Plant Growth Promotion and Root Colonization by EPS Producing Enterobacter sp. RZS5 under Heavy Metal Contaminated Soil.

The heavy metal resistant bacterium isolated from field soil and identified as Enterobacter sp. RZS5 tolerates a high concentration (100-2000 mM) of various heavy metal ions such as Mn2+, Ni2+, Zn2+, Cu2+, CO2+ and Fe2+ when grown in such environment and produces exopolysaccharides (EPS). Here, we have demonstrated EPS production by Enterobacter sp. RZS5 during 60 h of growth in yeast extract mannitol broth (YEMB). The yield increased by two fold after the addition of 60 M of Ca2+; 50 M of Fe2+ and 60 M of Mg2+ ions in YEMB, and the optimization of physico-chemical parameters. EPS was extracted with 30% (v/v) of isopropanol as against the commonly used 50% (v/v) isopropanol method. EPS-rich broth promoted seed germination, shoot height, root length, number of leaves and chlorophyll content of wheat (Triticum aestivum) and peanut (Arachis hypogaea) seeds. The higher colony-forming unit of Enterobacter sp. in soil inoculated with EPS rich broth of Enterobacter sp. indicated the root colonizing potential and rhizosphere competence of the isolate. The FTIR spectra of the EPS extract confirmed the presence of the functional group characteristics of EPS known to exhibit a high binding affinity towards certain metal ions. This overall growth and vigour in plants along with the effective root colonization, reflected the potential of the isolate as an efficient bio-inoculant in bioremediation.

A comparative study on the effect of BCG-PSN and thymopeptides on T-lymphocyte subsets of normal and immunosuppressed mice / 华中科技大学学报（医学）（英德文版）

To compare the effects of polysaccharide nucleic acid fraction of bacillus calmette guerin (BCG-PSN) and thymopeptides on T-lymphocytes of normal and immunosuppressed mice, CD4+ and CD8+ T-lymphocyte subsets of single nucleic cell in thymus, spleen and peripheral blood were detected successively by flow cytometry after application of BCG-PSN and thymopeptides. Meanwhile, CD4+/CD8+ ratio was also calculated. The results showed that both BCG-PSN and thymopeptides could decrease the proportion of CD4+ CD8+ T-lymphocyte subsets in the thymus, at the same time increase CD4+ T-lymphocyte, CD8+ T-lymphocyte proportion in the three tissues. The fluctuation in amplitude was greater in thymopeptides group than that in BCG-PSN group. It is concluded that acting location of thymopeptides is in thymus, its stimulating action is stronger than that of BCG-PSN, while BCG-PSN not only accelerates the differentiation in thymus, but also has some direct stimulation to peripheral CD4+ T-lymphocytes, and can maintain CD4+/CD8+ ratio within normal range. So, BCG-PSN is safer.

Chromotropic character of bacterial acidic polysaccharides: Part II--Induction of metachromasy in cationic dye pinacyanol chloride by Klebsiella K10 capsular polysaccharide.

The acidic capsular polysaccharide isolated from Klebsiella K10 exhibited chromotropic character with respect to induction of metachromasy in the cationic dye pinacyanol chloride (1-ethyl-2-[3-(1-ethyl-2(1H)-quinolylidene)propenyl]quinolinium chloride). Klebsiella K10 polymer consists of hexasaccharide repeating units containing one residue of glucuronic acid along with other neutral sugars in each repeating unit. It induces a metachromatic blue shift in the visible absorption spectrum of the dye from 600 nm to 500 nm. The spectral changes have been studied during interaction of the dye cations with the polyanions at different polymer/dye molar ratios. The polyanion-dye compounds are formed with polymer/dye stoichiometry of 1:1, indicating formation of stacking conformation. The complete reversal of polymer-induced metachromasy has also been observed by the addition of ethanol and urea.