Lactobacillus phospholipid molecular species were analyzed by mass spectrometry. Prominent anions were consistent with presence of the phosphatidylglycerols PG(37:2), PG(36:2), PG(35:1), PG(34:1), and PG(33:1). Diglycosyldiacylglycerol molecular species were also observed, although nitrogen-containing phospholipids were absent. An anion of m/z 759 was derived from an apparently novel type of lipid.Numerous studies have investigated the lipid composition of Lactobacillus spp. (8,19,21). Lactobacilli typically have n-C 16:0 , n-C 18:1 , and cyc-C 19 as the major carboxylate constituents, with lesser amounts of n-C 14:0 , n-C 16:1 , and n-C 18:0 and traces of odd-carbon-number acids in some species (6). Such fatty acid profiles are atypical of gram-positive groups but common in gram-positive bacteria (17). Other studies have analyzed polar lipids of lactobacilli and discovered that the vast majority of polar lipid is comprised of phosphatidylglycerol (PG) (8, 11), with smaller amounts of phosphatidic acid, diphosphatidylglycerol (cardiolipin), lysylphosphatidylglycerol (8, 10), phosphoglycolipids (10), and diglycosyldiacylglycerol (DGDG) (18).Virtually nothing is known of the distribution of individual molecular species within each type of phospholipid. In other groups of organisms, such an analysis has required expenditure of considerable time and effort to purify individual molecular species by chromatographic separation and then to analyze each molecular species in turn (2). An alternative approach, recently applied to the study of bacterial phospholipids (1, 3), is fast atom bombardment (FAB) mass spectrometry (MS) in which analysis of mixtures of molecular species is facilitated by the generation of ions retaining the intact molecular structure. FAB MS data for a single strain of Lactobacillus rhamnosus with respect to phospholipid molecular species have been published (7).The aim of this study was to determine the distribution of individual molecular species of phospholipids in a collection of Lactobacillus isolates.Fifteen Lactobacillus strains available from culture collections were analyzed (Table 1). All strains have been described previously (12, 13), and their identities were determined by using the API 50CHL test kit (API System, Vercieu, France) and the IDENTIFY computer program (5). Recent changes in the species assignments of some strains, not covered by the API 50CHL test kit for the identification of L. rhamnosus and L. paracasei subsp. paracasei (4), were incorporated into the computer program. For growth and harvesting, all strains were grown in 200-ml aliquots of MRS broth (Oxoid) for 18 to 24 h at 37ЊC as static batch cultures. Cultures were harvested by centrifugation and washed once in phosphate-buffered saline (pH 7.3). They were then washed in deionized water and freeze-dried. Phospholipid analysis was as follows. The methanol-chloroform extraction procedure, which used mechanical shaking at room temperature, was as described in a previous study (1). Phospholipid molecular species were sep...

Cryptococcal meningitis (CM) is associated with raised intracranial pressure which is linked with serious neurological sequelae. Cryptococcus neoformans produces D-mannitol in vitro and in experimental meningitis in rabbits. Mannitol present in the cerebrospinal fluid (CSF) of CM patients could exacerbate raised intracranial pressure and contribute to neurological damage. To link CSF mannitol to cryptococcal infection, levels of mannitol in the CSF of AIDS patients with CM were measured by gas-liquid chromatography. Mannitol was detected in 19 of 21 samples (range, 1.5 to 26.2 mg/liter), but there was no quantitative correlation between the mannitol concentration and the cryptococcal antigen titer.

The detection of thermonuclease by the Oxford strain and eight clinical isolates of Staphylococcus aureus in a variety of bacteriological broths with and without added blood was examined using a toluidine blue-DNA-agar plate method. In Isosensitest, brain-heart infusion, tryptic soy, nutrient and gas-liquid chromatography broths (all of which do not contain liquoid) thermonuclease detection was uncomplicated. In Bactec broths (containing liquoid) detectable thermonuclease activity was greatly reduced in the absence of blood. The addition of 10% blood to the Bactec broths restored the activity. Liquoid was shown to be responsible for the inhibition of thermonuclease activity, and its effect could be neutralised by the addition of blood, albumin, or haemoglobin. In specimens containing no blood, or insufficient blood to neutralise the liquoid in culture broths, more has to be added to prevent false negative reporting of S aureus. This can be done after growth at the time of thermonuclease testing.Clinical consequences of delayed identification of S aureus in routine blood cultures may be serious. The application of the thermonuclease test to blood culture broths is both fast and specific.

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