Current Microbiology

Kalinovskaya, Nataliya; Dmitrenok, Andrey; Kuznetsova, Tatyana; Frolova, Galina; Christen, Richard; Laatsch, Hartmut; Alexeeva, Yulia; Ivanova, Elena

doi: 10.1007/s00284-007-9023-6pmid: 18180994

The marine bacterium “Pseudoalteromonas januaria” SUT 11 isolated from a seawater sample produced the rare cell-bound cyclic lipodepsipeptides A/A′, B/B′, and C/C′. The matrix-assisted laser desorption/ionization mass spectra indicated that one bromine atom presented in the peptides B/B′ and C/C′, whereas the component A/A′ contained no bromine atom. The acyldepsipeptides A/A′–C/C′ have an identical amino acid sequence, Thr-Val-Asn-Asn-Leu/allo-Ile, but differed in C-terminal amino acid and acyl moieties. Peptides A–C have Leu as a C-terminal amino acid, whereas peptides A′-C′ have allo-Ile. Acyl moieties in peptides A/A′, B/B′, and C/C′ have been found to consist of 11-(4′-hydroxyphenyl)-undeca-2,4,6,8,10-pentaenic acid, 9-(3′-bromo-4′-hydroxyphenyl)-nona-2,4,6,8-tetraenic acid, and 11-(3′-bromo-4′-hydroxyphenyl)-undeca-2,4,6,8,10-pentaenic acid, respectively. The structure of a main pair of peptides B/B′ with molecular masses 843/845 Da has been determined by means of ultraviolet, infrared, and two-dimensional nuclear magnetic resonance spectroscopy. We have demonstrated that tandem nano-electrospray ionization mass spectrometry is a very efficient way for the fast and sensitive investigation of lipopeptides A/A′ and C/C′ with molecular masses 791 and 869/871 Da, respectively, which have been isolated in small amounts.

Ding, Ling; Qin, Song; Li, Fuchao; Chi, Xiaoyuan; Laatsch, Hartmut

doi: 10.1007/s00284-007-9063-ypmid: 18214603

Cladosporium sp. isolate N5 was isolated as a dominant fungus from the healthy conchocelis of Porphyra yezoensis. In the re-infection test, it did not cause any pathogenic symptoms in the alga. Twenty-one cultural conditions were chosen to test its antimicrobial activity in order to obtain the best condition for large-scale fermentation. Phenylacetic acid, p-hydroxyphenylethyl alcohol, and l-ß-phenyllactic acid were isolated from the crude extract as strong antimicrobial compounds and they are the first reported secondary metabolites for the genus Cladosporium. In addition, the Cladosporium sp. produced the reported Porphyra yezoensis growth regulators phenylacetic acid and p-hydroxyphenylacetic acid. No cytotoxicity was found in the brine shrimp lethality test, which indicated that the environmental-friendly Cladosporium sp. could be used as a potential biocontrol agent to protect the alga from pathogens.

Zhang, Yan; Zhang, Huiwen; Li, Xinyu; Su, Zhencheng; Zhang, Chenggang

doi: 10.1007/s00284-007-9064-xpmid: 18176824

Cadmium-resistant bacteria were isolated from the farmland soil in Zhangshi Irrigation Area in Shenyang of Northeast China, an area has been polluted by heavy metals, especially cadmium, for more than 40 years. The cadA gene was detected in 4 Bacillus strains and for the first time in one Flavobacterium strain. The high sequence identity (93%–99%) of cadA gene, shared indels in different bacterial species and genera, and the phylogenetic incongruence between 16S rDNA gene tree and cadA gene tree suggested that lateral gene transfer (LGT) occurred among Bacillus and Flavobacterium spp. The LGT of cadA gene might play a vital role in promoting the spread of cadmium-resistant phenotypes throughout soil microbial communities.

Yu, Mengyao; Ma, Bo; Luo, Xia; Zheng, Linyong; Xu, Xiaoyan; Yang, Zhirong

doi: 10.1007/s00284-007-9067-7pmid: 18180993

Due to unsatisfying attempts to fingerprint Auricularia polytricha, two different molecular maker systems—Inter-Simple Sequence Repeats (ISSR) and Sequence-related amplified polymorphism (SRAP)—were established and tested to quantify molecular diversity among 19 strains of this fungus. A total of 202 (99.0%) and 459 (95.9%) polymorphic bands were detected by 13 ISSR primers and 14 SRAP primer combinations, respectively. By parsimony method, a phylogenetic tree was constructed based on each analysis; the two trees show that 19 A. polytricha strains were distributed into five or four groups. These results demonstrated that both methods were suitable for discriminating among strains of A. polytricha, and the novel SRAP markers are more efficient and preferable. The result also indicated the high level of genetic diversity of A. polytricha and their relationship between each other. These findings would benefit future research in A. polytricha, especially in breeding and medicine development. It also gives a useful method for fingerprinting of other fungi.

Doshi, Hiren; Seth, Chetan; Ray, Arabinda; Kothari, I.

doi: 10.1007/s00284-007-9070-zpmid: 18167026

The biosorption of metal ions (Cr+3, $$ {\text{Cr}}_{{\text{2}}} {\text{O}}^{{ - 2}}_{7} $$ , Cu+2, and Ni+2) on two algal blooms (designated HD-103 and HD-104) collected locally was investigated as a function of the initial metal ion concentration. The main constituent of HD-103 is Cladophora sp., while Spirulina sp. is present significantly in the bloom HD-104. Algal biomass HD-103 exhibited the highest Cu+2 uptake capacity (819 mg/g). This bloom adsorbed Ni+2 (504 mg/g), Cr+3 (347 mg/g), and $$ {\text{Cr}}_{{\text{2}}} {\text{O}}^{{ - 2}}_{7} $$ (168 mg/g). Maximum of Ni+2 (1108 mg/g) is taken by HD-104. This species takes up 306, 202, and 576 mg/g Cr+3, $$ {\text{Cr}}_{{\text{2}}} {\text{O}}^{{ - 2}}_{7} $$ , and Cu+2, respectively. Equilibrium data fit very well to both the Langmuir and the Freundlich isotherm models. The sorption process followed the Freundlich model better. Pseudo-first-order kinetic model could describe the kinetic data. Infrared (IR) spectroscopic data were employed to identify the site(s) of bonding. It was found that phosphate and peptide moieties participate in the metal uptake by bloom HD-103. In the case of bloom HD-104, carboxylate and phosphate are responsible for the metal uptake. The role of protein in metal uptake by HD-103 was investigated using polyacrylamide gel electrophoresis.

Hatch, Jennifer; Finneran, Kevin

doi: 10.1007/s00284-007-9073-9pmid: 18167025

Several reports suggest that extracellular electron shuttles influence fermentative metabolism in a beneficial manner for bioremediation and biotechnology strategies. The focus of this research was to characterize the effects of reduced electron shuttling molecules on fermentative H2 production. Reduced electron shuttles may provide reducing equivalents to generate H2, which influences alternate cellular processes. Electron shuttling compounds cycle between reduced-oxidized states and influence fermentative physiology. Clostridium beijerinckii fermentation was altered using a physiological approach that resulted in H2 production with the reduced extracellular electron shuttle anthrahydroquinone-2,6,-disulfonate (AH2QDS) and biologically reduced humic substances as the primary electron donors. Cells were suspended in a buffer with an excess of the biological electron transfer molecule NAD+, with AH2QDS (100–1000 μM) or biologically reduced humic substances (0.01–0.025 g/L) as the sole electron source. Increasing concentrations of AH2QDS and reduced humics increased H2 production, while H2 production was suppressed by Fe(III) hydroxides, which outcompeted the cells for electrons from the reduced shuttles, suggesting that the shuttles are in fact electron donors for H2 production. Oxidized AQDS/humics did not increase H2 production. Organic acid production shifted toward butyric acid in the presence of reduced electron shuttles, particularly with growing cells. Growth and hydrogen production rates in growing cells were initially faster in the presence of the reduced electron shuttles; however, the final biomass yield was inversely proportional to the starting AH2QDS concentration, which suggests that reduced shuttles may compete with anabolic cell processes for available energetic resources or that the shift to excess butyrate becomes toxic to the cells.

Halling, Shirley; Jensen, Allen; Olsen, Steven

doi: 10.1007/s00284-007-9074-8pmid: 18214602

Intracellular pathogens selected for increased susceptibility to polycations are commonly attenuated, yet the effect of decreased susceptibility to polycations on pathogenicity has not been researched. The polymyxin-resistant mutant Brucella abortus AJ100 was characterized by comparing its susceptibility to the polycationic antibiotic polymyxin B, defensins, and lactoferricin, and its colonization and clearance in the mouse model to the parent strain RB51. MIC (minimum inhibitory concentration) values determined by Etest for AJ100 and RB51 were 1.5 and 0.25 μg/ml, respectively. Though AJ100 is less susceptible to polymyxin B than RB51, it was more susceptible than its parent strain to the cationic defensins melittin, magainin 2, and cecropin P1. In the mouse model, initial colonization of the spleen was lower for AJ100 than RB51, and the rate of clearance from the spleen was faster for AJ100 than RB51. However, initial colonization and clearance rates of AJ100 from the liver were indistinguishable from those of RB51. This study suggests that the susceptibility profile of Brucella to polycationic defensins rather than polymyxin B may be indicative of differential survival in the spleen and liver in the mouse and is indicative of spleen and liver residential macrophages’ differing ability to inactivate Brucella.

Godlewska, Renata; Pawlowski, Marcin; Dzwonek, Artur; Mikula, Michal; Ostrowski, Jerzy; Drela, Nadzieja; Jagusztyn-Krynicka, Elżbieta

doi: 10.1007/s00284-007-9083-7pmid: 18172719

A product of the Helicobacter pylori hp0596 gene (Tip-α) is a highly immunogenic homodimeric protein, unique for this bacterium. Cell fractionation experiments indicate that Tip-α is anchored to the inner membrane. In contrast, the three-dimensional model of the protein suggests that Tip-α is soluble or, at least, largely exposed to the solvent. hp0596 gene knockout resulted in a significant decrease in the level of H. pylori colonization as measured by real-time PCR assay. In addition, the Tip-α recombinant protein was determined to stimulate macrophage to produce IL-1α and TNF-α. Both results imply that Tip-α is rather loosely connected to the inner membrane and potentially released during infection.

Fu, Ling-lin; Xu, Zi-rong; Shuai, Jiang-bing; Hu, Chun-xia; Dai, Wei; Li, Wei-fen

doi: 10.1007/s00284-007-9077-5pmid: 18172721

A chimeric gene mHG (669 bp) was constructed by substitution of Clostridium thermocellum ZJL4 lichenase (CG) N-terminal fragment (except its signal sequence) for the counterpart of Bacillus sp. A3 lichenase (BG). To acquire high-level secretion of the chimeric lichenase (mHG) in Bacillus subtilis, a series of site-mutated signal peptides were designed. The activity of mHG, which was directed by an artificial hydrophobic signal peptide H1 (MMARKIAGMATSLLVIFSSSAVA) from cytoplasm into growth medium, reached 80.56 U/ml after 22-h incubation, indicating that signal peptide hydrophobicity appears to be critical for early stages in mHG export. By purification of the mHG (∼25.3 kDa) from cultures of B. subtilis (pBSG-H1), enzymatic property assays showed that the common optima for mHG were 70°C and pH 5.0. The residual activity of mHG at 90°C for 10 min was 83.45% of its maximum activity, which was almost similar to that of CG (90°C, 10 min, 84.33%). This constructed shuttle expression vector with a novel signal peptide exhibited its applicability for high-level production of heterologous proteins from B. subtilis. Moreover, the high-level secreted mHG with relatively high thermostability could be a potential candidate for feed industrial applications.