A novel protein with alkaline phosphatase and protease inhibitor activities in Streptomyces hiroshimensis

Metagenomic Analysis of Bacterial Communities in Agricultural Soils from Vietnam with Special Attention to Phosphate Solubilizing Bacteria

Bacterial communities can promote increased phosphorus (P) availability for plants and microbes in soil via various mechanisms of phosphate solubilization. The production of extracellular phosphatases releases available P through the hydrolysis of organic P. Examining the abundance and diversity of the bacterial community, including phosphate solubilizing bacteria in soil, may provide valuable information to overcome P scarcity in soil ecosystems. Here, the diversity and relative abundance of bacterial phyla and genera of six agricultural soil samples from Vietnam were analysed by next generation sequencing of the 16S rRNA gene. Phosphatase activities of each soil were compared with physico-chemical parameters and the abundance of the alkaline phosphatase gene phoD. We showed the dominance of Chloroflexi, Proteobacteria, Actinobacteria, Acidobacteria and Firmicutes. Total nitrogen positively correlated with phyla Proteobacteria, Acidobacteria, Firmicutes and Planctomycetes. The abundance of several genera of Proteobacteria showed positive relationship with the copy number of the phoD gene. The abundance of several taxa positively correlated with silt content, while a negative relationship of Proteobacteria was found with sand content. Our results demonstrated the clear influence of soil physico-chemical properties on the abundance of various bacterial taxa including those potentially involved in phosphate solubilization.

Screening for production of proteinase inhibitors by Antarctic Streptomycetes

Three out of 17 Streptomycetes strains - Streptomyces sp. 35 LBG09, Streptomyces sp. 36 LBG09, and Streptomyces sp. 39 LBG09, were selected based on the high production of proteinase inhibitors with trypsin serine proteinase activity. The strains were isolated from soil samples taken from the area around the Bulgarian station on Livingston Island, Antarctica. Biosynthesis of proteinase inhibitors by the promising strains started at different stages of their development but was generally not associated with the growth of the producers. Peak levels were reached in the stationary phase (96-120 h) of their cultivation. Inducing effects on strain development, biomass accumulation, and proteinase inhibitor biosynthesis were based on the composition of the nutrient medium: the polypeptones contained in Taguchi medium and glucose as a carbon source. The most productive out of the three strains was Streptomyces sp. 36 LBG09. Its maximum inhibitory activity was reached at 96 h in culturing media modified by three different carbon sources. The active proteinase inhibitor biosynthesis proceeded at pH values between 6.8 and 8.6 and the dynamics of production depended on the type of carbon source. Peak levels of extracellular protein and dry biomass were reached at 120 h in the stationary growth phase. The residual sugars were minimal at the end of the process when using soluble starch as a carbon source, and maximal when glucose was used.

The histidinol phosphate phosphatase involved in histidine biosynthetic pathway is encoded by SCO5208 (hisN) in Streptomyces coelicolor A3(2)

Through the screening of a Streptomyces coelicolor genomic library, carried out in a histidinol phosphate phosphatase (HolPase) deficient strain, SCO5208 was identified as the last unknown gene involved in histidine biosynthesis. SCO5208 is a phosphatase, and it can restore the growth in minimal medium in this HolPase deficient strain when cloned in a high or low copy number vector. Moreover, it shares sequence homology with other HolPases recently identified in Actinobacteria. During this work a second phosphatase, SCO2771, sharing no homologies with SCO5208 and all so far described phosphatases was identified. It can complement HolPase activity mutation only at high copy number. Sequence analysis of SCO5208 and SCO2771, amplified from the HolPase mutant strain, revealed that SCO5208 shows a mutation in a conserved amino acid, whereas SCO2771 does not show any mutation. All these results show that S. coelicolor SCO5208, recently renamed hisN, is the HolPase involved in histidine biosynthesis.

Purification and characterisation of a protease inhibitor from Streptomyces chromofuscus 34-1 with an antiviral activity

The aim of this study was to purify and characterise a novel protease inhibitor (PISC-2002) isolated from culture supernatants of Streptomyces chromofuscus. PISC-2002 was purified by anion-exchange chromatography, and RP-HPLC analysis. PISC-2002 had a molecular mass of 11.2 kDa and a high content of hydrophobic amino acids and proline. N-terminal sequence gave two sequences differing by one residue. The main sequence is ASLPAVSALVLTV and the shorter sequence is SLPAVSALVLTV. This shows its homology to Streptomyces subtilisin inhibitor family. Besides its large spectrum of powerful inhibitory activities against various serine proteases, PISC-2002 displayed significant antiviral effect against influenza virus A/Rostock/34 (H7N7).