Adhesion of Lactobacillus plantarum 423 and Lactobacillus salivarius 241 to the intestinal tract of piglets, as recorded with fluorescent in situ hybridization (FISH), and production of plantaricin 423 by cells colonized to the ileum

Aims: To determine which intestinal section of pre and postweaned piglets are colonized by Lactobacillus plantarum 423 and Lactobacillus salivarius 241, and follow production of plantaricin 423 in a gastro-intestinal model. Methods and Results: Lactobacillus plantarum 423 and Lact. salivarius 241, single or in combination, were administered to 1-, 14- and 28-day-old (postweaned) piglets. According to results obtained by fluorescent in situ hybridization (FISH), Lact. plantarum 423 adhered strongly to the ileum and posterior colon and Lact. salivarius 241 to the duodenum in preweaned piglets. High numbers of strain 241 were recorded in the duodenum and posterior colon of postweaned piglets, whereas strain 423 remained localized to the ileum. Lowering in Enterococcus faecalis cell numbers were recorded when preweaned piglets were challenged with strain 241. Plantaricin 423 was produced for 96 h in the ileum section of a gastro-intestinal model. Conclusions: Lactobacillus plantarum 423 and Lact. salivarius 241 adhere to different sections of the intestinal tract, depending on the piglet's age. Ent. faecalis were inhibited in vivo, probably by plantaricin 423. Significance and Impact of the Study: Fluorescent in situ hybridization proved valuable in the detection of probiotic bacteria adhered to the intestine. This is the first report of bacteriocin production in a model simulating the porcine gastro-intestinal tract. © 2006 The Society for Applied Microbiology.Articl

Degradation of humic acids in a microbial film consortium from landfill compost

Bacterial biofilms are ubiquitous in nature and industrial settings. In this study, a biofilm consortium was enriched in a continuous-flow-cell system using humic acid as the sole carbon and energy source. The degradation of the humic acids by the consortium under two supplementary carbon sources was investigated by ultraviolet (UV) absorbency, Fourier transform infrared (FTIR) spectroscopy, and electrospray mass spectrometry (ES-MS). The morphological characteristics of the biofilm consortium and the isolated cultures from the biofilm were observed under an epifluorescence microscope. The metabolic diversity of the selected cultures from the degradative consortium, based on substrate usage pattern, was examined using Biolog EcoPlates. Microscopic analysis revealed that the biofilm was formed by various morphotypes of bacteria, fungi, and yeasts, as well as amoebas. The substrate usage profiles of the bacteria confirmed that, in addition to yeasts and fungi, two groups of bacterial consortia were developed in the biofilm to degrade the humic acids. The degradation of humic acid in the biofilm was mostly carried out in a secondary or a cometabolic path. Addition of the readily digestible external carbon source enhanced the growth of the biofilm consortium. The FTIR and ES-MS spectra confirmed the changes in chemical structure of the humic acid by the biofilm community.Articl

Methanogenic digestion of lignocellulose residues under conditions of high-rate acidogenic fermentation

A semicontinuous module reactor was operated under methanophilic conditions to effect rapid solid anaerobic digestion of lignocellulose substances for waste utilization and stabilization. This was achieved by recovering the methanogenic phase from the high-rate acidogenic fermentation phase. The influence of a total carbon to nitrate ratio (C/N(NO3)) of the lignocellulose feed on the development of methanogens from a high-rate acidification fermentation phase was first investigated. The effects of Ph adjustment and dilution of the high-rate acidification fermentation phase using the two-phase anaerobic digestion configuration were subsequently evaluated. The results showed that an increase in the C/N(NO3) ratio of the feed substrate could promote the development of methanogens as a result of the restraint of denitrification during or after the acidification fermentation phase. In-process neutralization of the digestion pH and dilution of the digestion intermediate products could reduce the inhibition from the high-rate acidification fermentation phase. The integrated digestion process promoted the biotransformation of lignocellulose residues from the high-rate acidification phase to the methanogenic phase and ultimately stabilized digestion.Articl

Degradation of humic acids in a microbial film consortium from landfill compost

Bacterial biofilms are ubiquitous in nature and industrial settings. In this study, a biofilm consortium was enriched in a continuous-flow-cell system using humic acid as the sole carbon and energy source. The degradation of the humic acids by the consortium under two supplementary carbon sources was investigated by ultraviolet (UV) absorbency, Fourier transform infrared (FTIR) spectroscopy, and electrospray mass spectrometry (ES-MS). The morphological characteristics of the biofilm consortium and the isolated cultures from the biofilm were observed under an epifluorescence microscope. The metabolic diversity of the selected cultures from the degradative consortium, based on substrate usage pattern, was examined using Biolog EcoPlates. Microscopic analysis revealed that the biofilm was formed by various morphotypes of bacteria, fungi, and yeasts, as well as amoebas. The substrate usage profiles of the bacteria confirmed that, in addition to yeasts and fungi, two groups of bacterial consortia were developed in the biofilm to degrade the humic acids. The degradation of humic acid in the biofilm was mostly carried out in a secondary or a cometabolic path. Addition of the readily digestible external carbon source enhanced the growth of the biofilm consortium. The FTIR and ES-MS spectra confirmed the changes in chemical structure of the humic acid by the biofilm community.Articl

Dynamics of a microbial biofilm in a rotating biological contactor for the treatment of winery effluent

Wastewater from wine-related industries is characterised by high variability in COD and pH. Disposal of these effluents with little or no treatment could lead to heavy financial penalties or pollution of soil and water resources. A pilot-scale rotating biological contactor (RBC) was evaluated for the treatment of winery effluent, with specific focus on the biofilms that formed on the RBC discs. On average, the RBC reduced the influent COD of the winery effluent by 23% (from 3 828 mg/ℓ to 2 910 mg/ℓ) and increased the pH by 0.95 units (from 5.77 to 6.13) at an average retention time of 1h. Similar results were obtained during evaluations at a wine-bottling plant where thick active biofilms, containing mostly yeasts, formed on the discs and proved stable and resilient to various physical and chemical shocks.Articl

Response of the microbial community to copper oxychloride in acidic sandy loam soil

Aims: Determining the response of different microbial parameters to copper oxychloride in acidic sandy loam soil samples using cultivation-dependent and direct microscopic techniques. Methods and Results: Culturable microbial populations were monitored for 245 days in a series of soil microcosms spiked with different copper oxychloride concentrations. Microbial populations responded differently to additional Cu. Protistan numbers and soil metabolic potential decreased. Experiments with more soil samples revealed that metabolic potential was not significantly affected by ≤100 mg kg-1 additional Cu. However, a negative impact on protista was noted in soil containing only 15 mg kg-1 EDTA-extractable Cu. The negative impact on protistan numbers was less severe in soils with a higher phosphorous and zinc content. Conclusions: Bacterial populations responded differently, and protista were most sensitive to elevated Cu levels. Protistan numbers in soil from uncultivated land were higher and seemed to be more sensitive to additional Cu than the numbers of these organisms in soil originating from cultivated land. Significance and Impact of the Study: Protistan sensitivity to small increases in Cu levels demonstrates the vulnerability of the soil ecosystem to Cu perturbations, especially when the importance of protista as link in the flow of energy between trophic levels is considered. © 2005 The Society for Applied Microbiology.Articl