Amino acids of the cell wall of Nocardia rubra

Endogenous ocular nocardiosis: a clinical and experimental study

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Characterization of Nocardia amarae as a Potent Biological Coalescing Agent of Water-Oil Emulsions

Nocardia amarae grown in a liquid medium induced coalescence of emulsions which differed in type, composition of the organic phase, and structure of stabilizing emulsifiers. De-emulsifying activity varied with the type of growth medium, culture age, and postharvest treatment. Based on extraction and degradation studies, it was concluded that de-emulsifying properties are due to the bacterial cell surface. Thus, bacteria may provide a new source of de-emulsifying agents.

Cell wall modification resulting from in vitro induction of L-phase variants of Nocardia asteroides

The chemical composition of the cell walls of several L-form revertants derived from Nocardia asteroides 10905 was determined at different stages of growth. It was observed that each L-form revertant had a cell well that differed from that of the parental strain when grown under identical conditions. In some strains the peptidolipid and mycolic acid components were affected the most, whereas in other strains the fatty acid, sugar, and mycolic acid moieties were altered. Shifts in mycolic acid size were prominent, whereas the basic peptidoglycan structure appeared to be affected the least. Both the method used to induce the L-form of N. asteroides 10905 and the length of time these organisms were maintained in the wall-less state affected the degree of cell wall modification during the reversion process. Thus, removal of the cell wall appeared to potentiate and select for mutational alterations within the cell envelope of N. asteroides, and these changes resulted in altered cellular and colonial morphology.

Mycobacterium

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In vitro spheroplast and L-form induction within the pathogenic nocardiae

Six strains of Nocardia asteroides, two strains of N. caviae, and two strains of N. braziliensis were grown in medium supplementted with glycine, lysozyme, D-cycloserine, glycine plus lysozyme, and glycine plus D-cycloserine. It was shown that three strains of N. asteroides, and two strains of N. caviae, readily formed spheroplasts and/or protoplasts when grown in the presence of glycine plus either lysozyme or D-cycloserine. This process was studied by both phase contrast microscopy and electron microscopy. The induced cultures were then plated on hypertonic medium for the isolation of L-forms. It was shown that the organisms differed greatly in their ability to produce spheroplasts and subsequently grew as L-forms or transitional-phase variants.

Structural and biochemical alterations of Nocardia asteroides cell walls during its growth cycle

Analysis of Nocardia asteroides 14759 cell walls were done to determine the chemical and structural composition during the growth cycle. It was found that the ultrastructural profiles of the cell wall become altered as the cultures aged. Chemical analysis revealed corresponding shifts in cell wall components as the culture went from lag to logarithmic to stationary phases of growth. The peptidoglycan from lag-phase cells (5 h) represented 15% of the total cell wall weight, and the percentage of peptidoglycan progressively increased so that, in 1-week stationary-phase cells, it represented approximately 40% of the total wall weight. In lag-phase cells it was found that 36% of the cell wall weight was lipid in nature, whereas stationary-phase cells had only 7% lipid in their wall. The overall sugar composition of the walls remained relatively constant at about 28 to 31% however, the arabinose to galactose ratio changed from approximately 1:1 in lag-phase to 2:1 in stationary-phase cells. Gas-liquid chromatography demonstrated that the fatty acids making up the cell wall lipids changed relative to one another as the cells aged. Based upon the removal of lipids by ethanol-ether, chloroform, and alkaline methanol extraction, it was shown that the classes of loosely and firmly associated lipids changed as the cells aged. Further, it was found that a carotenoid-like pigment associated to a C22 fatty acid increased in the cell wall as the culture stopped growing. Peptidolipid or lipoprotein was found to make up a significant part of the cell wall. This component increased in amount and varied in amino acid content as the culture aged. Analysis of the totally extracted basal layer of the cell wall (peptidoglycan plus arabinogalactan) showed that it too changed as the cells grew and fragmented. The data presented established that the cell wall of N. asteroides was structurally and chemically complex and that a progression of chemical and physical processes occurred within the wall as the cells developed through their growth cycle.

Probable L-forms of Nocardia asteroides induced in cultured mouse peritoneal macrophages

Mouse peritoneal macrophages were infected with varying numbers of Nocardia asteroides 10905, and the fate of the ingested organisms was determined by viable plate count (VPC), light microscopy (LM), immunofluorescent microscopy (IM), and electron microscopy (EM). The results obtained with these methods differed. VPC indicated that intracellular Nocardia decreased in numbers during the first 12 days, followed by significant increases after 16 days. LM suggested that N. asteroides 10905 was slowly degraded by macrophages with no subsequent increases observed. In contrast, IM demonstrated large numbers of intracellular Nocardia throughout the experiment. EM studies of infected macrophages failed to demonstrate intact bacteria after 8 days; however, wall-less and spheroplast-like organisms were seen. These results suggested that N. asteroides 10905 was present within the macrophages in an altered form. By using hypertonic culture medium, we were able to isolate, from infected macrophages, organisms which exhibited many of the properties of bacterial L-forms. IM demonstrated these variants to be of nocardial origin. These altered forms also reverted to typical nocardial cells either spontaneously or upon transfer into broth. These findings indicate that N. asteroides 10905 is capable of existing within macrophages in an altered state. Further investigation is in progress to determine whether these altered forms represent L-forms or transitional-phase variants.

Chemical characterization of organisms isolated from leprosy patients

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

An ultrastructural analysis of Nocardia during experimental infections in mice

Several strains of Nocardia that varied from virulent to avirulent were injected intraperitoneally into young mice. Histological and ultrastructural analysis of the resultant infections revealed that the bacteria and the lesions they induced were different depending upon the strain of organism used. Further, the morphological and tinctorial characteristics of the bacteria grown in vitro changes during growth in vivo. These observations strongly suggested that chemical and physical alterations occurred in the cell envelope of the Nocardia when grown in mice. Electron microscopy confirmed that significant structural modification occurred, especially in the cell envelope, when the nocardial cells established themselves within the host tissue. It was shown that the least virulent strain exhibited the most dramatic changes whereas the most virulent organism appeared to be affected the least.

Cytochemical reactions of human leprosy bacilli and mycobacteria: ultrastructural implications

Leprosy bacilli harvested from freshly biopsied tissue from cases of lepromatous, borderline and histoid leprosy were, in conjunction with Mycobacterium lepraemurium and representative mycobacteria, examined cytochemically with and without their pyridine-extractable acid-fastness. Unlike the mycobacteria, unextracted leprosy bacilli failed to give a positive response to the periodic acid Schiff test or to take up Sudan black B, toluidine blue O, alkaline methylene blue or safranin O. Once their acid-fastness was removed with pyridine, leprosy bacilli were stained by all of the foregoing dyes except Sudan black B, under this condition they remained gram positive. While permanent loss of acid-fastness from leprosy bacilli always resulted in a loss of acid hematein-fixing material (Smith-Dietrich-Baker tests), the reverse was not true. Mild aqueous saponification, bromination, or sequential treatment with lipase and phospholipase D resulted in a loss of acid hematein-positivity but not acid-fastness. After pyridine extraction, bromination, or aqueous saponification, true mycobacteria lost neither their acid hematein-positivity nor their acid-fastness. The acid hematein-positive material and the acid-fastness of both leprosy bacilli and mycobacteria were lost after treatment with alkaline ethanol. These cytochemical findings are discussed in the light of what is known of the ultrastructure of leprosy bacilli and mycobacteria, and of the occurrence of a dl-3, 4-dihydroxyphenylalanine oxidase in leprosy bacilli but not in mycobacteria. An effort is made to explain the rather unique cytochemical properties of leprosy bacilli. Since pyridine-extractable acid-fastness (and acid hematein-positivity) serve to distinguish human leprosy bacilli from M. lepraemurium, one or the other, or both, are suggested as bases for differentiating these two organisms in animal experiments designed to show the in vivo propagation of human leprosy bacilli.