Biology subjects

Finnegan, P.

Publications and source records attributed to Finnegan, P..

3 recordsLinked to original sources

bioRxiv2025

Variations in cow milk and teat skin microbiota across the lactation cycle with intra-mammary cephalosporin use at dry-off

Cephalosporins and other broad-spectrum antibiotics are frequently administered prophylactically into the udder when dairy cows end their lactation cycle, termed dry-off, to reduce mastitis risk. However, the use of antibiotics on cows that do not have signs of infection may result in the selection of microbes resistant to antibiotics and negatively alter the udder microbiome composition. In this study, the effects of intramammary cephalosporin therapy with either Cephapirin (CB) or Ceftiofur (CH) on milk and teat skin microbiota were examined for three dairies in California. Bacterial composition was measured for cows with low somatic cell counts (SCC,<100,000 cells /mL) and high, subclinical SCC (>200,000 cells/mL). Samples were collected at dry-off (before treatment), seven days later, and 55-75 Days in Milk (DIM) in the next lactation cycle. The milk and skin microbiota were largely separated based on dairy (milk: R2 = 6.22, skin: R2 = 7.56) and day of sampling (milk: R2 = 4.74 and skin: R2 = 3.77). CB or CH use was associated with a small but significant impact on the milk microbiota beta-diversity (Bray-Curtis, p =0.003, R2= 1.4%) but no effect was observed on the skin. At one dairy (Dairy 3), milk from cows receiving CB and CH had a reduction in proportions of Staphylococcaceae at 55-75DIM compared to untreated cows. Overall, antibiotic use did not result in large significant changes to bacterial diversity in milk or on the teat skin, and instead the microbiota at those sites mainly differed between the time and location of sampling. ImportanceThe use of antibiotics in agriculture is under increasing scrutiny due to the rising spread of antimicrobial resistant bacteria. Our study showed that common preventative antibiotic intramammary treatment of cows with cephalosporins at the end their lactation (dry-off) had minimal effects on the milk and teat skin microbiota on asymptomatic cows with high somatic cell counts.

microbiology↗

bioRxiv2021

Balancing growth amidst salinity stress-lifestyle perspectives from the extremophyte model Schrenkiella parvula

Schrenkiella parvula, a leading extremophyte model in Brassicaceae, can grow and complete its life cycle under multiple environmental stresses, including high salinity. While foundational genomic resources have been created for S. parvula, a comprehensive physiological or structural characterization of its salt stress responses is absent. We aimed to identify the influential traits that lead to stress-resilient growth of this species. We examined salt-induced changes in the physiology and anatomy of S. parvula throughout its lifecycle across multiple tissues. We found that S. parvula maintains or even exhibits enhanced growth during various developmental stages at salt stress levels known to inhibit growth in Arabidopsis and most crops. The resilient growth of S. parvula was associated with key traits that synergistically allow continued primary root growth, expansion of xylem vessels across the root-shoot continuum, and a high capacity to maintain tissue water levels by developing larger and thicker leaves while facilitating continued photosynthesis during salt stress. These traits at the vegetative phase were followed by a successful transition to the reproductive phase via early flowering, development of larger siliques, and production of viable seeds during salt stress. Additionally, the success of self-fertilization during early flowering stages was dependent on salt-induced filament elongation in flowers that aborted in the absence of salt. Our results suggest that the maintenance of leaf water status and enhancement of selfing in early flowers to ensure reproductive success, are among the most influential traits that contribute to the extremophyte lifestyle of S. parvula in its natural habitat. One sentence summarySchrenkiella parvula salt-resilient growth is facilitated by uncompromised primary root growth, expansion of xylem vessels, maintenance of leaf water status and photosynthesis, and early flowering.

plant biology↗

bioRxiv2021

Extracellular electron transfer increases fermentation in lactic acid bacteria via a hybrid metabolism

Energy conservation in microorganisms is classically categorized into respiration and fermentation, however recent work shows some species can use mixed or alternative bioenergetic strategies. We explored the utility of a flavin-based extracellular electron transport (FLEET) system for energy conservation within diverse lactic acid bacteria (LAB), microorganisms that mainly rely on fermentative metabolism and are important in food fermentations. The LAB Lactiplantibacillus plantarum uses extracellular electron transfer to increase its NAD+/NADH ratio, generate more ATP through substrate-level phosphorylation and accumulate biomass more rapidly. This novel, hybrid metabolism was dependent on a type-II NADH dehydrogenase (Ndh2) and conditionally required a flavin-binding extracellular lipoprotein (PplA) in the FLEET system to confer increased fermentation yield, metabolic flux, and environmental acidification in both laboratory media and food fermentation. The discovery of a single pathway that blends features of fermentation and respiration expands our knowledge of energy conservation metabolism and provides immediate biotechnology applications.

microbiology↗