Apophysomyces jiangsuensis sp. nov., a Salt Tolerant and Phosphate-Solubilizing Fungus from the Tidelands of Jiangsu Province of China

A newly isolated phosphate-solubilizing fungus from the topsoil of Spartina alterniflora habitats in Yancheng coastal salt marsh was cultivated. Scanning electron microscopy observation revealed that the sporangia are nearly spherical, peach-shaped, and the spores formed on the top of sporangia. The spores are ellipsoidal with raised white nubbins on the surface. Based on a polyphasic study and the genetic distance analysis referring to the sequence analysis of ITS (ITS1 + 5.8S + ITS2) and 28S rDNA (D1/D2 domains) genes, the novel species belongs to the genus Apophysomyces and is named as A. jiangsuensis. The optimum growth temperature and salinity of the new species were 28 °C and 1.15% NaCl, respectively. A study of its phosphate-solubilizing ability revealed that the fungus had an obvious decomposition effect on lecithin, Ca3(PO4)2, and AlPO3, respectively. The pH of the fermented liquid progressively decreased from 6.85 to 2.27 after 7 days of incubation, indicating that the low molecular weight organic acids excreted into the culture liquor were oxalic, succinic, and malic acids and a trace amount of citric acid. Among these, oxalic acid was the major organic acid, and its amount reached 652.5 mg/L. These results indicated that the main mechanism underlying the dissolved phosphorus was related to the secretion of large amounts of organic acids.

High-Throughput Method for Rapid Induction of Prophages from Lysogens and Its Application in the Study of Shiga Toxin-Encoding Escherichia coli Strains

ABSTRACT A high-throughput 96-well plate-based method for the rapid induction of endogenous prophages from individual bacterial strains was developed. The detection of endogenous prophages was achieved by the filtration of the culture liquor following norfloxacin induction and subsequent PCRs targeting bacteriophage-carried gene markers. The induction method was tested on 188 putative Shiga toxin (Stx)-producing Escherichia coli (STEC) strains and demonstrated the ability to detect both lambdoid and stx-carrying bacteriophages in strains for which plaques were not observed via plaque assay. Lambdoid bacteriophages were detected in 37% of the induced phage preparations via amplification of the Q gene, and Stx1- and Stx2-encoding phages were detected in 2 and 14% of the strains, respectively. The method therefore provided greater sensitivity for the detection of Stx and other lambdoid bacteriophage populations carried by STEC strains than that for the established method of plaque assay using bacterial indicator strains, enabling, for the first time, large-scale bacteriophage population and diversity studies.

Simultaneous production of three phenazine pigments by Pseudomonas aeruginosa Mac 436

Pseudomonas aeruginosa Mac 436 was found to produce simultaneously three phenazine pigments identified as pyocyanine, phenazine-1-carboxylic acid, and oxychlororaphine. Production of these pigments on various media indicated a wide variation in yields depending on the composition of the media, but satisfactory yields of all three pigments were obtained. A scheme was developed for separation and assay of the pigments from the culture liquor. Details of production, isolation, assay, and identification are given.