Diversity of lactic acid bacteria of the bioethanol process

<p>Abstract</p> <p>Background</p> <p>Bacteria may compete with yeast for nutrients during bioethanol production process, potentially causing economic losses. This is the first study aiming at the quantification and identification of Lactic Acid Bacteria (LAB) present in the bioethanol industrial processes in different distilleries of Brazil.</p> <p>Results</p> <p>A total of 489 LAB isolates were obtained from four distilleries in 2007 and 2008. The abundance of LAB in the fermentation tanks varied between 6.0 × 10⁵and 8.9 × 10⁸CFUs/mL. Crude sugar cane juice contained 7.4 × 10⁷to 6.0 × 10⁸LAB CFUs. Most of the LAB isolates belonged to the genus <it>Lactobacillus </it>according to rRNA operon enzyme restriction profiles. A variety of <it>Lactobacillus </it>species occurred throughout the bioethanol process, but the most frequently found species towards the end of the harvest season were <it>L. fermentum </it>and <it>L. vini</it>. The different rep-PCR patterns indicate the co-occurrence of distinct populations of the species <it>L. fermentum </it>and <it>L. vini</it>, suggesting a great intraspecific diversity. Representative isolates of both species had the ability to grow in medium containing up to 10% ethanol, suggesting selection of ethanol tolerant bacteria throughout the process.</p> <p>Conclusions</p> <p>This study served as a first survey of the LAB diversity in the bioethanol process in Brazil. The abundance and diversity of LAB suggest that they have a significant impact in the bioethanol process.</p

Application of molecular biological methods for studying probiotics and the gut flora

Increasingly, the microbiological scientific community is relying on molecular biology to define the complexity of the gut flora and to distinguish one organism from the next. This is particularly pertinent in the field of probiotics, and probiotic therapy, where identifying probiotics from the commensal flora is often warranted. Current techniques, including genetic fingerprinting, gene sequencing, oligonucleotide probes and specific primer selection, discriminate closely related bacteria with varying degrees of success. Additional molecular methods being employed to determine the constituents of complex microbiota in this area of research are community analysis, denaturing gradient gel electrophoresis (DGGE)/temperature gradient gel electrophoresis (TGGE), fluorescent in situ hybridisation (FISH) and probe grids. Certain approaches enable specific aetiological agents to be monitored, whereas others allow the effects of dietary intervention on bacterial populations to be studied. Other approaches demonstrate diversity, but may not always enable quantification of the population. At the heart of current molecular methods is sequence information gathered from culturable organisms. However, the diversity and novelty identified when applying these methods to the gut microflora demonstrates how little is known about this ecosystem. Of greater concern is the inherent bias associated with some molecular methods. As we understand more of the complexity and dynamics of this diverse microbiota we will be in a position to develop more robust molecular-based technologies to examine it. In addition to identification of the microbiota and discrimination of probiotic strains from commensal organisms, the future of molecular biology in the field of probiotics and the gut flora will, no doubt, stretch to investigations of functionality and activity of the microflora, and/or specific fractions. The quest will be to demonstrate the roles of probiotic strains in vivo and not simply their presence or absence

Comparison of the faecal microflora of patients with ankylosing spondylitis and controls using molecular methods of analysis

Objectives. To determine whether differences within the complex intestinal microflora can be demonstrated between patients with ankylosing spondylitis (AS) and healthy individuals. Methods. The composition of the faecal microflora of 15 ankylosing spondylitis patients and 15 matched controls was determined using a variety of nucleic acid-based methods, including denaturing gradient gel electrophoresis (DGGE). Concentrations of serum antibodies reactive with intestinal bacteria were determined. T-cell proliferation responses to autologous intestinal bacteria were determined using a bioluminescent assay. Results. DGGE demonstrated a unique and stable bacterial community in the faeces of each individual. No specific differences in colonization profiles were discernible between patients and controls. Analysis of individual bacterial groups using nucleic acid-based methods showed no differences in faecal colonization with Klebsiella pneumoniae or Bacteroides vulgatus. A significantly higher proportion of faecal samples from AS patients were found to contain sulphate-reducing bacteria compared with samples from controls (P=0.0004). Three out of five patients showed elevated T-cell proliferation responses to Bacteroides species cultured from their own faeces. The concentrations of serum immunoglobulin A (IgA) and IgM antibodies reactive with klebsiella or bacteroides cells were lower in the patient group relative to the controls. Conclusions. By using DGGE, we have demonstrated the complexity and individuality of the human intestinal microflora and shown that this is a confounding factor in determining the possible significance of individual organisms in the pathogenesis of spondyloarthritis. Nevertheless, we demonstrated a higher prevalence of sulphate-reducing bacteria in the faeces of patients with AS. These organisms have been implicated in the pathogenesis of inflammatory bowel disease. We also detected a possible loss of immunological tolerance to autologous Bacteroides isolates in patients with AS