Communications in agricultural and applied biological sciences 

About: Communications in agricultural and applied biological sciences is an academic journal. The journal publishes majorly in the area(s): Population & Weed. It has an ISSN identifier of 1379-1176. Over the lifetime, 1554 publications have been published receiving 8116 citations.

The anode potential regulates the bacterial activity in microbial fuel cells.

Abstract: The anode potential in microbial fuel cells controls both the theoretical energy gain for the microorganisms as the output of electrical energy. We operated three reactors fed with acetate continuously at a poised anode potential of 0 (R0), −200 (R−200) and −400 (R−400) mV versus Ag/AgCl and investigated the resulting bacterial activity. The anode potential had no influence on the start-up time of the three reactors. During a 31-day period, R−200 produced 15% more charge compared to R0 and R−400. In addition, R−200 had the highest maximal power density (up to 199 W m−3 total anode compartment during polarization) but the three reactors evolved to the same power density at the end of the experimental period. During polarization, only the current of R−400 levelled off at an anode potential of −300 mV versus Ag/AgCl. The maximum respiration rate of the bacteria during batch tests was also considerably lower for R−400. The specific biomass activity however, was the highest for R−400 (6.93 g chemical oxygen demand g−1 biomass-volatile suspended solids (VSS) d−1 on day 14). This lowered during the course of the experiment due to an increase of the biomass concentration to an average level of 578 ± 106 mg biomass-VSS L−1 graphite granules for the three reactors. This research indicated that an optimal anode potential of −200 mV versus Ag/AgCl exists, regulating the activity and growth of bacteria to sustain an enhanced current and power generation.

No evidence of a plant extinction debt in highly fragmented calcareous grassland in Belgium.

Abstract: ARTICLE INFOArticle history:Received 9 March 2006Received in revised form6 June 2006Accepted 9 June 2006Available online 14 August 2006Keywords:Plant species richnessLand-use historyConnectivityHabitat areaLife-history traitsEmergent groupsABSTRACTLong transient times in response to decreasing habitat area and increasing isolation maycause the present plant species distribution to reflect the historical rather than the presentlandscape configuration, resulting in a so-called extinction debt. To investigate how plantspecies richness is shaped by both present and historical landscape configuration and localenvironmental conditions in fragmented calcareous grasslands, 64 sites in Southern Bel-gium were surveyedfor their total species richness and environmental characteristics. Spe-cies were subdivided in specialist and generalist groups and the former were clustered intoemergent groups (EGs) according to 16 relevant life-history traits. Four specialist emergentgroups were derived: orchids, rosette species, annuals and half-rosette species. Both spe-cialist and generalist species richness increased with present fragment area, while presentfragment connectivity only affected the number of specialist species. This trend was main-tained for most EGs, although habitat area was mostly more important than connectivity.All species groups responded to an insolation gradient, except EGs of rosette and annualspecies. Differential response to fragmentation among emergent groups could be inter-preted in terms of dispersal and persistence traits. No relation between species richnessand historical area or connectivity was found, making an extinction debt unlikely. Hence,present-day variation in plant species diversity seems to be no legacy of past landscapeconfiguration. Our results clearly indicate that plant species may be quickly lost inresponse to new fragmentation events. To restore plant diversity, management shouldfocus both on mitigating landscape fragmentation and restoring habitat quality. 2006 Elsevier Ltd. All rights reserved.

Effect of high pressure/high temperature processing on cell wall pectic substances in relation to firmness of carrot tissue.

Abstract: Thermal processing for food preservation results in undesired softening of fruits and vegetables. To explore the potential of high pressure sterilization in food processing, the effects of combined high pressure/high temperature (HP/HT) treatments on carrot pectic polysaccharides and the related textural properties were investigated and compared with that of samples thermally processed at atmospheric pressure. Disks of fresh carrot (Daucus carota var. Yukon) tissue were subjected to three different treatments (80 C–0.1 MPa, 100 C– 0.1 MPa and 80 C–600 MPa) for varying time intervals. Subsequently, the residual texture and microstructural changes of the carrots were evaluated. Alcohol-insoluble residues were prepared from the samples and sequentially fractionated with water, cyclohexane-trans1,2-diamine tetra-acetic acid (CDTA) and Na2CO3 solutions. Thermal treatments at 0.1 MPa caused extensive tissue softening. This was marked by increased cell separation, an increase in water soluble pectin (WSP) paralleled by a decrease in chelator (CSP) and sodium carbonate (NSP) soluble pectin. HP/HT treated carrots showed minimal softening and negligible changes in intercellular adhesion. This was accompanied by a significant reduction in the degree of methyl esterification of pectin, low WSP in contrast to the high CSP and NSP fractions, minor changes in the different pectin fractions during treatment, and a substantial amount of pectin in the fractionation residue. There was a clear difference between HP/HT and thermally processed carrot pectin; HP/HT showing pronounced texture preservation. 2007 Elsevier Ltd. All rights reserved.

Mild-Heat and High-Pressure Inactivation of Carrot Pectin Methylesterase: A Kinetic Study

Abstract: Pectin methylesterase (PME) was extracted from carrots and purified by affinity chromatography. The thermal high-pressure inactivation of the PME was investigated in a model system. Under these conditions, the (thermo) stable fraction is not inactivated and the isobaric-isothermal inactivation followed a fractional-conver- sion model. At lower pressures ( 50 °C), an antagonistic effect of pres- sure and heat was observed. A 2nd- and 3rd-degree polynomial model (derived from available thermodynamic model) was successfully used to describe the heat pressure dependence of the inactivation rate constants. From the purified carrot PME sample, the thermostable PME fraction was isolated. The thermal inactivation of this fraction followed first-order kinetics.