Growing air pollution,known as"April snow",by fluffy catkins from plant flowering was frequently observed during the Spring time in China.Current efforts mainly focus on controlling catkin release,while thei...Growing air pollution,known as"April snow",by fluffy catkins from plant flowering was frequently observed during the Spring time in China.Current efforts mainly focus on controlling catkin release,while their public health and environmental impacts are unknown.Here,using culturing,microscopic and sequence methods we found that the flying catkins carry a significant amount of bio-agents(bacteria,fungal,viruses,and pollens),e.g.,up to 6.33×10^4 bacterial and 7.46×10^5 fungal cells per catkin.Abundant pollens from plants were also found riding on the flying catkins.For collected fluffy catkins,bacterial Paracoccus,Massilia,fungal Ophiocordyceps,Arthrocladiella,pollen Robina,Pickeringia,Pinus,and viral family Genomoviridae,to name a few,were found to be dominant.With infection and allergic potentials,the detected microbial structures on the fluffy catkins were different from those of local air,varying from one location to another.Being not just white pollution,flying plant fluffy catkins were discovered here also acting as a cloud of biological agents,and further actions need to be taken urgently to understand and limit their environmental and ecological consequences.展开更多
Background:Increasing understanding on the functions of amino acids (AA) has led to new commercial applications and expansion of the worldwide markets.However,the current technologies rely heavily on non-food grade mi...Background:Increasing understanding on the functions of amino acids (AA) has led to new commercial applications and expansion of the worldwide markets.However,the current technologies rely heavily on non-food grade microorganism and chemical synthesis for the production of AA.Several studies reported that lactic acid bacteria (LAB) have the capability of producing AA owing to their well-established proteolytic system and amino acid biosynthesis genes.Hence,the objectives of this study were to explore the extracellular proteolytic activity of LAB isolated from various Malaysian fermented foods and their potential to produce AA extracellularly as feed supplements.Results:All the studied LAB isolates were versatile extracellular protease producers,whereby extracellular protease activities were detected from acidic to alkaline pH (pH 5,pH 6.5,pH 8) using qualitative and quantitative proteolytic assays.The highest proteolytic activity at pH 5 (15.76 U/mg) and pH 8 (19.42 U/mg) was achieved by Lactobacillus plantarum RG14,while Lactobacillus plantarum RS5 exhibited the highest proteolytic activity of 17.22 U/mg at pH 6.5.As for the results of AA production conducted in de Man,Rogosa and Sharpe medium and analysed by high pressure liquid chromatography system,all LAB isolates were capable of producing an array of AA.Generally,Pediococcus sp.showed greater ability for AA production as compared to Lactobacillus sp.Moreover,the studied LAB were able to produce a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.P.pentosaceus TL-3 recorded the highest methionine and threonine productivity of 3.72 mg/L/h and 5.58 mg/L/h respectively.However,L.plantarum I-UL4 demonstrated a lysine productivity of 1.24 mg/L/h,while P.acidilactici TP-6 achieved up to 1.73 mg/L/h of tryptophan productivity.Conclusion:All the 17 studied LAB isolates possessed versatile extracellular proteolytic system and have vast capability of producing various amino acids including a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.Despite AA production was strain dependent,the studied LAB isolates possessed vast potential and can be exploited further as a bio-agent or an alternative amino acids and bioactive peptide producers.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.21725701 and 22040101)。
文摘Growing air pollution,known as"April snow",by fluffy catkins from plant flowering was frequently observed during the Spring time in China.Current efforts mainly focus on controlling catkin release,while their public health and environmental impacts are unknown.Here,using culturing,microscopic and sequence methods we found that the flying catkins carry a significant amount of bio-agents(bacteria,fungal,viruses,and pollens),e.g.,up to 6.33×10^4 bacterial and 7.46×10^5 fungal cells per catkin.Abundant pollens from plants were also found riding on the flying catkins.For collected fluffy catkins,bacterial Paracoccus,Massilia,fungal Ophiocordyceps,Arthrocladiella,pollen Robina,Pickeringia,Pinus,and viral family Genomoviridae,to name a few,were found to be dominant.With infection and allergic potentials,the detected microbial structures on the fluffy catkins were different from those of local air,varying from one location to another.Being not just white pollution,flying plant fluffy catkins were discovered here also acting as a cloud of biological agents,and further actions need to be taken urgently to understand and limit their environmental and ecological consequences.
基金The Long-Term Research Grant(LRGS)of the Ministry of Education of Malaysia supported this work
文摘Background:Increasing understanding on the functions of amino acids (AA) has led to new commercial applications and expansion of the worldwide markets.However,the current technologies rely heavily on non-food grade microorganism and chemical synthesis for the production of AA.Several studies reported that lactic acid bacteria (LAB) have the capability of producing AA owing to their well-established proteolytic system and amino acid biosynthesis genes.Hence,the objectives of this study were to explore the extracellular proteolytic activity of LAB isolated from various Malaysian fermented foods and their potential to produce AA extracellularly as feed supplements.Results:All the studied LAB isolates were versatile extracellular protease producers,whereby extracellular protease activities were detected from acidic to alkaline pH (pH 5,pH 6.5,pH 8) using qualitative and quantitative proteolytic assays.The highest proteolytic activity at pH 5 (15.76 U/mg) and pH 8 (19.42 U/mg) was achieved by Lactobacillus plantarum RG14,while Lactobacillus plantarum RS5 exhibited the highest proteolytic activity of 17.22 U/mg at pH 6.5.As for the results of AA production conducted in de Man,Rogosa and Sharpe medium and analysed by high pressure liquid chromatography system,all LAB isolates were capable of producing an array of AA.Generally,Pediococcus sp.showed greater ability for AA production as compared to Lactobacillus sp.Moreover,the studied LAB were able to produce a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.P.pentosaceus TL-3 recorded the highest methionine and threonine productivity of 3.72 mg/L/h and 5.58 mg/L/h respectively.However,L.plantarum I-UL4 demonstrated a lysine productivity of 1.24 mg/L/h,while P.acidilactici TP-6 achieved up to 1.73 mg/L/h of tryptophan productivity.Conclusion:All the 17 studied LAB isolates possessed versatile extracellular proteolytic system and have vast capability of producing various amino acids including a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.Despite AA production was strain dependent,the studied LAB isolates possessed vast potential and can be exploited further as a bio-agent or an alternative amino acids and bioactive peptide producers.
