A two-stage cultivation process for the growth enhancement of Chlorella vulgaris

This study proposes a two-stage cultivation process with an autotrophic growth followed by a mixotrophic process. The results indicated that a two-stage cultivation process using a daily dose of 3 g/L of glucose could achieve 7.4 g/L of biomass, which was about a 64 % increase over simple autotrophic cultivation. In the second stage of mixotrophic cultivation, glucose was regarded as a better carbon source for cell growth, than was glycerol. Linoleic acid (C18:2) would be the primary component in the two-stage cultivation as in the autotrophic cultivation. Even carbon source was provided in the second stage of mixotrophic cultivation; lower light intensity limited the mixotrophic growth, which indicated that photosynthesis still plays an important role in the second stage of mixotrophical cultivation. The final biomass was higher after this two-stage cultivation process, which made it suitable for application in the production scale-up of algal biomass.     

Biosynthesis of citric acid by Yarrowia lipolytica repeat-batch culture on ethanol

After analysis of batch culture and identification of the ways for prolongation of citric acid active synthesis by yeast, repeat-batch (RB) cultivation was suggested. Yarrowia lipolytica strain RB cultivation was studied and optimal conditions for cultivation selected. It was shown that when applying RB cultivation, better results were obtained than for batch cultivation. The activity of the culture remained stable after cultivation for more than 700 h. Comparative analysis of enzyme activities confirmed the regularity of the effect described, as the activity of practically of all the enzymes participating in ethanol oxidation and citric acid biosynthesis remained stable over time during RB cultivation. Advantages of RB cultivation for the production of citric acid by yeast are discussed. Received: 1 March 1999 / Received revision: 28 June 1999 / Accepted: 5 July 1999     

Biosynthesis of amylolytic enzymes during continous cultivation of the yeast-like fungus Endomycopsis fibuliger 55-13

Growth of the yeast-like fungus Endomycopsis fibuliger 55-13 during continous cultivation was studied. The microorganism produced amylolytic enzymes during flow cultivation. As a result of the three-stage cultivation the productivity increased two-fold and the time of cultivation decreased by 6 hrs as compared with periodic cultivation.     

Comparative analyses of viable bacterial counts in foods and seawater under microplate based liquid- and conventional agar plate cultivation: increased culturability of marine bacteria under liquid cultivation

Bacterial counts under liquid cultivation using 96-well microplates were performed. The counts under liquid and under solid cultivation were equivalent in foods, although the counts under liquid cultivation exceeded those under solid cultivation in seawater, suggesting that some bacteria in seawater were viable but did not form detectable colonies. Phylogenetic analysis of bacteria obtained under liquid cultivation was also performed.     

鸡枞的驯化栽培现状

本文论述了当前鸡枞菌驯化栽培的两种模式即:以培养鸡枞菌为重心的腐生菌模式、以扩繁鸡枞菌共生白蚁为重心的原生态模式,并对其驯化栽培过程中所面临的问题及其可能的解决方案进行了阐述。     

不同栽培模式黄山药新根茎生长量的比较研究

本文研究了3种栽培模式(农业栽培模式、苹果园栽培模式和灌丛林带栽培模式)对黄山药新根茎生长量的影响,分析了3种模式的利弊和规模化发展黄山药的可能性,为多途径规模化发展黄山药提供了理论依据和技术范例。     

川东南高温伏旱区杂交中稻超稀栽培对稻米整精米率的影响与组合间库源结构的关系

以18个杂交中稻组合材料,研究了超稀栽培与传统栽培间稻米整精米率的变异与组合间库源结构的关系。结果表明:中小穗型组合在超稀栽培条件下的整精米率会明显改善,而大穗型组合的整精米率反而降低。其原因在于中小穗型组合在传统栽培条件下的叶粒比和灌浆速率较高,改为超稀栽培后,叶粒比和灌浆速率明显降低,相对提高了籽粒容重,近而提高了整精米率。大穗型组合在传统栽培条件下的叶粒比和灌浆速率较低,改为超稀栽培后,叶粒比和灌浆速率进一步明显降低,此时因库源比例失调,源明显不足以致籽粒充实度差,从而相对降低了籽粒容重和整精米率。超稀栽培应选用传统栽培条件下着粒数不超过177粒的组合为宜。     

Application of terminal restriction fragment length polymorphism (T-RFLP) analysis to monitor effect of biocontrol agents on rhizosphere microbial community of hot pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.)

Microbial communities in hot pepper (Capsicum annuum L.) cultivation fields under different cultivation methods were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis. Rhizosphere soil and leaf samples were collected from control, conventional and nature-friendly cultivation fields between May and July, 2009. Two Bacillus subtilis strains were applied to nature-friendly cultivation fields as biocontrol agents during the sampling period. Relative abundances of bacteria and plant pathogenic fungi related T-RFs were also measured to monitor the effect of biocontrol agents on potential plant pathogenic fungi. In the principal component analysis (PCA) based on T-RFLP profiles, the microbial communities from rhizosphere soil samples in July, including bacteria and fungi, showed distinct difference between nature-friendly cultivation fields and other cultivation fields. However, there was no correlation between cultivation methods and leaf microbial communities at any sampling period. Changes in the abundance of bacteria related T-RF in the rhizosphere of nature-friendly cultivation fields were observed clearly two months after application of biocontrol agent, while the abundance of plant pathogenic fungi related T-RFs significantly decreased.     

Much Improved Water Use Efficiency of Rice under Non-Flooded Mulching Cultivation

Water shortage is increasingly limiting the luxury use of water in rice cultivation. In this study, non-flooded mulching cultivation of rice only consumed a fraction of the water that was needed for traditional flooded cultivation and largely maintained the grain yield. We also investigated the growth and development of rice plants and examined grain yield formation when rice was subjected to non-flooded mulching cultivation. One indica hybrid rice combination was grown in a field experiment and three cultivation methods, traditional flooding （TF）, non-flooded straw mulching cultivation （SM） and non-flooded plastic mulching cultivation （PM）, were conducted during the whole season. Grain yield showed that there was no significant difference between SM and TF rice, but the grain yield of SM cultivation was significantly higher than that of PM. The tiller numbers were inhibited in the early stage under non-flooded mulching cultivation, but the situation was reversed at the later period. Both SM and PM rice reduced dry matter accumulation of shoot, but increased root dry weight, enhanced the remobilization of assimilates from stems to grains and increased the harvest index. During the middle and later grain filling period, mulched plants showed a faster decrease in chlorophyll concentrations, photosynthetic rates of flag leaves and root activity than TF rice, indicating that non-flooded mulching cultivation enhanced plant senescence. In comparison, SM treatment produced higher grain yield and, more dry matter accumulation and panicle numbers than the PM treatment. The overall results suggest that high yield of non-flooded mulching cultivation of rice can be achieved with much improved irrigaUonal water use efficiency.     

From natural woodlands to cultivated land: diversity of fruit‐feeding butterflies and beetles in the mid‐Zambezi valley,northern Zimbabwe

We tested the effect of cultivation on butterfly (Nymphalidae: Charaxes) and beetle (Coleoptera: Scarabaeidae: Cetoniinae) species richness and abundance along a cultivation intensification gradient. Results showed significant differences in species richness and abundance between natural woodlands and cultivated landscapes with larger differences in areas of high cultivation intensity. The results indicate that natural woodland clearing for cultivation purposes has negative impacts on arthropod diversity, a situation more severe in highly intensified cultivated areas. Our results imply that mosaics of different land‐use units, each in a different phase of clearance‐cultivation‐abandonment‐recovery‐clearance cycle could counter the negative effects of cultivation intensity on arthropod diversity.     

Cultivation and Conservation in Ngorongoro Conservation Area, Tanzania

Ngorongoro Conservation Area (NCA), Tanzania, contains renowned wildlife, an expanding human population, and cultivation by Maasai agro-pastoralists and non-Maasai agriculturalists. We used integrated assessments to explore some effects of cultivation on livestock, resident wildlife, and people. Using a Landsat image from 2000, we mapped 3,967 ha [9,803 acres (ac)] of cultivation within NCA, or 39.7 km² of the 8,283 km² conservation area. Using integrative ecosystem (Savanna) and household (PHEWS) models, we assessed effects of: up to 50,000 ac (20,234 ha) of cultivation; cultivation concentrated into two blocks totaling 10,000 ac (4,047 ha) and 20,000 ac (8,094 ha) that may be more palatable to tourists; and human population growth. Simulations with from 10,000 to 50,000 ac in cultivation showed no large changes in ungulate populations relative to there being no cultivation. When cultivation was altered to be in two blocks, some wildlife populations changed (≤15%) and ungulate biomass remained the same. When cultivation was increased linearly with human population, poor households needed 25% of their diets to come from relief as populations tripled, because livestock could not increase significantly. Our results indicate that having <1% of NCA in cultivation, in its current distribution, is not overly detrimental to wildlife or livestock populations, and is important to Maasai well-being.     

Oxygen tolerance in anaerobic pathogenic bacteria

A prerequisite for successful identification of anaerobic pathogenic bacteria from samples of clinical material is the method of cultivation. Currently, several methods of cultivation in anaerobic environment are used: cultivation in anaerobic box, anaerobic jar, and in nonrecurring cultivation system. Here, we determined the suitability of the above methods of cultivation using the estimation of the growth (diameters of colony size) of commonly isolated anaerobic pathogens (Bacteroides fragilis, Clostridium difficile, and Clostridium perfringens). The tested bacterial strains were exposed to atmospheric oxygen for various time periods and then they were cultivated using different anaerobic cultivation systems. Maximum growth differed, depending on the type of cultivation and the strain used. Thus, largest zone diameters, in the majority of measurements, were achieved in the anaerobic box. However, nonrecurring cultivation system seemed better in several cases; this applied to the cultivation of C. perfringens after 15, 30, and 60 min exposure to atmospheric oxygen as well as the cultivation of B. fragilis after 30 and 60 min of oxygen exposure. The cultivation in anaerobic box was the most convenient method for growth of C. difficile. In almost all cases, higher growth was observed in nonrecurring cultivation system than in the system of anaerobic jar. On the other hand, no significant differences were observed among these anaerobic cultivation systems which confirmed their applicability (taking into account some individual features concerning the optimization of cultivations) for identification of pathogenic anaerobes.     

The microbial population in the air of cultivation facility of oyster mushrooms

The microbial population in the air of mushroom cultivation facility was studied to understand the population structure and size depending on the cultivation methods and regions. The air contents of ten farmers’ oyster mushroom cultivation facilities in Kyunggi province were sampled. The results indicated that there was no difference in population size depending on the regions of mushroom cultivation. In addition, the population size of bacteria in the growth room was bigger than that of the cooling room and outside of the mushroom house, but the fungal population was similar in size between cultivation stages. With regard to population structure, Pseudomonas and Penicillium species were most frequently isolated from the air of oyster mushroom cultivation facility.     

不同栽培条件下南方红豆杉生长特性研究

以4～6年生南方红豆杉为材料,对其不同栽培条件下地径、冠幅、株高、当年抽高、当年侧枝数及总侧枝数等生长特性进行了研究。结果表明:南方红豆杉4～6年生幼林生长量随年龄增大而增加,但其增加的趋势变缓,生长速度变慢;耕作农田中南方红豆杉生长最好,土壤板结未耕作农田生长较差,去除上层20cm耕作土的农田最差;南方红豆杉纯林生长好于落叶阔叶林下(林分郁闭度0.6～0.7),且种植密度越大差异越明显;南方红豆杉落叶阔叶林下套种及纯林生长量均随栽培密度减小而增大,不同栽培密度相差越大,生长量差异越明显。     

Optimization of costs per unit of microbial biomass produced in a batch culture

The time course of costs per unit mass of produced biomass is calculated under the assumption that the production costs during the cultivation of microorganisms are proportional to the cultivation period. The costs are shown to attain a minimum during the cultivation. The cultivation period corresponding to this minimum is calculated in the case when the time dependence of miorobial concentration in a culture can be expressed explicitly.     

利用培养和免培养方法研究红壤的真菌多样性

利用培养和免培养方法研究了一个云南红壤的真菌多样性。扩增的18S rRNA基因片段经过RsaⅠ、HinfⅠ、HaeⅢ三种限制性内切酶消化后,培养方法共获得16种限制性酶切长度多态类型（Restriction Fragment Length Polymorphism,RFLP）,而免培养方法仅获得了12种RFLP类型。每个代表类型经DNA测序及系统发育分析表明,免培养方法得到的真菌全部属于子囊菌门。优势物种与Aspergillus niger类似,占免培养真菌的40．9％。其次是Penicillium属和Paecilomyces属真菌,分别占免培养真菌的18％和17％。此外,有13个克隆仅和环境克隆具有较近的亲缘关系。培养方法获取的真菌包括Ascomycota门（11．5％）、Zygomycota门（86．5％）以及Basidiomycota门（1．9％）真菌,优势克隆来自Mortierella属,占全部培养克隆的55．8％,有21．2％的序列与Absidia glauca相似。两种方法观察到的真菌物种完全不同。     

Bisource carbon dioxide feeding of the photosynthetic process of microalgae autotrophic cultivation

The mechanism of carbon dioxide saturation of alkaline nutrient medium for the purpose of autotrophic cultivation of microalgae is studied. Carbon dioxide desorption from aqueous solutions of sodium hydrocarbonate is investigated and the influence of chemical equilibria in the solutions on the cultivation of carbon dioxide supply is discussed. It is pointed out that these solutions can be considered to be carriers of the assimilable carbon source for the microalgae cultivation, most efficient at pH 8.5. A comparative estimation of the carbon dioxide and the hydrocarbonic ion as assimilable components of the chemical equilibria under study was done, leading to the conclusion that the more probable component in an alkaline medium autotrophic microalgae cultivation is carbon dioxide. A scheme of bisource feeding of the photosynthetic process, with carbon dioxide for the autotrophic microalgae cultivation in a alkaline nutrient medium, providing a stable and economical cultivation process, is proposed.     

Artificial sporeling and field cultivation of Gelidium in China

The supply of Gelidium resources is dependent on collection from natural habitats. As these resources are very limited, one possible means of augmenting production is by implementation of artificial cultivation as has been done with Laminaria, Porphyra and Eucheuma. Chinese phycologists have conducted research on sporeling and field cultivation of Gelidium for many years. Trials have been made using: (1) raft cultivation based on vegetative propogation of thallus fragments, (2) cultivation based on spore-collecting and land-based tank culture to provide seedstock, (3) cultivation based on regeneration from small thallus fragments to provide seedstock. Some of these results have been promising, but development remains at the experimental stage and methods of cultivation need to be improved. This paper is an updated review of the research and development on artificial sporeling production and field cultivation of Gelidium in China.     

Kinetics of continuous cultivation

Kinetic, studies were made on continuous cultivation applying the theory of microbial cell growth that was derived previously by the authors introducing the concepts of critical concentration and coefficient of consumption activity. General equations for microbial cell concentration for continuous cultivation in continuous-stirred tank and tubular type reactors were derived theoretically. Productivity of cell mass in continuous cultivation was analyzed kinetically and the behavior of mutant populations in continuous cultivation is briefly discussed.