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The effects of the short-term application of Ascophyllum nodosum-fermented seaweed fertilizer on the bacterial community, soil nitrogen contents, and plant growth in maize rhizosphere soil were evaluated. The changes in the bacterial community composition and nitrogen contents including those of total nitrogen (TN), nitrate nitrogen (NO 3 - -N) and ammonium nitrogen (NH 4 + -N) in rhizosphere soils in response to treatment with seaweed fertilizer were determined. Furthermore, soil enzymatic activity and crop biomass were analyzed. The relative abundance of the dominant phyla varied regularly with fertilization, and bacterial α-diversity was apparently influenced by seaweed fertilizer amendment. The TN contents of all soil samples decreased gradually, and the NO 3 - -N and NH 4 + -N contents of the soils treated with seaweed fertilizer were much higher than those of the control soils. Similarly, the enzymatic activities of dehydrogenase, nitrite reductase, urease, and cellulase in the soil were significantly increased on day 3, day 8, and day 13 after the application of seaweed fertilizer to the maize rhizosphere soil. However, there was no difference in the activity of soil sucrase between the treatment group and the control group. In this study, the growth of maize seedlings was confirmed to be greatly promoted by the utilization of seaweed fertilizer. These results deepen our understanding of plant-microbe interactions in agroecosystems and should benefit the wide use of seaweed fertilizer in sustainable agricultural production.

Lactobionic acid (LBA) is a newly identified natural polyhydroxy acid that is widely used in the food industry. In this study, the antibacterial effects and underlying mechanism of action of LBA against Staphylococcus aureus were investigated. LBA exhibited significant antibacterial activity against S. aureus with a determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 15 mg/mL and 50 mg/mL, respectively. The Growth curves indicated that LBA directly inhibited the growth of S. aureus. Moreover, LBA induced the leakage of alkaline phosphatase and nucleotides in the culture medium, indicating damage to the integrity of the S. aureus cell wall membrane, which was confirmed by transmission electron microscopy observations. The relative electric conductivity measurements indicated that LBA changed the cell membrane permeability. The preservation effect of LBA was evaluated by quantifying the total number of colonies, total volatile base nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS). Overall, these results revealed that LBA exerts its antibacterial activity by breaking down the structure of the bacterial cell wall and membrane, thereby releasing the cellular contents as well as inhibiting protein synthesis, which ultimately lead to cell death. The total number of colonies, the TVB-N value, and the TBARS of cold fresh meat treated with preservatives were significantly lower than those of the control group (P < 0.05). With these antibacterial characteristics, LBA has potential to be used as a safe food additive in the food industry.

The variations in the soil culturable bacterial communities and biochemical parameters of early successional soils from a receding glacier in the Tanggula Mountain were investigated. We examined low organic carbon (C) and nitrogen (N) contents and enzymatic activity, correlated with fewer bacterial groups and numbers in the glacier forefield soils. The soil pH values decreased, but the soil water content, organic C and total N significantly increased, along the chronosequence. The soil C/N ratio decreased in the early development soils and increased in the late development soils and it did not correlate with the soil age since deglaciation. The activities of soil urease, sucrase, protease, polyphenol oxidase, catalase, and dehydrogenase increased along the chronosequence. The numbers of culturable bacteria in the soils increased as cultured at 25°C while decreased at 4°C from younger soils to older soils. Total numbers of culturable bacteria in the soils cultured at 25°C were significantly positively correlated to the soil total N, organic C, and soil water content, as well as the activities of soil urease, sucrase, dehydrogenase, catalase, and polyphenol oxidase. We have obtained 224 isolates from the glacier forefield soils. The isolates were clustered into 28 groups by amplified ribosomal DNA restriction analysis (ARDRA). Among them, 27 groups and 25 groups were obtained from the soils at 25°C and at 4°C incubation temperatures, respectively. These groups are affiliated with 18 genera that belong to six taxa, viz, Actinobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, Alphaproteobacteria, and Betaproteobacteria. The dominant taxa were Actinobacteria, Gammaproteobacteria, and Bacteroidetes in all the samples. The abundance and the diversity of the genera isolated at 25°C incubation temperature were greater than that at 4°C.

The microbial community structure along an altitude gradient was investigated in different localities, in Kalasi lake, Urumqi river and Sangong river, Xingjiang (China). The mean numbers of DAPI (4',6-diamidino-2-phenylindole)-stained cells were lower in Kalasi lake than that in Urumqi river and Sangong river; these differences were attributed to increasing environmental harshness including lower soil organic carbon and nitrogen content, more acidic pH and lower annual temperature. In each locality, the numbers of bacteria and archaea measured with two fluorescence-labeled 16S rRNA oligonucleotide probes (EUB338 and ARCH915) were higher in a coniferous forest and lower in desert vegetation. A significant and positive relationship was found between microbial and soil organic carbon and total nitrogen along the altitudinal gradient, indicating that plant communities and soil nutrients influence the soil microbial structure. The results show that the microbial population in higher latitudinal site was fewer than lower latitudinal one, soil microorganisms were positively correlated to soil organic carbon and total nitrogen, and plant communities had an obviously impact on soil microbes.

Lipopolysaccharides (LPS) of Salmonella typhi strains, isolated from carriers and patients suffering from typhoid fever, were characterised according to their biochemical properties, morphological structure and degree of aggregation of complexes. All preparations of LPS, regardless of their origin, were morphologically heterogeneous. Free electrophoresis and immunoelectrophoresis demonstrated that LPS preparations were composed of components possessing different mobilities in electric fields. LPS of bacterial strains isolated from both carriers and patients, split upon reaction in immunoelectrophoresis with specific antiserum 73, rabbit antiserum to Salmonella typhi Vi Bhatnagar and 0-901 split into anodic and cathodic fractions. The anodic fraction reacted similarly as Vi antigen. LPS from Salmonella typhi Ty-2 yielded only the cathodic fraction, typical for O antigen. LPS from strains which were passaged twice in nutritional medium possessed identical properties as LPS from fresh cultures of Salmonella typhi. Electron microscopy revealed that LPS appears as long bands, rods, ellipsoid forms and amorphous material. Contrary to amorphous material, the bands, rods and ellipsoid forms possessed three-layer structure.

Cultivation of Saccharomyces cerevisiae with a linear nutrient feed was used to test the validity of a mathematical model describing changes in the physiological state of the culture. Markers of these changes were the concentrations of proteins and delta 5,7-sterols in yeast dry mass. The model was used to optimize the production of these sterols with regard to the magnitude and composition of nutrient feed.

The balance of nitrogen and nitrogen compounds in Pleurotus ostreatus, cultivated on waste materials, corn straw and maize residues, was investigated. The results show that this organism has a considerable ability to fix atmospheric nitrogen, fixing 312 g of total nitrogen per 100 kg dry weight. When recalculating with respect to a decrease of the substrate during growth of the organism a value of 9.7 mg per 1 g of the decrease in material is obtained. Fruiting bodies, as well as the produced substrate contain 17-19 amino acids. In the produced substrate the content of the protein nitrogen represents only 30% of the total. It can concluded that Pleurotus ostreatus yields a suitable raw material in the food industry and possibly also a fodder based on the basis of solid, cellulose-containing wastes.