A Continuous Culture System for Assessing Microbial Activities in the Piezosphere

Continuous culture under elevated pressures is an important technique for expanding the exploration of microbial growth and survival in extreme environments associated with the deep biosphere. Here we present a benchtop stirred continuous culture bioreactor capable of withstanding temperatures ranging from 25 to 120°C and pressures as high as 69 MPa. The system is configured to allow the employment of media enriched in dissolved gases, under oxic or anoxic conditions, while permitting periodic sampling of the incubated organisms with minimal physical/chemical disturbance inside the reactor. In a pilot experiment, the fermentative growth of the thermopiezophilic bacterium Marinitoga piezophila was investigated continuously for 382 h at 65°C and at pressures ranging from 0.1 to 40 MPa while the medium flow rate was varied from 2 to 0.025 ml/min. The enhanced growth observed at 30 and 40 MPa and 0.025 ml/min supports the pressure preferences of M. piezophila when grown fermentatively. This assay successfully demonstrates the capabilities of the bioreactor for continuous culturing at a variety of dilution rates, pressures, and temperatures. We anticipate that this technology will accelerate our understanding of the physiological and metabolic status of microorganisms under temperature, pressure, and energy regimes resembling those of the Earth''s piezosphere.     

A Continuous Culture Device for Protozoan Cells

SYNOPSIS. A continuous culture device suitable for controlled growth of Euglna gracilis is described. It could probably be adapted to other similar cell types with generation times no greater than 150–200 hrs.     

快速、无损大豆种子连续取样技术及其DNA制备

建立简便、快速和无损种子连续取样技术流程及基因型鉴定技术体系,可节约种植成本及缩短鉴定周期,提高基因功能研究和育种效率。该研究利用微型电钻和空气泵等简单装置设计了一种连续且无损钻取大豆(Glycine max)种子组织的方法,并优化了利用384深孔微孔板高通量提取DNA及基因型鉴定技术体系。该方法也可用于水稻(Oryz...     

Predicting Production in Light-Limited Continuous Cultures of Algae

Equations relating productivity, growth rate, cell concentration, and light absorption lead to the prediction that, when incident light is below saturating intensity, maximal productivity will occur at half the maximal growth rate. The freshwater alga Chlorella pyrenoidosa TX71105 and the marine alga Dunaliella tertiolecta were grown in a small continuous culture apparatus with turbidostatic control. With both cultures, the cell concentration showed a linear decrease with dilution rate. Productivity was maximal at about one-half the maximal dilution rate. Average mass per cell increased near the maximal dilution rate, causing some asymmetry in the productivity versus dilution rate curve. The chlorophyll content per unit mass decreased in this region, but the chlorophyll content per cell remained constant. Best production rate in a light-limited algal culture was obtained when the growth rate at very low cell concentration was determined in the apparatus and the dilution rate was set at one-half that value.     

Continuous Culture Used for Media Optimization

A technique is described in which continuous culture is used for the optimization of media in terms of growth-supporting ability. The technique consists of identifying growth-limiting nutrients by observing the reaction of the continuous system to injection of suspected growth-limiting nutrients into the growth vessel.     

A System for the Quantitative Sampling of Shallow Water Benthos

An air lift, operated by a diver-boatman team and permitting rapid excision and automatic sieving of uniform portions of mud, sand, and fine to medium shell hash bottoms, is described. The apparatus can be deployed from a very small boat. It is inexpensive to make and to operate and has been used with great success at depths of not more than five meters.     

Methods for Growing Tintinnida in Continuous Culture

A continuous—flow culturing apparatus was developed forrearing Tintinnida. Control over the yield of protozoa is throughadjustment of both the food input and the flow rate. The maximumsustained output of Tintinnopsis beroidea approached 10³ cells/ml,and higher yields are believed possible. The advantages of theapparatus for ecological investigations, and the required modificationsfor analysis of tintinnid trophodynamics, are discussed.     

Electronically Controlled Continuous Culture Device

A photocell-controlled continuous culture device, a Nephelostat, is described that maintains a wide variety of cultures of microorganisms in balanced growth. This Nephelostat controls concentrations of bacteria within +/-3% over a cell concentration range of 10(6) to 10(9) cells per ml. Growth rates are recorded so that changes in the growth rate are observed over small increments of time. Spontaneous and caffeine-induced mutation rates of two strains of Escherichia coli were compared under Nephelostat and chemostat conditions.     

Cyanobacteria-cyanophage Interactions in Continuous Culture

When the filamentous Plectonema boryanum 594 or the unicellular Aphanothece stagnina were grown in chemostats with phages LPP-DUN1 and Aph-1, respectively, an initial series of reciprocal oscillations in cyanobacterial and phage numbers occurred; their magnitudes decreased successively until an equilibrium population of cyanobacteria and virus was established in each system. Evolution of the protagonists occurred as the interactions proceeded. Most of the A. stagnina population appeared resistant to Aph-1 at the end of the experiment. Two types of resistant P. boryanum , designated PR1 and PR2, were isolated. PR1 was resistant to wild-type LPP-DUN1 but susceptible to a mutant phage; PR2 was unaffected by the phage. The sequence of appearance and interaction of mutant phage and P. boryanum accounted for the initial fluctuations in population numbers, and the coexistence of host and pathogen in the climax population. Plectonema boryanum PR2 grew more slowly than wild-type, or PR1 and competed poorly with them in the absence of phage. The ecological implications of the results are discussed.     

Accounting for Algae

Interest and research in the use of algae for energy is growing but an analysis of the different methods for the accounting for the carbon dioxide (CO ₂) emissions that result, is lacking. In this article, four accounting systems are evaluated for their completeness, simplicity, sectoral accuracy, and scale‐independence. Two options under the Kyoto Protocol (KP), a value‐chain (end‐user responsibility) approach, and Point of Uptake and Release (POUR) are evaluated. Algal material is used in biofuels, animal feeds, human foods, and food supplements, and a range of products such as paints, cosmetics, and plastics. There are also proposals for using algae as a soil amendment. This variety of uses for algal material together with the fact that it will probably contain carbon of fossil origin presents accounting challenges and reveals inconsistencies that have lain in the KPs treatment of biomass emissions. Furthermore, a key conclusion of the article is that neither proposed KP accounting approach for algae leads to correct accounting of emissions for all uses. Both value chain and POUR approaches more correctly and consistently account for algal emissions across uses. POUR offers the potential to provide comprehensive, consistent emission accounting across all uses of biomass, which represents a major step forward in accounting for CO ₂ emissions due to use of biomass.     

Excretion of Ribitol and Sucrose by Green Algae into the Culture Medium

Among 8 strains of algae grown with C¹⁴O₂ as a sole source of carbon, two species of Trebouxia produced appreciable amounts of two photosynthetic products in the culture medium. One of them was identified as sucrose by cochromatography and by acid hydrolysis. The other compound was identified as ribitol by paper chromatography, paper electrophoresis, periodic acid oxidation, recrystallization with authentic ribitol and finally by the enzymatic method with ribitol dehydrogenase.     

Yield Constant for Acanthamoeba polyphaga in Batch and Continuous Culture1

ABSTRACT. A two-stage chemostat modified to accommodate the growth of adhesive organisms was used to determine the yield constant, Y, of a representative soil amoeba, Acanthamoeba polyphaga, utilizing as its prey Pseudomonas paucimobilis. The first stage consisted of a glucose-limited bacterial culture in steady state. The second stage consisted of a simplified predator-prey system, nongrowing bacteria serving as the limiting substrate for amoebae. A refined methodology to more accurately determine Y was developed, and Y for Acanthamoeba polyphaga in batch and continuous culture was determined to be 19.1%.