How Escherichia coli bacteria develop a particular colonial, 3-D biofilm morphological pattern is still a poorly understood process. Recently, we reported a new E. coli K-12 morphotype exhibited by old macrocolonies d...How Escherichia coli bacteria develop a particular colonial, 3-D biofilm morphological pattern is still a poorly understood process. Recently, we reported a new E. coli K-12 morphotype exhibited by old macrocolonies described as volcano-like. The formative developmental process of this morphotype has been presented as a suitable experimental model for the study of 3D patterning in macrocolony biofilms. Here, we report the optical microscopy observations and genetic analysis that have unveiled the existence of a novel autoaggregative behaviour which generates massive lumpiness over the surface of the volcano-like macrocolonies. These lumpy formations are generated by the autoaggregation and strong interaction of tightly packed bacterial cells in structures with a chondrule-like appearance which give the colony’s surface its characteristic microscopic lumpy phenotype. Furthermore, they exhibit different levels of maturation from the edge to the center of the colony. Hence, its generation appears to follow a spatiotemporal program of development during the macrocolony’s morphogenesis. Interestingly, the agar’s hardness influences the morphology exhibited by these formations, with high agar concentration (1.5%, 15 g/L) suppressing its development. This new auto-aggregative E. coli’s behaviour does not require the activity of the biofilm master regulator CsgD, the adhesiveness of flagella, pili type 1, adhesin Ag43, β-1,6-N-acetyl-D-glucosamine polymer-PGA, cellulose or colanic acid, but it is under glucose repression and the control of cAMP receptor protein (CRP). The possible physiological role of these chondrule-like formations in the adaptability of the colony to different stressful environmental conditions is discussed.展开更多
Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Human-origin <i>Lactobacillus</i> is a preferable source of probiotic bacteria. This stud...Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Human-origin <i>Lactobacillus</i> is a preferable source of probiotic bacteria. This study screened 14 vaginal <i>Lactobacillus</i> strains as probiotic candidates by investigating probiotic-related cell surface characteristics including cell surface hydrophobicity (CSH), Lewis acidity/basicity, autoaggregation, and biofilm formation. Moderate to high CSH and autoaggregation, high basicity and low acidity were prevalent in the 14 tested strains. Biofilm formation varied in a large range among the 14 tested strains. CSH showed a high correlation with Lewis acidity and autoaggregation, while Lewis acidity was highly correlated with autoaggregation and biofilm formation. Four strains were selected as promising probiotic strains. This study was the first one to compare antibiotic sensitivity between biofilm-forming cells and planktonic cells of <i>Lactobacillus</i> species, and found that biofilm-forming cells of a <i>L. fermentum</i> strain had a significantly higher survival rate than planktonic cells in cefotaxime, cefmetazole and tetracycline, but were as sensitive to oxacillin and ampicillin as planktonic cells were.展开更多
通过常规乳酸菌分离技术结合形态观察、生理生化试验,以及16S r DNA同源性分析等方法,从臭豆腐发酵卤水中分离获得7株戊糖片球菌分离株,并通过随机扩增多态性DNA技术构建了不同菌株的特征指纹图谱;以Caco-2细胞和固定化肠黏液蛋白质作...通过常规乳酸菌分离技术结合形态观察、生理生化试验,以及16S r DNA同源性分析等方法,从臭豆腐发酵卤水中分离获得7株戊糖片球菌分离株,并通过随机扩增多态性DNA技术构建了不同菌株的特征指纹图谱;以Caco-2细胞和固定化肠黏液蛋白质作为体外模型,研究了菌株的粘附能力,并探讨了菌株粘附能力与基因型以及表面疏水性、自凝聚能力等表型特征的相关性。结果显示,发酵卤水中的戊糖片球菌存在高度分子多样性,7个分离株中存在6种不同的指纹图谱模式,其中A5型菌株(F28-8和Y27-4)对Caco-2细胞和肠黏液蛋白质的粘附性最强,并显示了高度的疏水性(﹥90%)和较强的自凝聚能力(﹥25%)。相关性分析表明,戊糖片球菌表面疏水率和自凝聚率与Caco-2细胞粘附率测定结果呈显著正相关(r=0.900和0.792,P﹤0.05),但是与肠黏液蛋白质粘附率测定结果相关性不显著(r=0.426和0.700,P﹥0.05)。研究成果为建立高粘附性戊糖片球菌快速筛选方法及其体内定植和分布研究提供了依据。展开更多
文摘How Escherichia coli bacteria develop a particular colonial, 3-D biofilm morphological pattern is still a poorly understood process. Recently, we reported a new E. coli K-12 morphotype exhibited by old macrocolonies described as volcano-like. The formative developmental process of this morphotype has been presented as a suitable experimental model for the study of 3D patterning in macrocolony biofilms. Here, we report the optical microscopy observations and genetic analysis that have unveiled the existence of a novel autoaggregative behaviour which generates massive lumpiness over the surface of the volcano-like macrocolonies. These lumpy formations are generated by the autoaggregation and strong interaction of tightly packed bacterial cells in structures with a chondrule-like appearance which give the colony’s surface its characteristic microscopic lumpy phenotype. Furthermore, they exhibit different levels of maturation from the edge to the center of the colony. Hence, its generation appears to follow a spatiotemporal program of development during the macrocolony’s morphogenesis. Interestingly, the agar’s hardness influences the morphology exhibited by these formations, with high agar concentration (1.5%, 15 g/L) suppressing its development. This new auto-aggregative E. coli’s behaviour does not require the activity of the biofilm master regulator CsgD, the adhesiveness of flagella, pili type 1, adhesin Ag43, β-1,6-N-acetyl-D-glucosamine polymer-PGA, cellulose or colanic acid, but it is under glucose repression and the control of cAMP receptor protein (CRP). The possible physiological role of these chondrule-like formations in the adaptability of the colony to different stressful environmental conditions is discussed.
文摘Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Human-origin <i>Lactobacillus</i> is a preferable source of probiotic bacteria. This study screened 14 vaginal <i>Lactobacillus</i> strains as probiotic candidates by investigating probiotic-related cell surface characteristics including cell surface hydrophobicity (CSH), Lewis acidity/basicity, autoaggregation, and biofilm formation. Moderate to high CSH and autoaggregation, high basicity and low acidity were prevalent in the 14 tested strains. Biofilm formation varied in a large range among the 14 tested strains. CSH showed a high correlation with Lewis acidity and autoaggregation, while Lewis acidity was highly correlated with autoaggregation and biofilm formation. Four strains were selected as promising probiotic strains. This study was the first one to compare antibiotic sensitivity between biofilm-forming cells and planktonic cells of <i>Lactobacillus</i> species, and found that biofilm-forming cells of a <i>L. fermentum</i> strain had a significantly higher survival rate than planktonic cells in cefotaxime, cefmetazole and tetracycline, but were as sensitive to oxacillin and ampicillin as planktonic cells were.
文摘通过常规乳酸菌分离技术结合形态观察、生理生化试验,以及16S r DNA同源性分析等方法,从臭豆腐发酵卤水中分离获得7株戊糖片球菌分离株,并通过随机扩增多态性DNA技术构建了不同菌株的特征指纹图谱;以Caco-2细胞和固定化肠黏液蛋白质作为体外模型,研究了菌株的粘附能力,并探讨了菌株粘附能力与基因型以及表面疏水性、自凝聚能力等表型特征的相关性。结果显示,发酵卤水中的戊糖片球菌存在高度分子多样性,7个分离株中存在6种不同的指纹图谱模式,其中A5型菌株(F28-8和Y27-4)对Caco-2细胞和肠黏液蛋白质的粘附性最强,并显示了高度的疏水性(﹥90%)和较强的自凝聚能力(﹥25%)。相关性分析表明,戊糖片球菌表面疏水率和自凝聚率与Caco-2细胞粘附率测定结果呈显著正相关(r=0.900和0.792,P﹤0.05),但是与肠黏液蛋白质粘附率测定结果相关性不显著(r=0.426和0.700,P﹥0.05)。研究成果为建立高粘附性戊糖片球菌快速筛选方法及其体内定植和分布研究提供了依据。
