Current Microbiology

A soil isolate of Lactobacillus animalis was found to produce a bacteriocin-like inhibitory substance (BLIS) with a wide inhibitory spectrum against Gram-positive bacteria. The isolate exhibited high BLIS production in broth containing surfactants, such as Tween 20 and 80, but low BLIS production in the absence of surfactants. Culture temperature also had an effect on BLIS production. This is the first report to study the production and characteristics of L. animalis BLIS.

Pseudomonas aeruginosa expresses hemolytic phospholipase C (PlcH) with choline or under phosphate-limiting conditions. PlcH from these conditions were differently eluted from the Celite-545 column after application of an ammonium sulfate linear reverse gradient. The PlcH from supernatants of bacteria grown in the presence of choline was eluted with 30% ammonium sulfate and was more than 85% inhibited by tetradecyltrimethylammonium. PlcH from supernatants of bacteria grown with succinate and ammonium ions in a low-phosphate medium was eluted as a peak with 10% of salt and was less than 10% inhibited by tetradecyltrimethylammonium. PlcH from low phosphate was purified associated with a protein of 17 kDa. This complex was dissociated and separated on a Sephacryl S-200 column with 1% (w/v) sodium dodecyl sulfate. After this dissociation, the resulting protein of 70 kDa, corresponding to PlcH, was inhibited by tetradecyltrimethylammonium, showing a protection effect of the accompanying protein. RT-PCR analyses showed that in choline media, the plcH gene was expressed independently of plcR. In low-phosphate medium, the plcH gene was expressed as a plcHR operon. Because plcR encodes for chaperone proteins, this result correlates with the observation that PlcH from supernatants of bacteria grown in the presence of choline was purified without an accompanying protein. The consequence of the absence of this chaperone was that tetradecyltrimethylammonium inhibited the PlcH activity.

In the laboratory, the white rot fungus Phanerochaete chrysosporium degrades numerous organic pollutants. Lack of a slow-release delivery system to toxic waste sites, for this and other fungi, however, constitutes an important barrier to practical implementation. In this study, the use of calcium alginate as an encapsulant for mycelia was investigated; samples were in the form of pellets 1–3 mm in diameter. When refrigerated, alginate-embedded mycelia of P. chrysosporium were viable for one year, both with and without nutrient supplementation. At room temperature, in the absence of nutrient supplementation, viability decreased sharply within 2 months. Addition of sawdust or corncob grits extended the viability of alginate-embedded mycelia; nevertheless, after 9 months only about 20% of the pellets stored at room temperature yielded fungal growth. Spores of P. chrysosporium, embedded in alginate pellets together with corncob grits, gave 75% viability after 9 months of storage at room temperature. Alginate-embedded mycelia were used in Petri plate toxicity tests with 2,4,6-trinitrotoluene (TNT) and gave more rapid and reproducible results than tests performed with mycelial plugs. These experiments demonstrated the feasibility of encapsulating P. chrysosporium in calcium alginate pellets, thus providing a potential method of delivering white rot fungi to toxic waste sites, as well as for developing a system of standardized toxicity testing in plate assays.

Different carbon (C) sources, mainly carbohydrates and lipids, have been screened for their capacity to support growth and lipase production by Penicillium restrictum in submerged fermentation (SmF) and in solid-state fermentation (SSF). Completely different physiological behaviors were observed after the addition of easily (oleic acid and glucose) and complex (olive oil and starch) assimilable C sources to the liquid and solid media. Maximal lipolytic activities (12.1 U/mL and 17.4 U/g) by P. restrictum were obtained with olive oil in SmF and in SSF, respectively. Biomass levels in SmF (12.2–14.1 mg/mL) and SSF (7.0–8.0 mg/g) did not varied greatly with the distinct C sources used. High lipase production (12.3 U/g) using glucose was only attained in SSF, perhaps due to the ability of this fermentation process to minimize catabolite repression.

Sugar uptake was measured with 3H-galactose and 14C-glucose. Galactose transport system was not modified by inhibitors of known translocases and did not present a saturation kinetic with high concentration of galactose. Glucose incorporation was inhibited by lasalocid (cation symport inhibitor) and increased by KCl. The kinetic parameters K M and V max were respectively 9.16 mM and 26.56 nmol/min/mg cell protein. On the basis of this study, galactose crossed through the membrane by diffusion, and glucose was incorporated by a cation symport which is regulated by K+ ions.

A Gram-staining-positive, non-motile, aerobic, spherical actinobacterium, designated WL0053T, was isolated from the coastal sediment of Nantong City, Jiangsu Province, China. The 16S rRNA gene sequence of strain WL0053T exhibited the highest similarities to Nocardioides mesophilus MSL-22T (98.0%), N. massiliensis GD12T (97.8%), Marmoricola bigeumensis MSL-05T (97.6%), and N. jensenii DSM 20641T (97.3%). The polyphasic taxonomic approach was used for the identification of strain WL0053T. This strain formed white, round, and smooth colonies and grew in the presence of 0–18% (w/v) NaCl (optimum, 0–4.0%), at pH 6.0–9.0 (optimum, pH 7.0) and at 20–37 °C (optimum, 28 °C). The main cellular fatty acids comprised of C17:1 ω8c, C18:1 ω9c, and iso-C16:0. The genomic DNA G + C content was 71.9%. The predominant quinone was MK-8(H4), and the major polar lipid consisted of phosphatidylcholine, glycolipid, phosphatidylethanolamine, and two unidentified phospholipids. Phylogenetic trees of 16S rRNA gene and bac120 gene set indicted that strain WL0053T was closely related to the species N. iriomotensis and N. mesophilus, while these two species clustered in a separate clade together with M. caldifontis YIM 730233T in the bac120 tree. Combined with the analysis of average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA–DNA hybridization (dDDH), it can be considered that the strain WL0053T is a new member of the genus Nocardioides and is proposed to be named as Nocardioides jiangsuensis sp. nov.. The type strain is WL0053T (=MCCC 1K05897T=JCM 34671T=GDMCC 4.192T). Furthermore, based on the fact that the genera Nocardioides and Marmoricola both appeared polyphyletic with no significant difference on phenotypic and chemotaxonomic traits, we proposed to reclassify the genus Marmoricola as Nocardioides.

Caulobacter is a well-studied bacterial genus, but little is known about the plasmids that are found in some wild Caulobacter isolates. We used bioinformatic approaches to identify nine plasmids from seven different Caulobacter strains and grouped them based on their size and the similarity of their repABC, parAB, and mobAB genes. Protein pathway analysis of the genes on the K31p1 and K31p2 plasmids showed many metabolic pathways that would enhance the metabolic versatility of the host strain. In contrast, the CB4 plasmid contained 21 heavy metal resistance genes with the majority coding for proteins that enhance copper resistance. Growth assays of C. henricii CB4 demonstrated increased copper resistance and quantitative PCR showed an increase in the expression of eight heavy metal genes when induced with copper.