Project description:Oxygen and carbon dioxide are common protective gases used in modified atmosphere packaging (MAP) of meat. Within the package, they selectively suppress members of the spoilage microbiome, reshaping it to adapted species concomitantly growing upon MAP. Thus, this species must exhibit adaptation mechanisms to withstand the inhibitory effect of carbon dioxide and oxygen, and cope with selective nutrition on MAP meat. In order to uncover these mechanisms, the typical representative meat-spoiling bacteria Brochothrix (B.) thermosphacta TMW2.2101 and four lactic acid bacteria (LAB) Carnobacterium (C.) divergens TMW2.1577, C. maltaromaticum TMW2.1581, Leuconostoc (L.) gelidum subsp. gelidum TMW2.1618 and L. gelidum subsp. gasicomitatum TMW2.1619 were grown in a meat simulation medium under a controlled, sterile environment, aerated constantly with either air, 100%_N2, 30%_CO2/70%_O2 or 30%_CO2/70%_N2. Growth dynamics were monitored and a label-free quantitative mass spectrometric approach was employed to determine changes within the bacterial proteomes in response to the different gas atmospheres. Revealed bacterial tolerance to modified atmospheres (MA) comprise two possible scenarios: Either bacteria were intrinsically adapted to MA, exhibiting no proteomic regulation of enzymes (L. gelidum subsp. gelidum and gasicomitatum) or, tolerance was provided by varying specific metabolic adaptation (B. thermosphacta, C. divergens, C. maltaromaticum). In detail, metabolic adaptation mechanisms to oxygen comprised an enhanced oxidative stress reduction response, adjustment of the pyruvate metabolism and catabolic oxygen consuming reactions. Adaptation to carbon dioxide was characterized by an upregulation of proteins involved in intracellular pH homeostasis, maintenance of osmotic balance and alteration of the fatty acid composition of the cell membrane. We furthermore predict species-specific strategies for different and preferential carbon source utilization enabling a non-competitive coexistence on meat and resulting in a synergistic spoilage. We conclude that a gas atmosphere containing 30%_CO2/70%_O2 has no inhibitory effect on the analyzed prominent meat-spoiling bacteria whereas 30%_CO2/70%_N2 predictively inhibits C. divergens TMW21577 and B. thermosphacta TMW2.2101 but not the other three species. This gives a mechanistically explanation of their acknowledged status as typical spoilage organisms on packaged meats.
Project description:Western commercial pig breeds have been intensively selected, resulting in a sizeable, rapid, and efficient accretion of muscle but a reduction in meat quality. When compared with Western commercial pig breeds, Chinese indigenous pig breeds exhibited slower growth rates and reduced lean meat content but superior perceived meat quality. To study the factors that determine meat quality, we examined piglets of one Western commercial breed (Yorkshire) and one Chinese indigenous breed (Wannanhua) and sequenced the longissimus dorsi muscle using RNA-sequencing (RNA-seq). We analyzed their transcriptomes, focusing on identifying candidate genes that may influence porcine muscle growth, meat quality and adipose deposition. Gene ontology functional enrichment and pathway enrichment analyses identified differentially expressed genes primarily associated with glycolytic metabolism, biological processes of muscle development and signaling pathways related to fatty acid metabolism, growth and carcass traits. This finding suggests that the differentially expressed genes may play important roles in determining meat quality traits. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmed the differential expression of twelve selected differentially expressed genes. This study identified a number of novel candidate genes for porcine meat quality and carcass traits that merit further investigation to elucidate the molecular mechanisms responsible for muscle growth and fat deposition.
Project description:This study applied peptidomics to investigate potential biomarkers for evaluating pork-meat freshness. Meat samples stored at -2, 4, 10, and 25 °C were collected at specific time points to evaluate meat freshness indicators (color, total viable count, pH, and total volatile basic nitrogen). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profile was analyzed, and substantial protein degradation (myosin heavy chain, paramyosin, troponin) was detected at the end of storage, regardless of the temperature. Peptidomics analysis was performed using a UHPLC-LTQ-Orbitrap mass spectrometer, and the potential peptide marker MVHMASKE was filtered via multivariate analysis and quantified by parallel reaction monitoring combined with external standard quantitation. In addition, the relationship between peptide content and change in meat freshness was verified using real-life samples and the content of MVHMASKE showed an obvious decline during storage, presenting a period of pork meat from fresh to spoilage. This study provides favorable evidences to evaluate pork meat freshness by mass spectrometry-based pep-tidomics.
Project description:Granny Smith apples (Malus x domestica Borkh) grown in commercial orchards were harvested at physiological mature stage and maintained 6 months in cold storage with or without 1-MCP post-harvest treatment, and with or without enriched ozone atmosphere.
2020-03-09 | GSE133456 | GEO
Project description:meat spoilage bacteria Genome sequencing and assembly
| PRJNA336488 | ENA
Project description:Spoilage microbiota in retail packaged broiler meat