Calorimetric studies of the growth of Desulfovibrio desulfuricans in the presence of nitrocellulose

Calorimetric results indicate that nitrocellulose (NC)-induced changes in the metabolism of Desulfovibrio desulfuricans 1388 are caused by both chemical (nitrate) and physical (biofilm formation) factors. Nitrate added to lactate-based culture medium with nitrocellulose competed for the electron flux from lactate and suppressed the bacterial sulfidogenesis and growth. The presence of an insoluble compound (carbon backbone of the polymer) induced the creation of a biofilm-like structure with its own metabolism.     

Synthesis, structural characterization and antibacterial activity of 2,6-diacetylpyridine bis(benzenesulfonohydrazide) Schiff bases and their copper(II) complexes

2,6-Diacetylpyridine bis(benzenesulfonohydrazide) Schiff bases (L¹, L² and L³) and their Cu(II) complexes of the general formula [CuL·H₂O] were synthesized and characterized by various spectroscopic techniques. The crystal structure of [CuL³·(py)]·py was investigated by single crystal X-ray structure analysis. The Cu(II) cation has near square pyramidal, penta-coordinate geometry. The binegatively charged tetradentate Schiff base is asymmetrically coordinated to the Cu(II) ion via the pyridine N atom, the azomethine N atom, the sulfonyl O atom and the deprotonated hydrazine N atom. There is a pyridine molecule apically coordinated to the Cu(II) ion. All the Schiff bases and their copper(II) complexes were screened by the disc diffusion method against multi-drug resistant (MDR) gram-negative and gram-positive bacteria. The minimum inhibitory concentration (MIC) values were also determined. These results show that the antibacterial activity of the Schiff bases against Methicillin-resistant Staphylococcus aureus (MRSA) is enhanced when they are chelated with the copper(II) ion.     

Total Aseptization of Boar Semen,to Increase the Biosecurity of Reproduction in Swine

The aim of the study was to establish the complete microbiological profile of boar semen (Sus scrofa domesticus) and to choose the most effective antiseptic measures in order to control and optimize AI reproduction in pig farms. One hundred and one semen samples were collected and analyzed from several pig farms. The microbiological profile of ejaculates was determined by evaluating the degree of contamination of fresh semen and after dilution with specific extenders. The bacterial and fungal load of fresh boar semen recorded an average value of 82.41/0.149 × 10³ CFU/mL, while after diluting the ejaculates the contamination value was 0.354/0.140 × 10³ CFU/mL. Twenty-four germs (15 bacterial and 9 fungal species) were isolated, the most common being Candida parapsilosis/sake (92%) and Escherichia coli (81.2%). Modification of the sperm collection protocol (HPBC) reduced contamination in raw sperm by 49.85% in bacteria (significant (p < 0.00001) and by 9.67% in fungi (non-significant (p < 0.111491). The load in bacteria and filamentous fungi can be controllable, but not in levuras fungi. Some fluconazole-added extenders (12.5 mg%), ensure fungal aseptization, and even an increase in sperm progressivity (8.39%) for at least a 12 h shelf life after dilution. Validation of sperm aseptization was done by maintaining sow fecundity unchanged after AI (insignificant p > 0.05).     

Antibacterial activity of cyclo(L-Pro-L-Tyr) and cyclo(D-Pro-L-Tyr) from Streptomyces sp. strain 22-4 against phytopathogenic bacteria

Two bioactive cyclic dipeptides, cyclo(L-Pro-L-Tyr) and cyclo(D-Pro-L-Tyr), were isolated from the culture broth of Streptomyces sp. strain 22-4 and tested against three economically important plant pathogens, Xanthomonas axonopodis pv. citri, Ralstonia solanacearum and Clavibacter michiganensis. Both cyclic dipeptides were active against X. axonopodis pv. citri and R. Solanacearum with MIC of 31.25 μg/mL. No activity could be observed against C. michiganensis.     

优良发酵果蔬原酱专用乳酸菌的筛选及鉴定

采用目的平板梯度稀释法,从自然发酵果蔬原浆及中外泡菜老液中分离到22株乳酸菌。采用MRS(pH2.0)初筛平板和MRS(30%葡萄糖)复筛平板,筛选出4株耐酸、耐高糖乳杆菌。对其进行了pH值、酸度、活菌数等果蔬酱发酵性能测试研究,其中两株发酵产酸速度快、发酵性能优异、发酵果蔬酱风     

Preparation, characterization and biological activity of Schiff base compounds derived from 8-hydroxyquinoline-2-carboxaldehyde and Jeffamines ED

Polyethers with 8-hydroxyquinolin-2-yl end groups (HOQCHN-POE-NCHQOH) were prepared by reaction between polyethers having amino end groups (Jeffamines ED^®) and 8-hydroxyquinoline-2-carboxaldehyde. The HOQCHN-POE-NCHQOH polymers were characterized by size-exclusion chromatography, UV, IR, 1H and 13C NMR spectroscopy, and MALDI-TOF mass spectrometry. The complexation between HOQCHN-POE-NCHQOH and Fe³⁺ was studied by UV, IR spectroscopy and differential scanning calorimetry. The UV-irradiation of the complexes caused photodegradation of the polyether chains. It was shown that HOQCHN-POE-NCHQOH had high efficacy on remedying iron-deficient maize plants and exhibited very low-antibacterial activity towards non-pathogenic soil bacteria (B. subtilis).     

CONCENTRATION, SOURCE OF MANGANESE AND IRON IN FERROMANGANESE NODULES AND THE RELATIONSHIP BETWEEN NODULES AND SEDIMENTARY ENVIRONMENTS IN NORTH PACIFIC REGION

The concentration, source of manganese and iron in ferromanganese nodules and therelation between nodules and sedimentary environments are discussed in detail by asynthetical study on chemical information of ferromanganese nodules and correspondingsediment, pore water and geological, biological (bacteria) information in 26 stations fromthe North Pacific region (7- 13°N, 178- 165°W). The result shows that (i) the concen-tration and distribution characteristics of magnese and iron in ferromanganese nod-ules differ in different types of nodules, however, the concentration decreases with theincrease in grain sizes of nodules; (ii) the source of iron in different types of nodulesis basically the same, i. e. the slow sedimentation of overlying water; (iii) manganesein nodules comes mainly from the diffusion of Mn~(2+) in the pore water, and Mn~(2+) fromthe reduction of Mn~(4+) in sediments by the medium of bacteria. As the distribution of bac-teria is believed to be strongly affected by the sedimentary envi     

Chromatographic determination of phosphine (PH3) and hydrogen sulfide (H2S) in the headspace of anaerobic bacterial enrichments using flame photometric detection

Summary A gas chromatographic method is presented which distinguishes phosphine from hydrogen sulfide and other possible headspace gases of anaerobic microbial cultures. In anaerobic cultures spiked with phosphine, this gas is recovered in the liquid and gaseous phase down to 10 pg per ml of gas or liquid. No biogenically produced phosphine was found. Phosphine in amounts as small as 30 ng per 1 can be stored for several days in glass bottles covered with rubber septa, filled with nitrogen, in the presence or absence of water or of an anaerobic bacterial culture. Due to the selectivity of the detector and the retention characteristics of the porous layer open tubular polymer column alkanes, alkenes and organosulfur compounds routinely found in anaerobic bacterial headspaces do not interfere with the analytical quantification of phosphine.     

甲基营养细菌No1甲胺脱氢酶的纯化和性质研究

甲基营养细菌Ｎｏ１甲胺脱氢酶是以色氨酸－色氨酰醌为辅基的一种特殊氧化还原酶．粗酶液经纯化后，其比活力和收得率分别为５．１ｎｍｏｌ·ｇ－１和２８％．该酶的分子量为６７０００，等电点为８．３和８．５，组成它的大、小两个亚基的分子量分别为３７０００和１５０００．甲胺脱氢酶有较好的耐热性，它能催化包括一级甲胺和二胺在内的底物反应，与甲胺反应的Ｋｍ值为２６．６μｍｏｌ·Ｌ－１，最适ｐＨ为８．０．其酶催化反应可被Ｃｕ２＋抑制．该酶的吸收光谱是，在３２８ｎｍ和４２６ｎｍ呈现两个特征峰