[en] The adhesion of yeast (Saccharomyces formesences) cells on polymers was studied thermodynamically. The polymers were laminally prepared by means of radiation polymerization. By measuring contact angles, we calculated dispersion component and polar component of surface free energy of the polymers and the cells, and interfacial free energy between the polymer and the cells. Then interfacial free energy change of the cell adhesion to surface of the polymer was evaluated. The adhesion behavior of yeast cells on the polymers was observed by optical microscope. From above results, we conclude that the initial adhesion of the cells is related to the surface free energy of the polymer, but the irreversible adhesion may be close to the polar component in surface free energy. The high polar component is favourable the irreversible adhesion of yeast cells. (author)

No abstract available

[en] Cationic-hydrophobic copolymer and anionic-hydrophobic copolymer was covered onto surface of paper by radiation polymerization. The paper covered with ionic copolymer was used as carrier of immobilizing Trichoderma reesei cells. Results showed that the cells were immobilized firmly on the carriers and not dislocated from the carriers by shaking. All of FPA of the cells immobilized with the carriers covered with cationic copolymer were higher than that of un-immobilized free cells. The carriers covered with anionic copolymer showed good effect on immobilization of the cells. The weight of immobilized cells increase as increasing the component of DEAEMA in poly (DEAEMA-ATMPT) or decreasing the component of AA in poly (AA-ATMPT). It also increase with the increase of water absorption in poly (DEAEMA-ATMPT) or decrease of water absorption in poly (AA-ATMPT). It shows the static interaction play an important role in the immobilization of cells with ionic copolymer materials

[en] The fresh keeping period of strawberry irradiated with 4.0 kGy dose and stored at room temperature was prolonged to 6 days. Further experiment showed that the irradiation treatment decreased the number of mold in strawberry by two orders of magnitude, inhibited the strawberry fruit respiration and water loss, therefore, improved the effect of strawberry fresh-keeping

[en] Bacillus amyloliquefaciens ES-2 was implanted with 20 keV N⁺ ion beam to breed mutants of high yield of antimicrobial lipopeptides. The dose effects of the nitrogen ion implantation on the survival and positive mutations rate was studied. The mutant strain designated as B. amyloliquefaciens ES-2-4 showing higher yield of antimicrobial lipopeptides was obtained. The concentration of the lipopeptides in fermentation liquid increased by 15.2% compared with the original strain. The authors also studied the fermentation process between the mutant and the original strain. It indicated that the mutant with shorter lag phase, longer stable phase and higher yield of the lipopeptides, which was suitable for large-scale production. (authors)

[en] Protopectinase will be of potential use in industry. The strain of protopectinase-producing Aspergillus sp. XZ-131 was mutagenized by 15 keV N⁺ ion implantation, with a dose range of 0.52 x 10¹⁵ ion/cm² to 4.68 x 10¹⁵ ion/cm². From the ion implanted Aspergillus sp. XZ-131, the Strain Z-25, which yields high activity protopectinase, was screened out. The protopectinase activity increased by 179% and the protopectinase (U/g dry cell) increased by 84%. In addition, the exponential phase of Aspergillus sp. Z-25 was 24 hours shorter than the Strain XZ-131. The Aspergillus sp. Z-25 yielded high protopectinase activity during stationary phase, the highest protopectinase activity was achieved after 72 h fermentation. (authors)

[en] N⁺ ion implantation was used to obtain higher-yield antimicrobial substance. Bacillus subtilis fmbJ was mutated by 25 keV N⁺ ion implantation with the dose of 50 x 2.6 x 10¹³, 80 x 2.6 x 10¹³, 100 x 2.6 x 10¹³, 120 x 2.6 x 10¹³ and 150 x 2.6 x 10¹³ N⁺/m². Results showed that the optimal N⁺ ion dose was 50 x 2.6 x 10¹³ N⁺/m², and a strain of high-yield antimicrobials was obtained and named as Bacillus subtilis fmbJ224. Its antimicrobial substance yield was increased by 96% than the initial. The fermentation characteristic of the strain was studied, and the mode of producing antimicrobial substance for the selected strain was arrearage synthesis type. (authors)

[en] In order to improve the yield of LI-F type antibiotics produced by Paenibacillus polymyxa JSa-9, three different methods including 1-methyl-3-nitro-1-nitroso-guanidin (NTG), ⁶⁰Co-γ rays and low energy N⁺ ion implantation were used for mutation of starting strain JSa-9. The optimal mutagenesis concentration of NTG and dose of ⁶⁰Co-γ ray were respectively identified as 50 μg·mL^-1 and 200 Gy. When the low energy N⁺ ion implantation energy were 10 keV or 20 keV, the optimal injection time were separately 60 and 30 s. By using of NTG mutation a phenylalanine auxotrophic strain N1-37 and a histidine auxotrophic strain N2-27 were ultimately screened out from 300 mutant strains. Staphylococcus aureus was used as a target strain for the inhibition experiment, the results showed that the inhibition zone diameters of strain N1-37 and N2-27 respectively increased 45.54% and 32.35% compared with starting strain JSa-9. By the methods of HPLC the yield of LI-F type antibiotics were determined. The results indicated that the yields of LI-F type antibiotics produced by strain N1-37 and strain N2-27 were respectively 1.71-fold and 1.4-fold of strain JSa-9. The two mutant strains were continuously subcultured for 10 generations and showed good genetic stability. The results obtained here showed strain N1-37 and N2-27 not only had the potential for industrial productions, but also could be used as the parent strains for the cell fusion research. (authors)

[en] The mixture of an ionic monomer of 2-acrylamido 2-methylpropane-sulfonic acid and a series of polyethylene glycol dimethacrylate monomer were polymerized at-78 deg C with ⁶⁰Co γ-rays and were used for immobilization of yeast cells. The immobilized yeast cells with these carriers had higher ethanol productivity than that without any carriers. The yield of ethanol with poly TBAS-14G carrier was the highest, and increased by 3.5 times compared with the free yeast cells. It was found that the ethanol yield increased with the increase of the glycol number in polyethylene glycol dimethacrylate. The state of the immobilized cells was observed with microscope and it was found that the difference in the ethanol productivity was mainly due to the difference in the internal structure and the properties of polymer carrier. It was considered that the polymer carrier had a proper hydrophilicity, swelling ability, cation in the surface and porousity in the internal structure for immobilizing yeast cells

[en] Radiation screened 98 isolates from 3032 cfu on 56 infusion sets were studied for radiation resistance. The D₁₀ values of these screened isolates were 0.8 to 4.0 kGy and mostly ranged within 1.2 to 1.6 kGy. The microorganisms with D₁₀ ≤ 1.6 kGy were about 99.0% of the total bio-burden. All of the screened isolates were gram-positive bacteria, and 84 isolates were classified as Bacillus sp. and 14 isolates were characterized as Micrococcus sp.. One isolate with D₁₀ of 4.0 kGy (from D-6 = 24 kGy) was found outside of the infusion sets, accounting for 0.033% of the total bio-burden. The most resistant bacteria were orange colony and were classified as a Micrococcus sp. with broad shoulder