The Influence of a Change in Farm Dairy Practice on the Bacterial Flora of Fresh and Stored Raw Milk

S ummary . The change in farm dairy practice described resulted in an increase in the percentage of pseudomonads isolated from milks stored at 22, 15 and 5° and in the numbers of Gram-negative rod cultures resistant to hypochlorite.     

The Influence of Bacterial Diet on Fat Storage in C. elegans

Background

The nematode Caenorhabditis elegans has emerged as an important model for studies of the regulation of fat storage. C. elegans feed on bacteria, and various strains of E. coli are commonly used in research settings. However, it is not known whether particular bacterial diets affect fat storage and metabolism.

Methodology/Principal Findings

Fat staining of fixed nematodes, as well as biochemical analysis of lipid classes, revealed considerable differences in fat stores in C. elegans growing on four different E. coli strains. Fatty acid composition and carbohydrate levels differ in the E. coli strains examined in these studies, however these nutrient differences did not appear to have a causative effect on fat storage levels in worms. Analysis of C. elegans strains carrying mutations disrupting neuroendocrine and other fat-regulatory pathways demonstrated that the intensity of Nile Red staining of live worms does not correlate well with biochemical methods of fat quantification. Several neuroendocrine pathway mutants and eating defective mutants show higher or lower fat storage levels than wild type, however, these mutants still show differences in fat stores when grown on different bacterial strains. Of all the mutants tested, only pept-1 mutants, which lack a functional intestinal peptide transporter, fail to show differential fat stores. Furthermore, fatty acid analysis of triacylglycerol stores reveals an inverse correlation between total fat stores and the levels of 15-methylpalmitic acid, derived from leucine catabolism.

Conclusions

These studies demonstrate that nutritional cues perceived in the intestine regulate fat storage levels independently of neuroendocrine cues. The involvement of peptide transport and the accumulation of a fatty acid product derived from an amino acid suggest that specific peptides or amino acids may provide nutritional signals regulating fat metabolism and fat storage levels.     

抗生素对新生儿肠道菌群影响的初步研究

本文采用肠道菌群定量定性分析法,利用用药前后的自身对照,研究了静脉应用氨苄青霉素加青霉素的先锋铋对30例足月、患非肠道感染性疾病的新生儿肠道菌群的干扰,结果表明:两组抗生素均造成新生儿肠道菌群紊乱。氨苄青霉素加青霉素使肠杆菌科细菌明显增加,其他细菌无显著变化,优势菌由乳杆菌变为肠杆菌,腹泻率26.7％,菌群失调程度Ⅰ°—Ⅱ°;先锋铋使正常肠菌群成员显著减少,仅酵母菌过盛繁殖,成为优势菌,腹泻率53.3％,菌群失调程度多为Ⅰ°—Ⅱ°。部分Ⅲ°。     

Influence of the Intestinal Flora on the Development of Immune Reactions in Infants

Breast-fed and artifically fed infants are in contact with the O antigen of Escherichia coli from the first days after birth. From the mother, the infant obtains antibodies against nonpathogenic E. coli strains in low titer, and the infant begins to form its own antibodies during the 2nd month of life. The transition is known to be continuous even though the transferred antibodies could not be differentiated from the infant's own antibodies. Contact with endotoxin caused sensitization which was detected by the skin test at about 2.5 months, and thereafter the skin test data correlated with the presence of serum antibodies against endotoxin. The newborn infant can be colonized with a different E. coli serotype; such an antigenic stimulus evokes the formation of antibodies sooner and at a significantly higher titer than (i) the level of maternal antibodies transferred or (ii) the infant's antibodies normally formed later on against other random E. coli serotypes.     

The Effect of the Addition of Copper Sulphate to the Diet on the Bacterial Flora of the Alimentary Tract of the Pig

S ummary : The use of copper sulphate as a dietary supplement had no observable effect on the bacterial content of the alimentary tract of the pig.     

Studies of Intestinal Microflora VII. Effect of Diet and Fecal Microbial Flora on Survival of Animals Exposed to X Irradiation

Changes in the numbers and ratios of bacteria in the feces of rats were produced by administration of three different diets-grain, meat alone, and meat plus lactose. After significant alterations in the intestinal flora had developed, the animals were exposed to a midlethal dose of X irradiation (1,550 R). This treatment led to 100% deaths in rats in which the numbers of coliforms were increased by diet prior to irradiation. Changes in the numbers of lactobacilli appeared to play no role in determining the responses to X-ray exposure. When little or no change was produced by diet and when "normal" microflora was present, the fatality rate was reduced to 60%, and the rate of deaths was retarded when compared with that of the animals in which coliforms were increased.     

彝族健康青年正常肠菌群值的调查

用正常肠菌群检查法,对四川省凉山彝族自治州32例16～25岁彝族健康青年的9类主要正常肠菌群进行调查,各类菌群数均值(Log10~n/克大便)按从多到少的顺位分别是:真杆菌9.47±0.93、乳杆菌8.96±0.6,拟杆菌8.76±1.83、肠杆菌科8.75±0.74、双歧杆菌8.24±0.64、肠球菌8.11±0.83、消化球菌7.84±0.93、葡萄球菌4.2±3.69、酵母菌1.29±1.97。另以9例与彝族青年生活条件相似的汉族青年作对照,结果表明生活条件相似的彝、汉族青年的正常肠菌群值之间无显著性差异。