMR1 could be confirmed by nano-liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) with neutral loss-triggered MS-MS-MS spectra at amino acids localized at the juxtamembrane region. The involvement of HvLysMR1 during heavy metal stress and leaf senescence is discussed.

Involvement of Arabidopsis prolyl 4 hydroxylases in hypoxia, anoxia and mechanical wounding.

Arabidopsis prolyl 4 hydroxylases (P4Hs) catalyze an important post-translational modification in plants, though the only information on their patterns of expression is solely based on Arabidopsis microarray analysis data. In addition, the expression patterns of plants P4Hs in response to hypoxia, anoxia and other abiotic stresses such as mechanical wounding have never been studied extensively, despite their central role in hypoxic response of several other organisms through the regulation of stability of the HIF-1alpha transcription factor, the global regulator of hypoxic response. The 13 putative Arabidopsis P4Hs are low abundance transcripts with differential patterns of expression in response to two hypoxic, 1.5% and 5% O(2), anoxic conditions and mechanical wounding. Hypoxia of 1.5% O(2) induced the expression of six At-P4Hs while hypoxia of 5% O(2) and anoxia induced the expression of three and two At-P4Hs, respectively. Moreover, 308 Arabidopsis genes including 25 transcription factors were identified in silico among the differentially expressed genes under hypoxia that contain proline hydroxylation motifs. These results suggest involvement of this post-translational modification in the processing of hypoxia induced proteins providing an alternative level of regulation for responses to oxygen deficiency conditions.

Heavy metal stress and leaf senescence induce the barley gene HvC2d1 encoding a calcium-dependent novel C2 domain-like protein.

By comparing cDNA populations derived from chromium-stressed primary leaves of barley (Hordeum vulgare L.) with controls, differentially expressed cDNA fragments could be identified. The deduced amino acid sequence of one of these cDNAs [named 'C2 domain 1' (HvC2d1)] exhibits a motif that is similar to the known C2 domain and a nuclear localization signal (NLS). Expression of this member of a novel class of plant C2 domain-like proteins was studied using real-time PCR, and subcellular localization was investigated using green fluorescent protein (GFP) fusion constructs. Calcium binding was analysed using a (45)Ca(2+) overlay assay. HvC2d1 was transiently induced after exposure to different heavy metals and its mRNA accumulated during the phase of leaf senescence. HvC2d1 expression responded to changes in calcium levels caused by the calcium ionophore A23187 and to treatment with methylviologen resulting in the production of reactive oxygen species (ROS). Using overexpressed and purified HvC2d1, the binding of calcium could be confirmed. Chimeric HvC2d1-GFP protein was localized in onion epidermal cells at the plasma membrane, cytoplasm and the nucleus. After addition of calcium ionophore A23187 green fluorescence was only visible in the nucleus. The data suggest a calcium-dependent translocation of HvC2d1 to the nucleus. A possible role of HvC2d1 in stress- and development-dependent signalling in the nucleus is discussed.