Continuous cultivation of the lithoautotrophic nitrate-reducing Fe(II)-oxidizing culture KS in a chemostat bioreactor

Laboratory-based studies on microbial Fe(II) oxidation are commonly performed over just a few weeks in small volumes with high substrate concentrations, resulting in geochemical gradients and volumetric effects caused by sampling. We used a chemostat to enable uninterrupted supply of medium, and investigated autotrophic growth of the nitrate-reducing Fe(II)-oxidizing culture KS for 24 days. We analysed Fe- and N-speciation, cell-mineral associations, and the identity of minerals. Results were compared to different batch systems (50 and 700 ml – static/shaken). The Fe(II) oxidation rate was highest in the chemostat with 7.57 mM Fe(II) d-1, while the extent was similar (averaged 92% of all Fe(II)). Short-range ordered Fe(III) phases, presumably ferrihydrite, precipitated and later goethite was detected in the chemostat. 1 mM solid phase Fe(II) remained in the chemostat, up to 15 µM of reactive nitrite was measured, and 42% of visualized cells were partially or completely mineral-encrusted, likely caused by abiotic oxidation of Fe(II) by nitrite. Despite (partial) encrustation, cells were still viable. Our results show that even with similar oxidation rates as in batch cultures, cultivating Fe(II)-oxidizing microorganisms under continuous conditions reveals mechanistic insights on the role of reactive intermediates for Fe(II) oxidation, mineral formation and cell-mineral interactions.

The history, etiology, and management of ginseng replant disease: a Canadian perspective in review

Ginseng replant disease (GRD) has had a major impact on the American ginseng (Panax quinquefolius L.) industry in Canada and is a threat to its survival. With only 150 yr of domestic ginseng cultivation, GRD and its effect on the industry in North America is well documented compared with replant diseases in other crops. However, minimal research has been published on the etiology and management of GRD. Research and observations of replant diseases of the major commercial Panax species worldwide are presented to propose mechanisms of GRD and potential management options. The available evidence suggests the specific involvement of the soil-borne fungus Ilyonectria mors-panacis (A.A. Hildebr.) A. Cabral & Crous combined with an unknown host-related factor as the ultimate cause of GRD, since other proposed mechanisms seem unlikely to have occurred in the diversity of regions where GRD is reported. Other abiotic and biotic factors influencing the severity of the disease are also likely to be involved. Given the lack of clarity in the scientific literature between problems associated with continuous cultivation of ginseng and true replant disease, a definition of GRD is proposed. The development of an effective and economical management regime will require a better understanding of the mechanisms of GRD. Potential management options include reducing ginseng debris after harvest of the first crop, preplant testing to identify low-risk sites for replanting, fumigation, alternative disinfestation techniques, and fungicides (including biofungicides) targeting I. mors-panacis.

Potential Impact of Climate Change on Six Economically Important Horticultural Crops in West Africa

Colocasia esculenta (taro), Ipomoea batatas (sweet potato), Abelmoschus esculentus (okra), Ananas cosmosus (pineapple), Musa paradisiaca (plantain), and Anacardium occidentale (cashew) are economically important horticultural crops in West Africa, which are widely grown across the region under rain fed conditions. They are very important set of crops that provides income for the individuals involved with it and thus contributing to economy of West African nation’s. For Predicting the potential future habitat suitability of these crops under different climate scenarios holds significance for their continuous cultivation and effective management. The Maxent model was used in this study to predict habitat suitability of these crops under current and future climatic conditions based on two representative concentration pathways (RCP4.5 and RCP8.5) for the years 2050s and 2070s. The data used were the occurrence records from Global Biodiversity Information Facility (GBIF) and WorldClim’s bioclimatic environmental predictor variables. The findings of this experiment showed that the habitat suitability of some crop species will =decrease and in some it will increase. Suitable habitat was predicted to decrease within the semi-arid and arid areas of the region, especially on those countries in northern part which includes Niger, Mali and Burkina Faso, as early as by 2070s. For species like okra, sweet potato and taro, there will be further decline as predicted under the higher emission scenario of RCP 8.5. The suitable habitat for cashew remained stable for future in all the models and scenarios used. This work provides the first theoretical guidance for possible future cultivation of these horticultural crops in the West Africa.

Determining the energy efficiency of an agrorobot

The problem of feeding the population and the lack of trained staff for growing crops is increasing all over the world. This inevitably leads to a change in technology for growing crops. These new technologies rely on autonomous robotic systems for the continuous cultivation of crops without human personnel. Robots are small, smart, interconnected, lightweight machines that aim to release the person from the basic everyday pursuits. Globally, there is a trend in agriculture to automate the hard manual labor with continued increases in yields to feed the population. This article discusses the problems of determining the main energy aspects of agricultural robots. Guidelines are given for determining the energy saving of the robot, depending on the time for its long autonomous operation, the terrain to be cultivated and a number of other factors. Exemplary values of the energy required to drive the agricultural robot and the time for energy recovery through renewable energy sources have been determined.

Dynamic development of the winery sector in Greece

Виноградарство в Греции - старейшая отрасль, но в последние годы наблюдается сокращение площадей, предназначенных для производства винодельческой продукции. Производство и маркетинг вина - сильная промышленность в мировой экономике. Международный и внутренний рынки стандартизированных вин считаются высоко конкурентными и комплексными. История греческого вина охватывает чрезвычайно долгий период, самый продолжительный в мире с точки зрения непрерывного выращивания винограда и производства вин с незапамятных времен. Виноделие - один из важнейших секторов греческой экономики не только для внутреннего рынка напитков, но и для развития и продвижения традиционных греческих продуктов за рубежом в целом. В винодельческой отрасли в последние годы произошли структурные изменения, направленные на повышение конкурентоспособности греческих вин для занятия ими достойного места на международном рынке. В последние пять лет среди греческих винных компаний стали появляться тенденции к международной экстраверсии. Греция по производству вина занимает 12-е место в мире и 4-е в Европейском Союзе. В этой работе делается попытка составить карту «маршрута» вина с его разновидностями и объемами производства по всей Греции. Viticulture in Greece is the oldest, but in recent years there has been a reduction of areas intended for wine production. Wine production and marketing is a strong industry worldwide. The global and domestic market for standardized wine is considered to be complex and highly competitive. The history of Greek wine covers an extremely long period of time, the longest in the world, in terms of continuous cultivation of the vine and the timeless production of wines. The wine industry is one of the most important sectors of Greek economy not only for the domestic beverage market, but also for the development and promotion of Greek traditional products in general in foreign markets. In wine industry, structural changes have taken place in recent years aimed to increase the competitiveness of Greek wines, in order to gain a worthy position in the international market. Last five years, there has been a trend for international extroversion by Greek wine companies. Greece with wine production occupies 12 place in the world and 4 in the European Union. This work attempts to map the "route" of wine with its varieties and production quantities throughout Greece.

Real-Time Monitoring of Microalgal Biomass in Pilot-Scale Photobioreactors Using Nephelometry

The increasing cultivation of microalgae in photobioreactors warrants efficient and non-invasive methods to quantify biomass density in real time. Nephelometric turbidity assessment, a method that measures light scatter by particles in suspension, was introduced already several decades ago but was only recently validated as a high-throughput tool to monitor microalgae biomass. The light scatter depends on the density of the suspended particles as well as on their physical properties, but so far there are hardly any accounts on how nephelometric assessment relates to classic methods such as dry weight and spectrophotometric measurement across a broad biomass density range for different microalgae species. Here, we monitored biomass density online and in real time during the semi-continuous cultivation of three commercial microalgae species Chloromonas typhlos, Microchloropsis gaditana and Porphyridium purpureum in pilot-scale photobioreactors, and relate nephelometric turbidity to dry weight and optical density. The results confirm a relatively strong (R2 = 0.87–0.93) and nonlinear relationship between turbidity and biomass density that differs among the three species. Overall, we demonstrate how nephelometry can be used to monitor microalgal biomass in photobioreactors, and provide the necessary means to estimate the biomass density of the studied species from turbidity data to facilitate automated biomass monitoring.

Effects of Process Variables in Semi-continuous Cultivation of Chlorella Minutissima on the Biomass Composition

The biomass composition of Chlorella minutissima 26a was evaluated in different conditions for the microalgae cultured in landfill leachate in airlift photobioreactor operated in semi-continuous mode. The effects of the following factors in cells composition were evaluated: landfill leachate concentration (LC), CO2 percentual flow added in the gas stream (GP), aeration flow in the reactor (AF) and feed flowrate (FR). A Taguchi L9 orthogonal arrangement was used to evaluate the effects of those four factors on the following response variables: Biomass Productivity (BP), Lipid Productivity (LP), Carbohydrate Productivity (CP) and Proteins Productivity (PP). Results showed that the microalgae had high selectivity to produce proteins, reaching a maximum content of 69,60% in the following conditions: LC: 10%, GP: null, AF: 0,30 vvm and FR: 0.9 µmax vvm. The highest contents of lipid and carbohydrate were 17.4% (LC: 15%, GP: null, AF: 0,45 vvm and FR: 0.7 µmax vvm) and 11.6% (LC: 10%, GP: 15%, AF: 0,15 vvm and FR: 0.7 µmax vvm.), respectively, both values achieved at the two experiment with the highest values of specific growth rate (0.44 d-1 and 0.47 d-1, respectively). Statistical analysis showed LC was the most influential factor in the cell chemical composition, being significant (p<0,1) in the productivity of lipids, proteins and carbohydrates, with high values observed using between 5 and 10% of LC in the medium. GP did not show significance for any response studied, while the variables AF and FR showed significance in the productivity of proteins.