A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly ...A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly higher(37%-351%)proteolytic activity against peptide substrates(Lys-pNA and Gly-Pro-pNA)at low temperatures(10℃-20℃)and pH 5.0 compared to other L.plantarum strains(YW32,12-3,13-3)isolated from the same source.Inoculation of 7.0 log cfu/mL of L.plantarum NMGL2 with starter culture significantly altered the cheese microbiome during ripening,increasing both diversity and the relative abundance of non-starter lactic acid bacteria(L.plantarum,Lacticaseibacillus paracasei,Leuconostoc mesenteroides,Leuconostoc pseudomesenteroides),while reducing the abundance of Streptococcus thermophilus.This shift in microbial community composition is accompanied by accelerated cheese proteolysis,evidenced by a faster accumulation of short peptides(<1 kDa)and free amino acids in NMGL2-supplemented cheeses over 180 days of ripening.Enhanced proteolysis by NMGL2 resulted in a 1.49-fold increase in total volatile flavour compounds after 180 days,coinciding with the results of the sensory analysis that the odor intensity of Cheddar cheese significantly improved.Furthermore,RDA(redundancy analysis)and PCA(principal component analysis)correlation analysis revealed that the microbial and flavour profiles of 90-day NMGL2-treated cheese closely resembled those of 180-day control cheese.These findings highlight the potential of cold-tolerant L.plantarum NMGL2 as an adjunct culture to accelerate Cheddar cheese ripening.展开更多
Background:Winter climate change including frequent freeze-thaw episodes and shallow snow cover will have major impacts on the spring regrowth of perennial crops.Non-bloating perennial forage legume species including ...Background:Winter climate change including frequent freeze-thaw episodes and shallow snow cover will have major impacts on the spring regrowth of perennial crops.Non-bloating perennial forage legume species including sainfoin,birdsfoot trefoil,red clover,and alsike clover have been bred for their adaptation to harsh winter conditions.In parallel,the selection of cold-tolerant rhizobial strains could allow earlier symbiotic nitrogen(N)fixation to hasten spring regrowth of legumes.Methods:To identify strains forming nodules rapidly and showing high N-fixing potential,60 rhizobial strains in association with four temperate legume species were evaluated over 11 weeks under spring soil temperatures for kinetics of nodule formation,nitrogenase activity,and host yield.Results:Strains differed in their capacity to form efficient nodules on legume hosts over time.Strains showing higher nitrogenase activity were arctic strain N10 with sainfoin and strain L2 with birdsfoot trefoil.For clovers,nitrogenase activity was similar for control and inoculated plants,likely due to formation of effective nodules in controls by endophyte rhizobia present in seeds.Conclusions:Selection based on nodulation kinetics at low temperature,nitrogenase activity,and yield was effective to identify performant rhizobial strains for legume crops.The use of cold-tolerant strains could help mitigate winter climatic changes.展开更多
基金supported by the National Key Research and Development Program of China(2023YFF1103600)the National Center of Technology Innovation for Dairy(No.2022-KYGG-6).
文摘A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly higher(37%-351%)proteolytic activity against peptide substrates(Lys-pNA and Gly-Pro-pNA)at low temperatures(10℃-20℃)and pH 5.0 compared to other L.plantarum strains(YW32,12-3,13-3)isolated from the same source.Inoculation of 7.0 log cfu/mL of L.plantarum NMGL2 with starter culture significantly altered the cheese microbiome during ripening,increasing both diversity and the relative abundance of non-starter lactic acid bacteria(L.plantarum,Lacticaseibacillus paracasei,Leuconostoc mesenteroides,Leuconostoc pseudomesenteroides),while reducing the abundance of Streptococcus thermophilus.This shift in microbial community composition is accompanied by accelerated cheese proteolysis,evidenced by a faster accumulation of short peptides(<1 kDa)and free amino acids in NMGL2-supplemented cheeses over 180 days of ripening.Enhanced proteolysis by NMGL2 resulted in a 1.49-fold increase in total volatile flavour compounds after 180 days,coinciding with the results of the sensory analysis that the odor intensity of Cheddar cheese significantly improved.Furthermore,RDA(redundancy analysis)and PCA(principal component analysis)correlation analysis revealed that the microbial and flavour profiles of 90-day NMGL2-treated cheese closely resembled those of 180-day control cheese.These findings highlight the potential of cold-tolerant L.plantarum NMGL2 as an adjunct culture to accelerate Cheddar cheese ripening.
文摘Background:Winter climate change including frequent freeze-thaw episodes and shallow snow cover will have major impacts on the spring regrowth of perennial crops.Non-bloating perennial forage legume species including sainfoin,birdsfoot trefoil,red clover,and alsike clover have been bred for their adaptation to harsh winter conditions.In parallel,the selection of cold-tolerant rhizobial strains could allow earlier symbiotic nitrogen(N)fixation to hasten spring regrowth of legumes.Methods:To identify strains forming nodules rapidly and showing high N-fixing potential,60 rhizobial strains in association with four temperate legume species were evaluated over 11 weeks under spring soil temperatures for kinetics of nodule formation,nitrogenase activity,and host yield.Results:Strains differed in their capacity to form efficient nodules on legume hosts over time.Strains showing higher nitrogenase activity were arctic strain N10 with sainfoin and strain L2 with birdsfoot trefoil.For clovers,nitrogenase activity was similar for control and inoculated plants,likely due to formation of effective nodules in controls by endophyte rhizobia present in seeds.Conclusions:Selection based on nodulation kinetics at low temperature,nitrogenase activity,and yield was effective to identify performant rhizobial strains for legume crops.The use of cold-tolerant strains could help mitigate winter climatic changes.
