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result(s) for
"Hoff, Justin W."
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Characterization of Zalaria obscura Y1223 hydrolases: implications for lignocellulose conversion
by
du Plessis, Heinrich W.
,
Boonzaier, Jeremy J.
,
den Haan, Riaan
in
Agricultural research
,
Agricultural wastes
,
Biodiesel fuels
2025
Overconsumption of fossil fuel reserves and its adverse effects has sparked interest in the production of second-generation biofuels due to the abundance of lignocellulosic waste and potential energy crops. However, processing costs associated with depolymerization of the cellulose crystalline structure have stalled advancement in cellulosic ethanol production. Current investigations range from identification of novel enzymes for lignocellulose hydrolysis to consolidation of enzyme production into a singular alcohol producing microorganism to potentially reduce cost for commercial processing. In this study, a total of 828 non-
Saccharomyces
and black yeasts were screened for cellulolytic and xylanolytic enzyme activities, whereby 60 isolates were identified that exhibited activity for at least one of the enzymes tested. In doing so, a novel
Zalaria obscura
strain (
Z. obscura
Y1223) was identified and assessed for enzyme activity in multiple growth media. Semi-quantitative assays showed that
Z. obscura
Y1223 produced cellulases optimally in media containing yeast extract, peptone and oat bran, with a pH range between pH 5 and 6 and at 30 °C. Maximum xylanase activity (20.5 U/L/OD
600
) was attained using synthetic complete media supplemented with xylo-oligosaccharides and maximum cellulase activity (7.51 U/L/OD
600
endoglucanase, 1.302 U/L/OD
600
β-glucosidase) was attained when grown in media containing yeast extract, peptone and oat bran. To our knowledge, this is the first study to quantify the cellulolytic and xylanolytic enzyme activities of a
Zalaria
spp., which provides key insight into the availability of unexplored cellulolytic enzymes that could inform the design of organisms engineered for consolidated bioprocessing.
Journal Article
Impact of Yeast Selection on Volatile Phenol Levels of Wines Produced from Smoked-Exposed Juice
by
Mokwena, Lucky
,
van der Rijst, Marieta
,
du Plessis, Heinrich W.
in
alcoholic fermentation
,
chemical analyses
,
Fermentation
2021
Grapes exposed to smoke can result in wines that have unacceptable high levels of volatile phenols. High volatile phenols levels have a negative impact on wine quality. This study aimed to determine the levels of volatile phenols in wines produced from smoke-exposed juice by a selection of commercial wine yeasts and to determine if yeast selection affected the perception of smokiness in wine. Commercial white and red wine yeasts were screened for the production of volatile phenols in smoke-exposed Chenin Blanc and Merlot juice. Volatile phenol levels were determined by GC-MS/MS and wines were also subjected to sensory evaluation. Volatile phenol levels in smoked wines varied and was affected by yeast strain. The highest guaiacol levels in Chenin Blanc were found in wines fermented with QA23, while Merlot wines that underwent spontaneous alcoholic fermentation contained the highest levels. The levels of volatile phenols differed significantly between the smoked and unsmoked wines, and the sensory results supported the chemical data. Volatile phenols had a negative effect on Chenin Blanc flavor profiles even when the levels were below odor detection thresholds. Yeast selection is important and can affect the volatile phenol levels and flavor profiles of wines.
Journal Article
Finding the missing honey bee genes: lessons learned from a genome upgrade
by
Hoff, Katharina Jasmin
,
Weaver, Daniel B
,
Evans, Jay D
in
Animal Genetics and Genomics
,
Animals
,
Apis mellifera
2014
Background
The first generation of genome sequence assemblies and annotations have had a significant impact upon our understanding of the biology of the sequenced species, the phylogenetic relationships among species, the study of populations within and across species, and have informed the biology of humans. As only a few Metazoan genomes are approaching finished quality (human, mouse, fly and worm), there is room for improvement of most genome assemblies. The honey bee (
Apis mellifera
) genome, published in 2006, was noted for its bimodal GC content distribution that affected the quality of the assembly in some regions and for fewer genes in the initial gene set (OGSv1.0) compared to what would be expected based on other sequenced insect genomes.
Results
Here, we report an improved honey bee genome assembly (Amel_4.5) with a new gene annotation set (OGSv3.2), and show that the honey bee genome contains a number of genes similar to that of other insect genomes, contrary to what was suggested in OGSv1.0. The new genome assembly is more contiguous and complete and the new gene set includes ~5000 more protein-coding genes, 50% more than previously reported. About 1/6 of the additional genes were due to improvements to the assembly, and the remaining were inferred based on new RNAseq and protein data.
Conclusions
Lessons learned from this genome upgrade have important implications for future genome sequencing projects. Furthermore, the improvements significantly enhance genomic resources for the honey bee, a key model for social behavior and essential to global ecology through pollination.
Journal Article
Pan-Filovirus Serum Neutralizing Antibodies in a Subset of Congolese Ebolavirus Infection Survivors
by
Wemakoy, Emile Okitolonda
,
Doshi, Reena H
,
Logue, James
in
Antibodies, Monoclonal
,
Antibodies, Neutralizing - blood
,
Antibodies, Viral - blood
2018
One year after a Zaire ebolavirus (EBOV) outbreak occurred in the Boende Health Zone of the Democratic Republic of the Congo during 2014, we sought to determine the breadth of immune response against diverse filoviruses including EBOV, Bundibugyo (BDBV), Sudan (SUDV), and Marburg (MARV) viruses. After assessing the 15 survivors, 5 individuals demonstrated some degree of reactivity to multiple ebolavirus species and, in some instances, Marburg virus. All 5 of these survivors had immunoreactivity to EBOV glycoprotein (GP) and EBOV VP40, and 4 had reactivity to EBOV nucleoprotein (NP). Three of these survivors showed serologic responses to the 3 species of ebolavirus GPs tested (EBOV, BDBV, SUDV). All 5 samples also exhibited ability to neutralize EBOV using live virus, in a plaque reduction neutralization test. Remarkably, 3 of these EBOV survivors had plasma antibody responses to MARV GP. In pseudovirus neutralization assays, serum antibodies from a subset of these survivors also neutralized EBOV, BDBV, SUDV, and Taï Forest virus as well as MARV. Collectively, these findings suggest that some survivors of naturally acquired ebolavirus infection mount not only a pan-ebolavirus response, but also in less frequent cases, a pan-filovirus neutralizing response.
Journal Article
Variance component estimates, phenotypic characterization, and genetic evaluation of bovine congestive heart failure in commercial feeder cattle
2023
The increasing incidence of bovine congestive heart failure (BCHF) in feedlot cattle poses a significant challenge to the beef industry due to economic loss, reduced performance, and reduced animal welfare attributed to cardiac insufficiency in growing animals. Changes to cardiac morphology as well as abnormal pulmonary arterial pressure (PAP) in purebred cattle of mostly Angus ancestry have been extensively characterized over the past 30 years. However, congestive heart failure affecting cattle late in the feeding period has been an increasing problem over time and tools are needed for the industry to address the rate of mortality in the feedlot. At harvest, a population of 32,763 commercial fed cattle was phenotyped for cardiac morphology with associated production data collected from feedlot processing to harvest at a single feedlot and packing plant in the Pacific Northwest. A sub-population of 5,001 individuals were selected for low-pass genotyping to estimate variance components and genetic correlations between heart score and the production traits observed during the feeding period. At harvest, the incidence of a heart score of 4 or 5 in this population was approximately 4.14%, indicating a significant proportion of feeder cattle are at an increased risk of cardiac mortality before harvest. The heart scores were also significantly and positively correlated with the percentage Angus ancestry observed by genomic breed percentage analysis. The heritability of heart score measured as a binary (scores 1 and 2 = 0, scores 4 and 5 = 1) trait was 0.356 in this population, which indicates the development of a selection tool to reduce the risk of congestive heart failure in the form of an EPD (expected progeny differences) is feasible. Genetic correlations of heart score with growth traits and feed intake were moderate and positive (0.289 to 0.460). Genetic correlations between heart score and backfat and marbling score were -0.120 and -0.108, respectively. Significant genetic correlation to traits of high economic importance in existing selection indexes may explain the increased rate of congestive heart failure observed over time. These results indicate there is potential to implement heart score observed at harvest as a phenotype under selection in genetic evaluation in order to reduce feedlot mortality due to cardiac insufficiency and improve overall cardiopulmonary health in feeder cattle.Competing Interest StatementThe authors have declared no competing interest.