Peer-Reviewed Publications

The effects of high pressure processing (HPP) at 200, 300, 400, 500, and 600 MPa for 3 min on physicochemical quality and inactivation of microbial loads of Asian hard clam (Meretrix lusoria) were evaluated. In addition, the retardation effects in microbial growth and quality loss of pressurized hard clams stored at 4 °C were investigated. Results showed that the expanding rate, moisture content, shucking ratio, pH, L* (lightness), and W (whiteness) of clam meat increased significantly with the increase in pressure, but a* (redness) and b* (yellowness) values decreased. With the increase in pressure, the levels of aerobic plate count (APC), psychrotrophic bacteria count (PBC), coliform, and Vibrio parahaemolyticus in clam meat significantly decreased. Furthermore, HPP with a pressure of >400 MPa on clam samples significantly delayed the increase in APC (by 6–9 days within Taiwan's regulation standard limit) and PBC during storage at 4 °C. However, the samples pressurized more than 300 MPa had significantly lower levels of total volatile basic nitrogen (TVBN) than control samples during storage. Overall, the results indicated that pressurization at least 400 MPa for 3 min on Asian hard clam were able to reach the highest expanding rate and moisture content, and 100 % shucking, while it can reduce the coliform, and V. parahaemolyticus to a non-detectable level. In addition, HPP conditions of ≥400 MPa for 3 min significantly extended the shelf-life of hard clam during refrigerated storage. Therefore, HPP is a useful technique to preserve Asian hard clam meats due to its ability to reduce bacterial load and retard TVBN production. © 2021 Elsevier Ltd

Understanding environmental constraints and associated physiological adaptations of culture organisms is key for the implementation of off-shore grow-out facilities. In the southeast Pacific Ocean along the coasts of Chile and Peru, seasonal upwelling events lead to hypoxic conditions, which are projected to increase in both frequency and intensity with climate change. Aquaculture operations must take into account the physiological adaptability of a species for environmental conditions. For Cojinoba (Seriolella violacea), a native target species for aquaculture diversification in northern Chile, little is known in regard to physiological capacity for hypoxia. Therefore, hypoxia tolerance studies were conducted followed by measurement of resting and active metabolism and associated energy facilitation in response to hypoxia in juvenile Cojinoba. Hypoxia tolerance studies found they were resilient to dissolved oxygen levels of 1.0 mg O2 Lˉ1 for 8 h. Swimming metabolism studies exposed Cojinoba to normoxia (7.5 mg O2 Lˉ1) or hypoxia (1.0 mg O2 Lˉ1), and quantified minimum metabolic rate (MO2 min), active metabolic rate (MO₂ max), critical swimming speed (Ucrit) and associated energetic metabolites and hematological variables. In hypoxia, there was a decrease in MO₂ max (34%) leading to a large (82%) decrease in aerobic metabolic scope. MO2 min decreased as well by 12%, with lactate increasing presumably to temporarily maintain basic metabolic function. In addition, Ucrit decreased by 53% in hypoxia, although tail beat frequency was similar in normoxia and hypoxia up to a velocity of 40 cm s−1. Moreover, although erythrocyte concentration increased in hypoxia, hemolysis was observed in exercised fish in this condition. There was a notable increase (5-fold compared to normoxia) in lactate levels of exercised fish in the hypoxia group, which suggests a quick conversion to anaerobic metabolic pathways to maintain energy balance when swimming in hypoxic environments. Therefore, Cojinoba have adaptive responses that may facilitate survival during severe hypoxic events although overall physiological performance is diminished. © 2021

Two soybean varieties (yellow and black) were ground under three temperature regimes (cold, ambient and hot) and then the raw soymilk underwent three thermal treatments (traditional stove cooking, one-phase ultra-high temperature (UHT) processing, and two-phase UHT processing). Trypsin inhibitor activity (TIA), chymotrypsin inhibitor activity (CIA), total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), DPPH free radical scavenging activity, and oxygen radical absorbing capacity (ORAC) were significantly affected by the above factors and their interactions. For raw yellow soymilk, hot grinding generated 64 and 69% lower TIA than cold and ambient grinding, respectively. For raw black soymilk, hot grinding generated 40 and 43% lower TIA than cold and ambient grinding, respectively. After heating process, the advantage of hot grinding was reduced. By suppression of the development of lipoxygenase-induced hydroperoxides, hot grinding preserved the most sulfhydryl and disulfide groups. Stove cooking following ambient grinding resulted in the lowest CIA. Except TFC, hot grinding recovered the highest phenolic content and antioxidant capacity. CTC from hot grinding was about twice that from ambient grinding. Black soymilk contained significantly higher antioxidant capacity than yellow soymilk and UHT treatments showed advantage over traditional stove cooking in the preservation of phenolics. © 2021 Elsevier Ltd

Recent research within our laboratory has determined the optimal Ross 708 × Ross YP male broiler dIle:dLys ratio for the starter and grower phases to be 70 and 68%, respectively. Thus, the current objective was to continue to re-evaluate the optimal dIle:dLys ratio for this broiler, focusing on the finisher phase. On d of hatch, 2,400 chicks were equally allocated to 96 pens and fed a common starter (d 0–14; 70% dIle:dLys) and grower diet (d 14–28; 68% dIle:dLys). Pen weights were equalized at d 28 by block (12/treatment). Experimental finisher diets (d 28–42;18.0% crude protein, 3,200 kcal/kg, 0.97% dLys, 130% dLeu:dLys) were created from a common deficient (54% dIle:dLys) corn and soybean meal-based diet and contained animal protein. Half of the deficient was retained to create the summit (84% dIle:dLys). The remaining 5 diets were blended proportions of the deficient and summit diets (ranging from 59 to 79% dIle:dLys). A practical control diet (PRAC-CON; 69% dIle:dLys) was manufactured separately to verify the blended control diet (BLEND-CON). All dIle:dLys ratios were estimated using quadratic regression (QR; 95% of the asymptote), as well as linear and quadratic broken line models (LBL; QBL). Feeding equivalent to or slightly lower than current breeder dIle:dLys recommendations (69%) improved broiler performance from d 28 to 42. Based on the current data and multiple regression models, the estimated ratios ranged from 62 to 66% for BW and BWG and 63 to 66% for FCR. Further research should evaluate the optimal dIle:dLys ratio for this broiler throughout the remaining withdrawal phase. © 2021 The Authors

Foodborne pathogens, such as Salmonella are problematic in food processing environments, and understanding the means of persistence is critical in the development of effective control measures. This study determined the antimicrobial tolerance of Salmonella isolates from the processing environment and characterized their biofilm production and antibiotic resistance. Twenty-five Salmonella isolates were previously recovered from poultry processing equipment in commercial production facilities after sanitation. The minimum inhibitory concentration of 2 antimicrobials; chlorine and quaternary ammonium compounds that were frequently used for sanitation was determined for these isolates using the Clinical and Laboratory Standards Institute guidelines. Biofilm forming ability was assessed using the crystal violet assay and antibiotic susceptibility was also determined. These isolates were further characterized based on their genes that were responsible for biofilm formation and resistance to sanitizers and antibiotics. Minimum inhibitory concentration values between 500 and 1,000 parts per million for chlorine, or 3 to 25 parts per million for quaternary ammonium compounds were observed amongst these Salmonella isolates. These isolates possessed strong (24%), moderate (28%), and weak (48%) biofilm forming ability. All isolates were resistant to multiple antibiotics, and 64% exhibited resistance to aminoglycosides and β-lactams. Molecular characterization showed that the isolates possessed specific genes for biofilm formation, sanitizer tolerance, and antibiotic resistance. These results suggest that Salmonella isolates with low tolerance to sanitizers may remain on surfaces because of their strong biofilm forming ability. © 2021 The Authors

Previous research within our laboratory determined the optimal male Ross 708 dIle:dLys ratio for the starter phase to be greater than recent breeder recommendations (70 vs. 67%). Thus, the current objective was to assess the subsequent growth phase (grower) in order to evaluate the optimal dIle:dLys ratio for maximized growth performance of Ross 708 × Ross YP male broilers. On d of hatch, 2,400 chicks were equally allocated to 96 pens and fed a common starter diet. On d 14, pen weights were equalized by block (12 replications/treatments). Experimental grower diets (d 14–28) were created from a common Deficient (53% dIle:dLys) corn and soybean meal-based diet. After batching, half of the Deficient diet was used to create the Summit diet (83% dIle:dLys). The remaining 5 experimental diets ranged from 58 to 78% dIle:dLys and were blended proportions of the Deficient and Summit diets. A practical control diet (PRAC-CON; 68% dIle:dLys) was manufactured separately to verify the blended control diet (BLEND-CON; 68% dIle:dLys). All dIle:dLys ratios were estimated using quadratic regression (QR; 95% of the asymptote), as well as linear and quadratic broken line models (LBL; QBL). Based on the current data and using multiple regression models the estimated ratios ranged from 62 to 68% for BW and BWG, and 67-70% for FCR and are similar to the current breeder nutrient specifications for the grower phase. Further research should evaluate dIle:dLys requirements of male Ross 708 × Ross YP broilers during the remaining grow-out phases. © 2021 The Authors

Streptococcus pneumoniae (pneumococcus) is a normal colonizer of the human nasopharynx capable of causing serious invasive disease. Since colonization of the nasopharynx is a prerequisite for progression to invasive diseases, the development of future protein-based vaccines requires an understanding of the intimate interaction of bacterial adhesins with host receptors. In this study, we identified that pneumococcal surface adhesin A (PsaA), a highly conserved pneumococcal protein known to play an important role in colonization of pneumococcus, can interact with Annexin A2 (ANXA2) on Detroit 562 nasopharyngeal epithelial cells. Lentiviral expression of ANXA2 in HEK 293 T/17 cells, which normally express minimal ANXA2, significantly increased pneumococcal adhesion. Blocking of ANXA2 with recombinant PsaA negatively impacted pneumococcal adherence to ANXA2-transduced HEK cells. These results suggest that ANXA2 is an important host cellular receptor for pneumococcal colonization. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

Upland cotton (Gossypium hirsutum L.) is susceptible to damage by the root-knot and the reniform nematodes, causing yield losses greater than 4% annually in the United States. In addition, these nematodes are synergistic with seeding disease and root rot pathogens that exacerbate diseases and subsequent yield losses. Production practices to minimize nematode damage include crop rotation and nematicides, but these techniques need to be repeated and are expensive. The use of resistant cultivars is deemed the most effective and economical approach for managing nematodes in cotton. Here, we describe the genomes of two nematode-resistant lines of cotton, BARBREN-713 and BAR 32-30. These genomes may expedite the development of DNA markers that can be used to efficiently introduce nematode resistance into commercially valuable Upland lines. © 2021 Genetics Society of America. All rights reserved.

Infections due to Streptococcus pneumoniae, a commensal in the nasopharynx, still claim a significant number of lives worldwide. Genome plasticity, antibiotic resistance, and limited serotype coverage of the available polysaccharide-based conjugate vaccines confounds therapeutic interventions to limit the spread of this pathogen. Pathogenic mechanisms that allow successful adaption and persistence in the host could be potential innovative therapeutic targets. Polyamines are ubiquitous polycationic molecules that regulate many cellular processes. We previously reported that deletion of polyamine transport operon potABCD, which encodes a putrescine/spermidine transporter (∆potABCD), resulted in an unencapsulated attenuated phenotype. Here, we characterize the transcriptome, metabolome, and stress responses of polyamine transport-deficient S. pneumoniae. Compared with the wild-type strain, the expression of genes involved in oxidative stress responses and the nucleotide sugar metabolism was reduced, while expression of genes involved in the Leloir, tagatose, and pentose phosphate pathways was higher in ∆potABCD. A metabolic shift towards the pentose phosphate pathway will limit the synthesis of precursors of capsule polysaccharides. Metabolomics results show reduced levels of glutathione and pyruvate in the mutant. Our results also show that the potABCD operon protects pneumococci against hydrogen peroxide and nitrosative stress. Our findings demonstrate the importance of polyamine transport in pneumococcal physiology that could impact in vivo fitness. Thus, polyamine transport in pneumococci represents a novel target for therapeutic interventions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Bark beetles and root weevils can impact forests through tree death on landscape scales. Recently, subterranean termites have been linked to these beetles via the presence of bluestain fungi (Ascomycota: Ophiostomataceae), which are vectored to trees by beetles. However, only a small subset of bluestain species have been examined. Here, we tested whether termite-bluestain association patterns in the field reflect termite feeding preference in laboratory choice trials. We documented the presence of four bluestain fungi (Leptographium procerum (W.B. Kendr.), L. terebrantis (Barras & Perry), Grosmannia huntii (Rob.-Jeffr.), and G. alacris (T.A. Duong, Z.W. de Beer & M.J. Wingf.) in the roots of 2,350 loblolly pine trees in the southeastern United States and whether termites were present or absent on these roots and paired this with laboratory choice feeding trials. Termites were found 2.5-fold on tree roots with at least one bluestain fungus present than tree roots without bluestain fungi. Although termites in this study and others were associated with L. procerum, L. terebrantis, and marginally G. huntii, termites only showed preferential feeding on wood inoculated with G. huntii in laboratory trials. This suggests that increased termite presence on wood with bluestain fungi may be driven by factors other than increased wood palatability. Termites could thus disproportionately affect wood turnover rates for specific pools (e.g., bark beetle and root weevil attacked trees) and in some cases (e.g., G. huntii) accelerate wood decomposition. This study supports the growing evidence that the association between subterranean termites and bluestain fungi is spatially and taxonomically widespread. Published by Oxford University Press on behalf of Entomological Society of America 2021.

Short-and long-term waterlogging conditions impact crop growth and development, preventing crops from reaching their true genetic potential. Two experiments were conducted using a pot-culture facility to better understand soil waterlogging impacts on corn growth and development. Two corn hybrids were grown in 2017 and 2018 under ambient sunlight and temperature conditions. Waterlogging durations of 0, 2, 4, 6, 8, 10, 12, and 14 days were imposed at the V2 growth stage. Morphological (growth and development) and pigment estimation data were collected 15 days after treatments were imposed, 23 days after sowing. As waterlogging was imposed, soil oxygen rapidly decreased until reaching zero in about 8–10 days; upon the termination of the treatments, the oxygen levels recovered to the level of the 0 days treatment within 2 days. Whole-plant dry weight declined as the waterlogging duration increased, and after 2 days of waterlogging, a 44% and 27% decline was observed in experiments 1 and 2, respectively. Leaf area and root volume showed an exponential decay similar to the leaf and root dry weight. Leaf number and plant height were the least sensitive measured parameters and decreased linearly in both experiments. Root forks were the most sensitive parameter after 14 days of waterlogging in both experiments, declining by 83% and 80% in experiments 1 and 2, respectively. The data from this study improve our understanding of how corn plants react to increasing durations of waterlogging. In addition, the functional relationships generated from this study could enhance current corn simulation models for field applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Class 1 integrons are mobile genetic elements that facilitate the spread of antibiotic resistance genes among bacteria. The use of prophylactic antibiotics has resulted in the rise of antibiotic resistance genes accumulating in a wide range of settings, including poultry houses and the agricultural fields where poultry litter is applied as a fertilizer. Biochar and wood vinegar are forest products wastes that have generated increasing attention as additives to agricultural soils. The objectives of this study were to observe the prevalence of class 1 integrons in poultry litter blended with biochar and wood vinegar over time and to verify a modified class 1 integron screening assay. Poultry litter blends were sampled and screened for class 1 integrons using polymerase chain reaction, and 80 products, 79 of which showed positive, were sent for DNA sequencing. The GenBank® BLAST database was used to verify the presence of the class 1 integron-integrase gene (intI1). There was no change in prevalence over time in poultry litter blends. Out of 79 PCR products that were intI1 positive, 78 showed at least 95% sequence identity to intI1 encoding bacteria and 64 showed at least 97% sequence identity. This indicates that this method was effective for conducting baseline surveillance of class 1 integrons in poultry litter and poultry litter-blended biochar and/or wood vinegar. Most significantly, class 1 integron prevalence did not decrease over time, further supporting the recalcitrance of these elements and the need for improved monitoring systems. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

A tomato plant (Solanum lycopersicum Linnaeus, labelled KVE) displaying virus-like symptoms, tested negative for common tomato viruses, was subjected to high-throughput sequencing (HTS) on the Illumina MiSeq platform using ribosomal RNA-depleted total RNA as a template. The analysis has revealed the contigs mapping to Lettuce big-vein associated virus (LBVaV). The near complete LBVaV-KVE sequence of RNA1 and RNA2 revealed 95.0 and 94.9% identity with the reference sequence, the same length of translated products and a typical varicosavirus genome organisation. After initial long-term maintenance of LBVaV-KVE in the original plant, the virus could be detected by RT-PCR or nanoLC-ESI-Q-TOF in new plants generated from lateral shoot cuttings or inoculated by stem chips, although not uniformly. So far, LBVaV was reported to infect lettuce and related species. Our study expands the natural host range of the LBVaV to tomato. © 2021, Czech Academy of Agricultural Sciences. All rights reserved.

Effects of the in ovo administration of vitamin D3 (D3) and 25-hydroxyvitamin D3 (25OHD3) on broiler intestinal lesion incidence, performance and breast meat yield after a coccidiosis challenge were investigated. On each of 10 incubator tray levels, 10 Ross 708 broiler hatching eggs were randomly assigned to each of the following 5 in ovo injection treatments administrated at 18 d of incubation (doi): 1) noninjected; 2) diluent; diluent containing either 3) 2.4 μg D3 (D3), 4) 2.4 μg 25OHD3 (25OHD3), or 5) 2.4 μg D3 + 2.4 μg 25OHD3 (D3+25OHD3). A 50 μL solution volume was injected into each egg using an Inovoject multi-egg injector. Four male chicks were randomly assigned to each of 80 battery cages in each of 2 rooms. Half of the treatment-replicate cages (8) in each room were challenged with a 20× live coccidial vaccine at 14 d of age (doa). One randomly selected bird from each of 4 treatment-replicate cages was scored for coccidiosis lesions before and 2 wk after challenge. Mean BW, BW gain (BWG), feed intake, and feed conversion ratio were determined for all birds from 0 to 14, 15 to 28, and 29 to 41 doa. Carcass weight, and the absolute and relative (% of carcass weight) weights of carcass parts were determined in 3 birds per treatment-replicate cage at 42 doa. Hatchability of live embryonated injected eggs and hatch residue were not affected by treatment. Across challenge treatment, birds in the 25OHD3 treatment group experienced an increase in BWG between 29 and 41 doa when compared to the D3 or diluent-injected birds. Furthermore, pectoralis major muscle percentage tended (P = 0.059) to increase in birds belonging to the 25OHD3 treatment in comparison to birds in the D3 or diluent-injected treatments. These results indicate that regardless of challenge treatment, 2.4 μg of 25OHD3 may increase the BWG and breast meat yield of birds relative to those that only received an injection of commercial diluent. © 2021 The Authors

The bacterial pathogen Acidovorax citrulli causes the destructive fruit blotch (BFB) on cucurbit plants. Pseudomonas chlororaphis YL-1 is a bacterial strain isolated from Mississippi soil and its genome harbors some antimicrobial-related gene clusters, such as phenazine, pyrrolnitrin, and pyoverdine. Here, we evaluated the antimicrobial activity of strain YL-1 as compared with its deficient mutants of antimicrobial-related genes, which were obtained using a sacB-based site-specific mutagenesis strategy. We found that only phenazine-deficient mutants ∆phzE and ∆phzF almost lost the inhibitory effects against A. citrulli in LB plates compared with the wild-type strain YL-1, and that the main antibacterial compound produced by strain YL-1 in LB medium was phenazine-1-carboxylic acid (PCA) based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Gene expression analyses revealed that PCA enhanced the accumulation of reactive oxygen species (ROS) and increased the activity of catalase (CAT) in A. citrulli. The inhibition effect of PCA against A. citrulli was lowered by adding exogenous CAT. PCA significantly upregulated the transcript level of katB from 6 to 10 h, which encodes CAT that helps to protect the bacteria against oxidative stress. Collectively, the findings of this research suggest PCA is one of the key antimicrobial metabolites of bacterial strain YL-1, a promising biocontrol agent for disease management of BFB of cucurbit plants. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.