AUTHOR=Kolbeck Sandra , Reetz Leonie , Hilgarth Maik , Vogel Rudi F. 

TITLE=Quantitative Oxygen Consumption and Respiratory Activity of Meat Spoiling Bacteria Upon High Oxygen Modified Atmosphere

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02398

DOI=10.3389/fmicb.2019.02398

ISSN=1664-302X

ABSTRACT=<p>High oxygen modified atmosphere packaging is a commonly applied method to prolong the minimum shelf life of fresh (red) meats. Upon spoilage, changes of the initial oxygen concentration and microbiome composition can be observed. Thus, we classified the typical representative meat spoiling bacteria <italic>Brochothrix</italic> (<italic>B.</italic>) <italic>thermosphacta</italic> TMW2.2101 and the four lactic acid bacteria (LAB) <italic>Carnobacterium</italic> (<italic>C.</italic>) <italic>divergens</italic> TMW2.1577, <italic>C. maltaromaticum</italic> TMW2.1581, <italic>Leuconostoc</italic> (<italic>L.</italic>) <italic>gelidum</italic> subsp. <italic>gelidum</italic> TMW2.1618, and <italic>L. gelidum</italic> subsp. <italic>gasicomitatum</italic> TMW2.1619 along their oxygen consuming capacity, which can indicate the timeline of microbiome and sensorial changes. All bacteria were grown in a model system employing gas tight glass bottles containing meat simulation media and under modified atmosphere (70% O<sub>2</sub> and 30% CO<sub>2</sub>). Oxygen concentrations of media and headspaces were monitored over time and the oxygen uptake rate (OUR) was calculated for all species. All bacteria were able to consume dissolved oxygen, with <italic>B. thermosphacta</italic> TMW2.2101 exhibiting a 31-times higher OUR per single cell in 60 h. Furthermore, all strains showed significant growth enhancement in the presence of heme indicating respiratory activity. Comparative genomic and physiological analyses predict the activity of a respiratory chain for all species upon high oxygen atmosphere. An additional cytochrome aa<sub>3</sub> oxidase is suggested to be responsible for the increased OUR of <italic>B. thermosphacta</italic> TMW2.2101. Furthermore, <italic>B. thermosphacta</italic> TMW2.2101 revealed highest oxidative stress tolerance compared to the other bacteria, facilitating a higher respiratory activity. Coupling of respiration and fermentation via regeneration of NADH can be a competitive advantage for meat spoiling bacteria resulting in a higher cell count and possibly accelerated spoilage. The exhibited highest capacity for oxygen consumption of <italic>B. thermosphacta</italic> compared to LAB <italic>in vitro</italic> also suggests a higher contribution of this bacterium to the change in the atmosphere upon spoilage of MAP meats <italic>in situ</italic>.</p>