Sherry Fillmore

Antimicrobial activity of bacteriocin-producing lactic acid bacteria isolated from cheeses and yogurts

The biopreservation of foods using bacteriocinogenic lactic acid bacteria (LAB) isolated directly from foods is an innovative approach. The objectives of this study were to isolate and identify bacteriocinogenic LAB from various cheeses and yogurts and evaluate their antimicrobial effects on selected spoilage and pathogenic microorganisms in vitro as well as on a food commodity.LAB were isolated using MRS and M17 media. The agar diffusion bioassay was used to screen for bacteriocin or bacteriocin-like substances (BLS) producing LAB using Lactobacillus sakei and Listeria innocua as indicator organisms. Out of 138 LAB isolates, 28 were found to inhibit these bacteria and were identified as strains of Enterococcus faecium, Streptococcus thermophilu s, Lactobacillus casei and Lactobacillus sakei subsp. sakei using 16S rRNA gene sequencing. Eight isolates were tested for antimicrobial activity at 5°C and 20°C against L. innocua, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, Erwinia carotovora, and Leuconostoc mesenteroides subsp. mesenteroides using the agar diffusion bioassay, and also against Penicillium expansum, Botrytis cinerea and Monilinia frucitcola using the microdilution plate method. The effect of selected LAB strains on L. innocua inoculated onto fresh-cut onions was also investigated.Twenty percent of our isolates produced BLS inhibiting the growth of L. innocua and/or Lact. sakei. Organic acids and/or H2O2 produced by LAB and not the BLS had strong antimicrobial effects on all microorganisms tested with the exception of E. coli. Ent. faecium, Strep. thermophilus and Lact. casei effectively inhibited the growth of natural microflora and L. innocua inoculated onto fresh-cut onions. Bacteriocinogenic LAB present in cheeses and yogurts may have potential to be used as biopreservatives in foods.

Anthocyanin metabolites are abundant and persistent in human urine.

LC-MS/MS revealed that metabolites of anthocyanins (Acn) were abundant in human urine (n = 17) even after 5 days with no dietary Acn. After intake of 250 mL of blueberry juice, parent Acn were 4% and Acn metabolites were 96% of the total urinary Acn for the following 24 h. Multiple reaction monitoring revealed 226 combinations of mass transition × retention times for known Acn and predicted Acn metabolites. These were dominated by aglycones, especially aglycone glucuronides. The diversity of Acn metabolites could include positional isomers of Acn conjugates and chalcones. The persistence of Acn metabolites suggested enterohepatic recycling leading to prolonged residence time. The prevalence of Acn metabolites based on pelargonidin, which is not present in blueberry juice, may reflect ongoing dehydroxylation and demethylation of other Acn via xenobiotic and colonic bacterial action. The results suggest that exposure to Acn-based flavonoid moieties is substantially greater than suggested by earlier research.

Ethylene and 1-MCP regulate major volatile biosynthetic pathways in apple fruit

The effects of ethylene and 1-methylcyclopropene (1-MCP) on apple fruit volatile biosynthesis and gene expression were investigated. Statistical analysis identified 17 genes that changed significantly in response to ethylene and 1-MCP treatments. Genes encoding branched-chain amino acid aminotransferase (BCAT), aromatic amino acid aminotransferase (ArAT) and amino acid decarboxylases (AADC) were up-regulated during ripening and further enhanced by ethylene treatment. Genes related to fatty acid synthesis and metabolism, including acyl-carrier-proteins (ACPs), malonyl-CoA:ACP transacylase (MCAT), acyl-ACP-desaturase (ACPD), lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC2), β-oxidation, acyl-CoA synthetase (ACS), enoyl-CoA hydratase (ECHD), acyl-CoA dehydrogenase (ACAD), and alcohol acyltransferases (AATs) also increased during ripening and in response to ethylene treatment. Allene oxide synthase (AOS), alcohol dehydrogenase 1 (ADH1), 3-ketoacyl-CoA thiolase and branched-chain amino acid aminotransferase 2 (BCAT2) decreased in ethylene-treated fruit. Treatment with 1-MCP and ethylene generally produced opposite effects on related genes, which provides evidence that regulation of these genes is ethylene dependent.

Blueberry and cranberry fruit composition during development

Compositional changes that occur during fruit development affect both the organoleptic and nutritional quality of small fruit. Compositional changes in blueberry (Vaccinium corymbosum L) and cranberry (Vaccinium macrocarpon Aiton) fruit were determined at 3 maturities (white, turning and fully colored) during 2 seasons by analyzing sugar, acid, total phenolic, and total anthocyanin composition, ORAC antioxidant capacity, and fruit firmness. In blueberry fruit, the primary sugars were glucose and fructose, which increased as fruit ripened. Citric acid comprised 77 to 87% of the organic acids in blueberry fruit. In addition, quinic and malic acids comprised 4 to 11% of total acids and small amounts of succinic, tartaric, and shikimic acids were present. Total acids declined 68% during fruit ripening. Total phenolics were greatest in white fruit and anthocyanins were greatest in blue fruit. Antioxidant capacity declined as fruit ripened from white to turning. Fruit firmness decreased about 80% as fruit ripened. In cranberry fruit, sugar concentration increased slightly as fruit ripened with glucose comprising about 80% of the total sugars. Acid content decreased 22% during ripening primarily due to a decline in citric acid. Quinic and malic acids increased slightly during ripening. Total anthocyanins increased as color developed, while total phenolics and antioxidant capacity remained relatively constant. In contrast to blueberries, red cranberry fruit were firmer than white or turning fruit.

Nova Scotia Wild Blueberry Soil and Leaf Nutrient Ranges

Soil and leaf samples were collected from 44 wild blueberry fields throughout Nova Scotia in 1989–90 and in 1997–98, and analyzed for macro- and micronutrient content. Samples were obtained from sprout fields, in late July and early August, after terminal dieback of terminal leaf buds. Soil and tissue concentrations of P and K were increased by repeated fertilizer applications between the two sample periods, whereas soil pH was decreased. Leaf tissue concentrations of P, Cu, B, Zn and Fe were consistently lower than indicated by the Trevett standards, suggesting that a separate set of nutrient ranges should be adopted for Nova Scotia wild blueberry fields.

Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources

Sharifi, M., Cheema, M., Mahoney, K., LeBlanc, L. and Fillmore, S. 2013. Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources. Can. J. Plant Sci. 93: 1209-1216. Wood ash has the potential to enhance productivity in agricultural systems by influencing soil pH and nutrient availability. The liming properties and fertility values of wood ash from three Atlantic wood ash sources were evaluated in this study. The liming properties were tested using three wood ash sources [JD Irving (IR), New Page (NP), and Brooklyn Power (BP)] and two local lime sources in an 8-mo incubation experiment at 25°C. Soil pH was measured 14 times during the incubation. Availability of potassium (K) in wood ash was evaluated in a greenhouse setting with a K-deficient soil using annual ryegrass as the test plant. Total plant K and P uptake and Mehlich-3 extractable K and P were used as predictors of nutrient bioavailability. Wood ash application increased soil pH to the maximum level within the first 50 d after application and stabilized soil pH for 8 mo. The measured effective calcium carbonate equivalent of ashes relative to Mosher lime average among two soils were in order of BP (32)>IR (25)>NP (16). About 96, 38, and 71% of total K in IR, NP and BP ash sources, respectively, were bioavailable for ryegrass in 115 d. Although soil was not P deficient, soil P bioavailability (Mehlich III extractable P) was enhanced by 14 and 48% in NP and BP wood ash treatments, respectively, whereas P bioavailability decreased by 24% in the IR ash treatment. The results clearly demonstrate that these sources of wood ash can be considered as an effective liming agent and source of K in agricultural production systems.

Herbage yield and composition of Kentucky bluegrass (Poa pratensis L.) cultivars under two harvest systems

Although Kentucky bluegrass (Poa pratensis L.) is a naturalized species commonly found in the permanent grasslands of eastern Canada, its contribution to sward output is not well defined. Six Kentucky bluegrass cultivars originating from Norway, Germany and North America, and a timothy (Phleum pratense L.) cultivar, were grown under two harvest systems at two locations to determine yield and herbage composition. All cultivars persisted over 3 production years. Dry matter yields of bluegrass cultivars were similar to those of timothy, ranging from 7.87 to 9.76 t ha-1 in Charlottetown, Prince Edward Island, and from 3.64 to 4.79 t ha-1 in Normandin, Quebec. Yields of broadleafed genotypes from Europe were superior in year 1. However, the warm and dry growing conditions of year 3 favoured the narrow-leafed genotypes. Mean tiller density of Kentucky bluegrass was 6440 m-2; timothy had a mean tiller density of 3040 m-2. Forage quality attributes of Kentucky bluegrass were similar to those of timothy. Cultivar ...

Yield, herbage composition, and tillering of timothy cultivars under grazing

Timothy is widely grown for silage and hay in eastern Canada. The relative performance of timothy cultivars under grazing is not, however, well documented. This research determined dry matter production, herbage composition, and tiller characteristics of 34 timothy cultivars under two grazing schedules over 3 yr on the same plots. Several cultivars outyielded the standard cultivar, Farol (7.96 t ha-1), by up to 10% for the 3-yr mean. Richmond and Comtal were the highest-yielding cultivars (8.75 t ha-1) while AC Regal had the best relative yield persistence over the experimental period. Crude protein concentrations of cultivars ranged from 172 to 208 g kg-1 for early and 150 to 179 g kg-1 for late grazing. Neutral detergent fibre (NDF) concentrations ranged from 460 to 495 g kg-1 and concentration of acid detergent fibre (ADF) ranged from 241 to 270 g kg-1 among the cultivars in early grazing. Differences in NDF and ADF concentrations between early and late grazing schedules varied among the cultivars indi...

Quantitative changes in proteins responsible for flavonoid and anthocyanin biosynthesis in strawberry fruit at different ripening stages: A targeted quantitative proteomic investigation employing multiple reaction monitoring.

UNLABELLED To better understand the regulation of flavonoid and anthocyanin biosynthesis, a targeted quantitative proteomic investigation employing LC-MS with multiple reaction monitoring was conducted on two strawberry cultivars at three ripening stages. This quantitative proteomic workflow was improved through an OFFGEL electrophoresis to fractionate peptides from total protein digests. A total of 154 peptide transitions from 47 peptides covering 21 proteins and isoforms related to anthocyanin biosynthesis were investigated. The normalized protein abundance, which was measured using isotopically-labeled standards, was significantly changed concurrently with increased anthocyanin content and advanced fruit maturity. The protein abundance of phenylalanine ammonia-lyase; anthocyanidin synthase, chalcone isomerase; flavanone 3-hydroxylase; dihydroflavonol 4-reductase, UDP-glucose:flavonoid-3-O-glucosyltransferase, cytochrome c and cytochrome C oxidase subunit 2, was all significantly increased in fruit of more advanced ripeness. An interaction between cultivar and maturity was also shown with respect to chalcone isomerase. The good correlation between protein abundance and anthocyanin content suggested that a metabolic control point may exist for anthocyanin biosynthesis. This research provides insights into the process of anthocyanin formation in strawberry fruit at the level of protein concentration and reveals possible candidates in the regulation of anthocyanin formation during fruit ripening. BIOLOGICAL SIGNIFICANCE To gain insight into the molecular mechanisms contributing to flavonoids and anthocyanin biosynthesis and regulation of strawberry fruit during ripening is challenging due to limited molecular biology tools and established hypothesis. Our targeted proteomic approach employing LC-MS/MS analysis and MRM technique to quantify proteins in relation to flavonoids and anthocyanin biosynthesis and regulation in strawberry fruit during fruit ripening is novel. The identification of peptides and proteins provided reliable design and validation of quantitative approaches using SRM on targeted proteins proposed involved in strawberry fruit. Our data revealed the identifying candidate proteins and their quantitative changes in relation to fruit ripening and flavonoids and anthocyanin biosynthesis and regulation. More importantly, this quantitative proteomic data is also compared with chemical analysis to reveal possible control levels of this important quality trait. Although, MRM approach is not new in plant biology research, the application has been very rare. This is the first systematic multi-targeted interrogation of the possible regulation of entire pathway of flavonoids and anthocyanin biosynthesis in strawberry fruit at different ripening stages using quantitative MRM technique on mass spectrometry. Our results demonstrate the power of targeted quantitative mass spectrometry data for analysis of proteins in biological regulation. These results indicate that distinct and diverse control of flavonoids and anthocyanin biosynthesis mechanisms at metabolism and proteins levels. This important and complementary knowledge will be useful for systematically characterizing the flavonoids and anthocyanin biosynthesis pathway of any fruit/plant species.

Effect of rotational grazing on selected physical properties of a Gleyed Brunisolic Gray Luvisol loam in Nova Scotia

Low organic matter content and weak soil structure, combined with high annual precipitation, make the soils of the Maritime Provinces extremely susceptible to compaction. Although many pasture studies have been conducted in the Maritime Provinces, none has investigated the impact of pasturing cattle on soil physical properties. Soil properties such as resistance to penetration, bulk density and hydraulic conductivity were monitored on pasture swards receiving various rotational-grazing intensities. These parameters were measured concomitantly on traffic-free areas that had been harvested as conserved forage. Resistance to penetration measurements indicate that a significant amount of compaction by cattle occurred during the 1990, 1991 and 1992 grazing seasons. Penetration resistance was generally greatest in the top 6 cm of soil, but was alleviated by frost action during the subsequent winter and spring. The other soil parameters measured were either more variable (surface and subsurface saturated hydraul...