Relationship between the quality of the inoculum material and carminomycin biosynthesis by a culture of Actinomadura carminata]

The effect of the inoculum mycelium quality on carminomycin biosynthesis by Actinomadura carminata was studied. The time of the organism growth on the culture medium containing cornsteep liquor continued for 6 hours without losing by the inoculum of its seeding qualities during that period. The mycelium growth in the inoculum was more intensive under conditions of moderate aeration, i.e. 0.98-2.64 mg O2H1-min. Anincrease in the aeration rate up to 18.56 mg O2/1-min resulted in the growth suppression up to 40 per cent. No correlation between the aeration rate during the inoculum growth and the culture capacity for carminomycin biosynthesis and of the content of the complex in active components the fermentation medium were observed, when a 5-10 per cent of inoculum was used.     

菹草生产力的研究

本文报道了水温、光照度、水的pH值和植株密度对菹草生产力影响的实验结果,以及植株不同部位上的生产力和叶绿素含量的测定值.在光照度8000lx和水温20—28℃的条件下,经51次测定,菹草顶枝的毛产量(P_G)在0.80—1.06毫克氧·小时/0.5克鲜重植物范围,平均值为0.92毫克氧·小时/0.5克;净产量(PN)在0.44—0.79毫克氧·小时/0.5克范围,平均值为0.61毫克氧·小时/0.5克.1小时的平均净光合率为1.11%,1小时的平均呼吸率为0.53%.       

溶氧水平对鳊鱼、中华倒刺鲃幼鱼游泳能力的影响

在(25 1)℃条件下, 以鳊鱼(Parabramis pekinensis)体重(4.70 0.11)g, n=32、中华倒刺鲃(Spinibarbus sinensis)体重(3.26 0.06)g, n=32幼鱼为研究对象, 采用鱼类游泳代谢测定仪在水体溶氧为8、4、2、1 mgO2/L条件下分别测定其临界游泳速度(Ucrit)和游泳代谢率(MO2), 并计算出静止代谢率(MO2rest)、最大游泳代谢率(MO2max)、代谢范围(MS)及单位位移能耗(COT)等相关参数。结果显示, 随着溶氧水平的下降, 鳊鱼、中华倒刺鲃幼鱼的Ucrit均逐渐下降, 除中华倒刺鲃幼鱼的值在4与8 mgO2/L下没有显著性差异外, 其他各组均差异显著(P0.05); 在同一溶氧水平下的中华倒刺鲃Ucrit显著大于鳊鱼(P0.05)。两种鱼的MO2max和MS均随DO的下降而显著下降, 但MO2rest在溶氧水平低于1 mgO2/L才显著下降(P0.05)。研究还发现鳊鱼、中华倒刺鲃幼鱼的MO2在同一游泳速度下随溶氧水平下降而降低, 而在相同溶氧水平下随游泳速度的上升而显著升高(P0.05); COT随游泳速度上升而显著降低(P0.05), 但在高游泳速度下相对稳定, 在同一游泳速度下随着DO的下降有所减小。中华倒刺鲃的COT整体上小于鳊鱼, 且在低游泳速度下差异更大。87.5%(1-8 mgO2/L)溶氧水平的下降导致两种鱼类相似的Ucrit变化(53% vs. 50%), 但溶氧水平由8降到4 mgO2/L时, 鳊鱼32%MO2max的下降导致Ucrit下降13%, 但同样的溶氧水平下降虽然导致中华倒刺鲃的MO2max下降20%, 但由于MO2rest和COT的下降, 其Ucrit并没有显著的变化。实验结果表明: 不同溶氧水平对不同鱼种游泳能力的影响存在差异, 这种差异与其代谢对策密切相关。       

Antibiotic production by a marine isolate (MS 310) in an ultra-low-speed rotating disk bioreactor

Actinomycin-D production by a biofilm-forming estuarine isolate viz Streptomyces sp. MS 310 is studied in small-scale shaken cultures, as well as in a 25 L rotating disk bioreactor, (RDBR) which, when operated at a disk rotational speed of 1 revolution/day with 50% disk submergence, mimics the intertidal conditions of the microbe’s niche estuarine habitat-alternating 12 h periods of inundation and exposure. The ideal pH and temperature for antibiotic production are determined (pH 10, 30°C) through a designed experimental study using shaken flasks. Subsequently, operating conditions in the RDBR are investigated employing a 3ⁿ experimental design wherein each of two (n = 2) parameters viz. aeration and disk submergence are considered at three levels viz high, medium, and low: 9.0, 6.0, and 3.0 L/min for aeration rate; and 75, 50, and 25% for disk submergence, (while maintaining the rotational speed at 1.0 rev/day). The niche-mimic condition along with maximum permissible aeration is found to be most favorable for antibiotic production — peak antibiotic activity (PAA) and peak activity attainment rate (PAAR) simultaneously attaining their highest values: 40 mm and 2.13 mm/h, respectively. Both PAA and PAAR increase with increasing aeration at all operating conditions examined — particularly, at the niche-mimic condition, a threefold increase in aeration rate (3∼9 L/min) causes PAA to increase by 33%, whereas PAAR increases by 2.5 times, thus pointing to the strong aeration dependence of this actinomycin-D producer. Again, compared to the best values obtained in the 500 mL shaken flask experiments, corresponding RDBR values are 16% higher for PAA and more than 5 times higher for PAAR — strong evidence for employing these novel bioreactors for cultivation of antibiotic-producer marine microbes.     

Influence of agitation and aeration on growth and antibiotic production by <Emphasis Type="Italic">Xenorhabdus nematophila</Emphasis>

The effect of agitation and aeration on the growth and antibiotic production by Xenorhabdus nematophila YL001 grown in batch cultures were investigated. Efficiency of aeration and agitation was evaluated through the oxygen mass transfer coefficient (K _L a). With increase in K _L a, the biomass and antibiotic activity increased. Activity units of antibiotic and dry cell weight were increased to 232 U ml⁻¹ and 19.58 g l⁻¹, respectively, productivity in cell and antibiotic was up more than 30% when K _L a increased from 115.9 h⁻¹ to 185.7 h⁻¹. During the exponential growth phase, DO concentration was zero, the oxygen supply was not sufficient. So, based on process analysis, a three-stage oxygen supply control strategy was used to improved the DO concentration above 30% by controlling the agitation speed and aeration rate. The dry cell weight and activity units of antibiotic were further increased to 24.22 g l⁻¹ and 249 U ml⁻¹, and were improved by 24.0% and 7.0%, compared with fermentation at a constant agitation speed and a constant aeration rate (300 rev min⁻¹, 2.5 l min⁻¹).     

Effect of the aeration conditions on the biosynthesis of oxytetracycline and the formation of organic acids by a culture of Actinomyces rimosus]

The effect of the aeration conditions on oxytetracycline biosynthesis and production of organic acids by Act. rimosus was studied. Intensive biosynthesis of oxytetracycline in shaken flasks with concentrated complex media was observed at the rate of oxygen dissolution in the liquid ranging from 14 to 25 mg/1/min. Lower rates of the oxygen dissolution up to 7 mg/1/min resulted in decreased rates of the culture growth and the medium component consumption, decreased antibiotic levels, production of significant amounts of pyruvic and acetic acids.     

A novel circulating loop bioreactor with cells immobilized in loofa (<Emphasis Type="Italic">Luffa cylindrica</Emphasis>) sponge for the bioconversion of raw cassava starch to ethanol

A circulating loop bioreactor (CLB) with cells immobilized in loofa sponge was constructed for simultaneous aerobic and anaerobic processes. The CLB consists of an aerated riser and a non-aerated downcomer column connected at the top and bottom by cylindrical pipes. Ethanol production from raw cassava starch was investigated in the CLB. Aspergillus awamori IAM 2389 and Saccharomyces cerevisiae IR2 immobilized on loofa sponge were placed, respectively, in the aerated riser column and non-aerated downcomer column. Both alpha-amylase and glucoamylase activities increased as the aeration rate was increased. Ethanol yield and productivity increased with an increase in the aeration rate up to 0.5 vvm, but decreased at higher aeration rates. The CLB was operated at an aeration rate of 0.5 vvm for more than 600 h, resulting in an average ethanol productivity and yield from raw cassava starch of 0.5 g-ethanol l(-1) x h(-1) and 0.45 g ethanol/g starch, respectively. In order to increase ethanol productivity, it was necessary to increase the dissolved oxygen (DO) concentration in the riser column and decrease the DO concentration in the downcomer column. However, increasing the aeration rate resulted in increases in the DO concentration in both the riser and the downcomer columns. At high aeration rate, there was no significant difference in the DO concentration in the riser and downcomer columns. The aeration rate was therefore uncoupled from the liquid circulation by attaching a time-controlled valve in the upper connecting pipe. By optimizing the time and frequency of valve opening, and operation at high aeration rate, it was possible to maintain a very high DO concentration in the riser column and a low DO concentration in the downcomer column. Under these conditions, ethanol productivity increased by more than 100%, to 1.17 g l(-1) x h(-1).     

The effect of dissolved oxygen and aeration rate on antibiotic production of Streptomyces fradiae

Different dissolved oxygen concentrations and aeration rates were imposed on a stable mutant of Streptomyces fradiae during the antibiotic-producing phase. At high aeration rate (1 vvm), the tylosin yield in the fermentor broth with dissolved oxygen (DO) concentrations controlled close to 100% saturation (6-8 ppm) increased 10% as against uncontrolled. The rates of cellular growth, oil consumption, and tylosin production were severely reduced when DO concentration fell below 25% saturation, but all resumed to their initial rates when DO was raised to saturation level again. The DO concentration in combination with air flow rate affected the pattern of the antibiotics produced. At high DO levels, an additional macrolide antibiotic, macrocin, was synthesized to more than one-third the amount of tylosin at high aeration rate (1 vvm). On the other hand, tylosin production rate remained constant and no significant amount of macrocin was produced at low aeration rate (0.2 vvm).     

Effect of the aeration and agitation states on tetracycline biosynthesis in semiproduction-capacity apparatus]

The results of the experiments on determination of the effect of aeration and agitation conditions on biosynthesis of tetracycline in the apparatus of semi-production capacity are discussed. It was shown that the antibiotic production level was not connected with the rate of oxygen solution expressed in the sulphite numbers, i.e. this parameter cannot be used as a scaling-up criterion. Accumulation of the antibiotic in the fermentation broth depended on the volume of the air supplied for aeration. It was determined that the level of CO2 dissolved in the fermentation broth did not reach the values having an inhibitory effect on the biosynthetic process.     

Madumycin biosynthesis by an Actinomadure flava culture under conditions of varying aeration]

Production of madumycin I and madumycin II by 2 strains of Actinomadure flava 2171 was studied. Intensive aeration was an obligatory condition for the antibiotic biosynthesis. The content of madumycins I and II in the culture fluid depended on the strain, aeration conditions and fermentation cycle. Strain 2171/852 produced maximum amounts of madumycin I and madumycin II by the 2nd--3rd and 5th days of cultivation respectively. Strain 2171/2544 mainly produced madumycin I during the whole period of fermentation.     

Processes of spore formation and gramicidin C formation by Bacillus brevis var. G.B.]

Correlation between gramidicin C biosynthesis and sporulation in the process of Bac. brevis var. G.B. cultivation under various aeration conditions was studied. It was shown that biosynthesis of gramicidin C was characteristic of the young cells and its level was the highest during the culture active growth. The time of the sporulating forms appearance depended on the aeration rate which defined the quantitative composition of the population during the phase of the culture active growth and the stationary phase. Under the optimal aeration conditions the spore formation started during the phase of the culture active growth after some decrease in the maximum level of the cell productivity with respect to the antibiotic. When the aeration rate was increased the spore formation was shifted to later periods of the culture development, i.e. the stationary phase and the phase of the cell autolysis, the gap between the highest levels of gramicidin C buosynthesis and the beginning of sporulation being increased. Under certain aeration conditions the spore formation was not observed, while gramicidin C was synthesized. A conclusion has been made that there is no correlation between gramacidine C biosynthesis and sporualtion in Bacillus brevis var. G.B.     

Oxygen transfer rates in a mammalian cell culture bioreactor equipped with a cell-lift impeller

Measurements of k(L)a were carried out in 1. 5- and 5-L New Brunswick Scientific CelliGen(R) bioreactors. The measured k(L)a in water were identical for both vessel sizes operated in similar condition. The mass transfer rate increased with temperature, mixing speed, and aeration rate, with this last parameter being the most significant. Surface aeration alone gave k(L)a values of 0. 4 to 1. 6 h(-1). A 25% decrease in k(L)a was observed above an aeration rate of 1. 6 vvm. This was caused by the particular foam breaker of the CelliGen bioreactor. Measurements of k(L)a using a mammalian cell culture medium supplemented with 5% fetal calf serum (FCS) have confirmed the negative effect of the foam breaker on k(L)a The measured value in this medium was 1. 2 h(-1) for all aeration rates, more than 60% of which was attributed to surface aeration.     

三峡水库浮游植物初级生产力的季节变化与空间分布

研究在三峡库区选取秭归、巫山、云阳、忠县、木洞5 个断面, 自2012 年8 月至2013 年4 月采用黑白瓶法进行为期一周年季节性的原位初级生产力测定, 探讨初级生产力的季节变化、水平分布、垂直分布等动态特征。结果表明: 初级生产力平均值(以溶氧计)的四季变化规律为: 夏季5.613 mgO2/(Ld)春季3.630 mgO2/(Ld)冬季0.906 mgO2/(Ld)秋季0.552 mgO2/(Ld), 与浮游植物叶绿素a 含量的季节变化一致;在初级生产力的空间分布上, 5 个断面中库首最高(秭归)、库中次之(巫山、云阳、忠县)、库尾最低(木洞);且全年所有断面干流初级生产力均显著低于支流初级生产力;在垂直分布上, 初级生产力的最大值主要出现在水下0-1 m 间, 在水下1-5 m 随着水深增加呈现递减趋势, 光能可得性可能是限制浮游植物初级生产力的重要因子。相关性分析表明, 毛初级生产力与叶绿素a、溶解氧、pH 呈显著正相关。       

Effect of aeration on lysine biosynthesis in nutrient media with different concentrations of components]

The lysine synthesis by the culture M. glutamicus T-3 on nutrient media with varying molasses concentrations was studied during cultivation under different aeration conditions. With an increase in the nutrient concentration the relationship between the lysine yield and aeration rate became very manifest. An elevation of aeration (Kv) from 1.2 to 6.3 g O2 1/hr increased the yield of lysine in the 15, 20 and 28% molasses medium by 3, 6 and 11 times, respectively. A decline in aeration decreased the biomass yield and increased the content of lactic acid and alanine in the culture liquid (to 19 and 4 g/l, respectively). The rate of respiration of the culture in the filtrate of the culture liquid measured in the Warburg apparatus depended on the cell age and molasses concentration in the nutrient medium and not on the aeration rate.     

Characteristics of aerobic granular sludge in a sequencing batch reactor with variable aeration

Aerobic granules can be used for the treatment of industrial or municipal wastewater, but high aeration rate is required for the stable operation of the granular sludge system. Therefore, the aim of this research was to reduce aeration rate greatly to decrease the energy consumption for the technology of aerobic granules. Based on the characteristics of sequencing batch reactor with distinct feast and famine periods, aeration rate was reduced from 1.66 to 0.55 cm s⁻¹ in the famine period after granules were formed. It was found that the settleability of aerobic granules in reactor R1 with reduced aeration was the same as that of aerobic granules in reactor R2 with constant aeration rate of 1.66 cm s⁻¹. However, the outer morphology of aerobic granules gradually changed from round shape to long shape, and minor population showed certain shift after aeration rate was reduced in the famine period. Since good settleability is the most essential feature of aerobic granules, it can be said that reducing aeration rate in famine period did not influence the stable operation of aerobic granular sludge system. Furthermore, the experimental results indicated that aeration rate in feast period was much more important to the stable operation of aerobic granules than that in famine period.     

Production and partial purification of a peptide antibiotic from Staphylococcus epidermidis

When grown on solid or in liquid Brain Heart Infusion at 37°C, Staphylococcus epidermidis NCIB 11536 produced antibiotic activity against a wide range of Gram positive bacteria. Production was influenced by aeration, pH, glucose concentration and specific growth rate. Inhibitory activity could be concentrated by ammonium sulphate precipitation (30–55% saturation). On Sephadex G50 using 0.05 mol/1 sodium phosphate buffer, pH 6.0, two peaks of antibiotic activity were detected. The first peak eluted with the void volume (K_d= 0) and the second peak was retained by the gel (K_d= 0.73–0.77). These two substances did not represent the monomeric and polymeric forms of a staphylococcal bacteriocin. The low mol. wt inhibitor, which was responsible for over 95% of the recovered activity on Sephadex G50, could be partially purified by a combination of gel filtration on Biogel P2 and ion-exchange chromatography on Sephadex C-25. Yields were increased by combining these two steps into a single procedure (duocolumn). The semi-purified inhibitor was desalted using Sep-pak C₁₈ cartridges. Biological activity was resistant to enzymic denaturation except by high concentrations of trypsin (50 units/μg, 3 h, 25°C). This peptide antibiotic is different from any previously described staphylococcal inhibitors.     

Optimization of the production of virus-like particles in insect cells

In this work the maximal operational hydrodynamic conditions (agitation and aeration rate) that cause no adverse effect in Sf-9 cells growth in SF900II serum-free medium were determined. Shear stresses higher than 1 N m-2 and aeration rates higher than 0.04 vvm affect cell growth and when these conditions increase to 1.5 N m-2 and 0.11 vvm, cell growth is completely inhibited with significant cell morphology changes and a strong decrease in viability. Although the pO2 did not show a significant effect upon cell growth in the range from 10 to 50%, cell infection and specific productivity were dramatically affected. The production was optimal at a pO2 of 25% with decreases higher than 50% being observed when the pO2 decreased to 10 or increased to 50%. The maximum product quality, i.e., the percentage of product in the form of high molecular weight particles, is not coincident with maximum product titer. Although the highest Pr55gag particle titer was obtained at 96 hours post infection (hpi) and at pO2 of 25%, the best product quality (defined by gel filtration chromatography and Western immunoblot) was obtained at 48 hpi, independently of the pO2 used. The effect of overcritical conditions upon productivity was also studied. As obtained for cell growth, cell infection is affected by shear stresses above 1 N m-2 and by aeration rates higher than 0.04 vvm, with decreases in Pr55gag particle titer higher than 70%, even when the overcritical values are still far from the limit at which cell death occurs. The results obtained and the optimization strategy used allowed the maximization of the oxygen supply without damaging the cells, with important consequences on the scale-up of a production process involving this insect cell/baculovirus expression system.     

Effect of aeration and redox potential on the biosynthesis of the antibiotic imbricin]

The relationship between imbricin biosynthesis by Streptomyces imbricatus and the medium aeration and redox potential (Eh) was studied. The influence of the oxygen dissolution velocity within the ranges of 2.9 to 0.5 g O2/l.h was investigated and it was shown that the highest yield of the antibiotic was provided by the maximum velocity. At the background of the intensive aeration (2.9 g O2/l.h) decreasing of Eh by reducing agents such as ascorbic acid, L-thyrosin or K4Fe(CN)6 stimulated the biosynthesis whereas at the lower velocities the process proved to be inhibited. Under conditions of insufficient aeration the biosynthesis stimulation could be provided by increasing the medium Eh by acidifying agents such as K2Cr2O7, K3Fe(CN)6 or KMnO4. It was concluded that intensive synthesis of imbricin required not only efficient aeration but also definite levels of the medium redox potential.     

Sludge ozonation: disintegration, supernatant changes and mechanisms

This paper studied in detail the sludge disintegration and supernatant changes during ozonation and investigated the possible mechanisms. Ozone effectively lysed the sludge. The most important mechanism is proposed to be damages of microorganism cells. The ozone dose of 50 mgO(3)/gDS was found optimal for sludge lysis; 25 mgO(3)/gDS achieved only 10.4% sludge lysis after 90 min and 80 mgO(3)/gSS did not further improve sludge decomposition. When the ozone dose was 50 mgO(3)/gDS, the sludge disintegration degree was 46.7% after 105 min. The sludge solid concentration and volatile solid concentration decreased by 49.1% and 45.7%, respectively. The supernatant soluble chemical oxygen demand, total nitrogen, total phosphorus, protein, polysaccharide, and deoxyribonucleic acid increased by 699%, 169%, 2379%, 602%, 528%, and 556%, respectively. Various components showed quite different patterns. Ozone treatment significantly reduced the sludge bioactivity, decreased the partition coefficients of heavy metals between sludge and supernatant, but did not alter the sludge size distribution.