FORMATION OF SPHEROPLASTS OF MYCOBACTERIUM TUBERCULOSIS BY LYSOZYME

Effects of dietary lysozyme supplementation on growth performance, nutrient digestibility, intestinal microbiota, and blood profiles of weanling pigs challenged with Escherichia coli

The aim of this was evaluate the efficacy of lysozyme on growth performance, nutrient digestibility, excreta microflora population, and blood profiles of weanling pigs under Escherichia coli (E. coli) challenge. A total of 30 piglets weaned at 25 days, 7.46 kg body weight, were assigned to three dietary treatments, composed of five replications, two piglets per replication, for 7 days. The dietary treatment groups were negative control (NC; without antibiotics and lysozyme), positive control (PC; NC + antibiotics), lysozyme (NC + 0.1% lysozyme). All piglets were challenged orally with 6 ml suspension, containing E. coli K88 (2 × 10⁹ CFU/mL). Dietary supplementation with lysozyme and PC resulted in no significant differences in average daily gain and gain to feed efficiency. Weanling pigs fed with E. coli challenge with lysozyme and PC treatments had significantly enhanced nutrient retentions of dry matter and energy (p < 0.05); however, there was a tendency to increase nitrogen digestibility. Furthermore, dietary inclusion of lysozyme and antibiotics treatment groups had a beneficial effect on excreta, ileal, and cecal of the fecal microbial population as decreased E. coli (p < 0.05) counts, without effects on lactobacillus counts. A significant effect were observed on a white blood cells, epinephrine and cortisol concentrations were reduced in piglets fed diets containing E. coli challenge with lysozyme and antibiotics supplementation comparison with the NC group. Therefore, the present data indicate that lysozyme in diet could ameliorate the experimental stress response induced by E. coli in piglets by decreasing intestinal E. coli, white blood cells and stress hormones and improving nutrient digestibility.

Transport of outer membrane lipids in mycobacteria

The complex organization of the mycobacterial cell wall poses unique challenges for the study of its assembly. Although mycobacteria are classified evolutionarily as Gram-positive bacteria, their cell wall architecture more closely resembles that of Gram-negative organisms. They possess not only an inner cytoplasmic membrane, but also a bilayer outer membrane that encloses an aqueous periplasm and includes diverse lipids that are required for the survival and virulence of pathogenic species. Questions surrounding how mycobacterial outer membrane lipids are transported from where they are made in the cytoplasm to where they function at the cell exterior are thus similar, and similarly compelling, to those that have driven the study of Gram-negative outer membrane transport pathways. However, little is understood about these processes in mycobacteria. Here we contextualize these questions by comparing our current knowledge of mycobacteria with better-defined systems in other organisms. Based on this analysis, we propose possible models and highlight continuing challenges to improving our understanding of outer membrane assembly in these medically and environmentally important bacteria. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.

Gene manipulation in mycobacteria

Gene manipulation in mycobacteria developed in two phases. In the first phase genes of mycobacteria were transferred into cells of E. coli and Streptomyces lividans. In the second phase, heterologous genes were transferred into mycobacteria either with a shuttle plasmid or hybrid plasmids. A prerequisite for successful gene manipulation in mycobacteria was a thorough understanding of plasmids in mycobacteria. Construction of recombinant DNA molecules contributed not only to the fact that mycobacteria did not remain outside the mainstream of modern genetic research but also to their present practical importance.

Protoplast formation of selected Mycobacterium smegmatis mutants by lysozyme in combination with methionine

Lysozyme-sensitive mutants of Mycobacterium smegmatis, isolated by nitrosoguanidine treatment, have been converted into protoplasts in a nutritionally enriched medium containing lysozyme and DL-methionine.

Cellular hypersensitivity and cellular immunity in the pathogensis of tuberculosis: specificity, systemic and local nature, and associated macrophage enzymes

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Formation of spheroplasts of Mycobacterium tuberculosis by lysozyme in combination with certain enzymes of rabbit peritoneal monocytes

Spheroplasts of Mycobacterium tuberculosis were formed by culture of the organism in a nutritionally complete medium to which lysozyme and an extract obtained from rabbit peritoneal monocytes were added. The potentiating effect of the factor, or factors, present in the monocyte extract was lost upon prolonged storage at −20 °C or heat at 90 °C for 5 minutes, but was unaffected by dialysis. It was inactive in the presence of fluoride or oxalate. Enzymatic analysis of the monocyte extract showed the presence of lysozyme, acid phosphatase, phospholipase, and trypsin. When acid phosphatase or phospholipase were substituted for the monocyte extract in the lysozyme test system, spheroplast formation was obtained.

Autolysis and secondary growth of Mycobacterium tuberculosis in submerged culture

Mycobacterium tuberculosis has been found to exhibit autolysis and spontaneous secondary growth in modified Sauton medium. The phenomenon is a function of high glycerol concentration of the medium and limitation of air in test tubes. It is not a function of depletion of nutrients and is probably not a manifestation of lysogeny or spheroplast formation. The cycle of growth, autolysis, and secondary growth is related to development of lethal conditions during a period of severe oxygen limitation followed by a metabolic change associated with slower depletion of glycerol.

Spheroplast induction and lysis of BCG strains by glycine and lysozyme

Spheroplast induction and lysis of 6 BCG strains of Mycobacterium tuberculosis by glycine and lysozyme was studied in various media. Spheroplast production was noted in only three strains involving 20% of cell populations. Lysis, as distinct from spheroplast induction, occurred in Dubos medium containing 1.5% glycine and 0.01% lysozyme after 24–48 hours of incubation. Estimation from a standard curve indicated 40 to 70% lysis of the total cell population after 7–10 days of incubation.Similarly, lysis of BCG cells occurred when the inducers, glycine, lysozyme, and lithium chloride, were added to nitrogen-starved cultures grown in Aldridge synthetic medium for 7 to 8 days.

The induction by lysozyme of an L-type growth in Mycobacterium tuberculosis

Lysozyme in combination with ethylenediamine tetraacetic acid (EDTA) gives rise to spheroplasts when Mycobacterium tuberculosis is cultured in a nutritionally complete Tween 80 – albumin medium. These spheroplasts do not multiply in this medium, but when such forms, stabilized by the presence of sucrose and Mg++, are inoculated into PPLO agar or broth an L-form of growth is initiated. A CO2requirement was demonstrated by L-forms grown on solid media.

The production of spheroplasts by rapid-growing non-virulent mycobacteria

Spheroplasts were produced in five strains of rapid-growing non-virulent mycobacteria in a variety of media. Optimal spheroplast production occurred after 8–10 days of incubation in the presence of glycine and lysozyme, but in no culture was there complete formation of spheroplasts. While the pattern of spheroplast induction appeared to be specific for each strain and to be highly reproducible, the mechanism of the induction process is unknown.