Mogens Jakobsen

Gut Microbiota in Human Adults with Type 2 Diabetes Differs from Non-Diabetic Adults

Background Recent evidence suggests that there is a link between metabolic diseases and bacterial populations in the gut. The aim of this study was to assess the differences between the composition of the intestinal microbiota in humans with type 2 diabetes and non-diabetic persons as control. Methods and Findings The study included 36 male adults with a broad range of age and body-mass indices (BMIs), among which 18 subjects were diagnosed with diabetes type 2. The fecal bacterial composition was investigated by real-time quantitative PCR (qPCR) and in a subgroup of subjects (N = 20) by tag-encoded amplicon pyrosequencing of the V4 region of the 16S rRNA gene. The proportions of phylum Firmicutes and class Clostridia were significantly reduced in the diabetic group compared to the control group (P = 0.03). Furthermore, the ratios of Bacteroidetes to Firmicutes as well as the ratios of Bacteroides-Prevotella group to C. coccoides-E. rectale group correlated positively and significantly with plasma glucose concentration (P = 0.04) but not with BMIs. Similarly, class Betaproteobacteria was highly enriched in diabetic compared to non-diabetic persons (P = 0.02) and positively correlated with plasma glucose (P = 0.04). Conclusions The results of this study indicate that type 2 diabetes in humans is associated with compositional changes in intestinal microbiota. The level of glucose tolerance should be considered when linking microbiota with metabolic diseases such as obesity and developing strategies to control metabolic diseases by modifying the gut microbiota.

Yeasts and their possible beneficial and negative effects on the quality of dairy products

Abstract This review deals with yeasts and their potential use as starter cultures in dairy products as well as their role as spoilage organisms. The taxonomy of relevant yeasts is described, with emphasis on molecular techniques and simplified identification systems applicable to industry. Quantitative assessment of undesirable yeast contamination is discussed with regard to present requirements for quality assurance in dairies. Special attention is given to the role of yeasts in the complex microbial interactions prevailing in several dairy products and to controlling fermentation, maturation and important product characteristics. Antimicrobial activities of yeasts, including secretion of ‘killer factors’ with broad antimicrobial spectra are linked with the reported probiotic starter cultures. The desired properties of yeasts to be used as starter cultures in the dairy industry are summarized and areas of research are proposed to gain the insight required to obtain full advantage of the active use of yeast cultures in a wider range of products.

Effect of probiotic Lactobacillus strains in young children hospitalized with acute diarrhea.

Background. Oral bacteriotherapy promotes recovery from acute childhood diarrhea, but few strains have been shown to have therapeutic potentials. We examined the effect of two newly identified probiotic Lactobacillus strains in acute childhood diarrhea. Methods. Sixty-nine children were randomized during hospitalization for acute diarrhea to receive a mixture of Lactobacillus rhamnosus 19070-2 and Lactobacillus reuteri DSM 12246, 1010 colony-forming units of each strain or placebo twice daily for 5 days. Before selection of these stains their potential probiotic characteristics were demonstrated in vitro and in healthy volunteers. Results. In patients receiving probiotics, the diarrheal phase was reduced by 20%. The duration of diarrhea was 82 h in the treatment group vs. 101 h in the control group (not significant, P = 0.07). However, 3 of 30 patients from the treatment group vs. 13 of 39 from the control group still had loose stools at the end of the study period (P = 0.03). In patients with diarrhea for <60 h before start of treatment (early intervention), a clear effect of the probiotics was demonstrated (80 h in the treatment group vs. 130 h in the control group, P = 0.003). After early intervention, the length of hospitalization was reduced by 48% (3.5 vs. 1.7 days, P = 0.03). At the end of the intervention, rotavirus antigen was found in 12% of patients from the treatment group vs. 46% from the control group (P = 0.02). Conclusions. The two probiotics, L. rhamnosus 19070-2 and L. reuteri DSM 12246, ameliorated acute diarrhea in hospitalized children and reduced the period of rotavirus excretion. Oral bacteriotherapy was associated with a reduced length of hospital stay. The beneficial effects were most prominent in children treated early in the diarrheal phase.

Specific spoilage organisms in breweries and laboratory media for their detection

The Gram positive bacteria are generally regarded as the most hazardous beer spoilage organisms in modern breweries, especially the lactobacilli: L. brevis, L. lindneri, L. curvatus, L. casei, L. buchneri, L. coryneformis, L. plantarum, L. brevisimilis, L. malefermentans and L. parabuchneri and the pediococci: P damnosus, P. inopinatus and P. dextrinicus. Micrococcus kristinae is the only species within the micrococci relevant to brewing. The Gram negative strictly anaerobic bacteria are apparently increasing in importance and include Pectinatus cerevisiiphilus, Pectinatus frisingensis and Selenomonas lacticifex, reported as obligate beer spoilage organisms: Zymophilus raffinosivorans as a potential beer spoilage organism; Megasphaera cerevisiae as an obligate spoilage organism of low alcohol beer and Zymomonas mobilis as capable of spoiling primed beer. With improved process technology the importance of aerobic bacteria has decreased and the same applies for the Gram negative aerobic bacteria Hafnia protea and Enterobacter cloacae which are capable of surviving beer fermentation. Beer spoilage organisms include several so-called wild yeasts, of which Saccharomyces species are generally considered the most important. Even though the detection of beer spoilage organisms by cultivation in laboratory media does not always provide the specificity and the sensitivity required, the use of selective media and incubation conditions still appears to be the method preferred by breweries. The media used depend on the type of sample, the specificity required and, for detection of wild yeasts, to some extent, the characteristics of the culture yeast. Among the media reported so far no single medium can be used to detect all members within a group of specific beer spoilage organisms and further work on the development of improved substrates are required both for bacteria and wild yeasts.

Effect of probiotic Lactobacillus strains on acute diarrhea in a cohort of nonhospitalized children attending day-care centers

Background. Certain strains of lactobacilli have been shown to promote recovery from rotavirus enteritis in hospitalized children. Few studies have examined the effect of probiotics in nonhospitalized children with mild diarrhea. Methods. We studied in a randomized placebo-controlled trial the effect of lyophilized Lactobacillus rhamnosus 19070-2 and Lactobacillus reuteri DSM 12246, 1010 colony-forming units of each strain twice daily for 5 days, on acute diarrhea in children in a cohort of children recruited from local day-care centers. The duration of diarrhea and assessment of stool consistency were recorded by the parents. Results. In patients treated with the selected Lactobacillus strains, the mean duration of diarrhea after intervention was reduced (76 h in patients treated with probiotics vs. 116 h in the placebo group;P = 0.05). In patients with diarrhea for <60 h before start of treatment (early intervention), a more pronounced effect of probiotics was found. The time to recovery after early treatment was 79 h vs. 139 h in the placebo group (P = 0.02); 1 of 17 patients treated early vs. 6 of 13 in the control group still had loose stools 120 h after start of treatment (P = 0.03). Conclusions. In children from day-care centers with mild gastroenteritis, the combination of L. rhamnosus 19070-2 and L. reuteri DSM 12246 was effective in reducing the duration of diarrhea.

The technological characteristics of Debaryomyces hansenii and Yarrowia lipolytica and their potential as starter cultures for production of Danablu

Abstract Six strains of Debaryomyces hansenii var. hansenii and Yarrowia lipolytica, respectively, originating from blue mould cheeses were examined for their potential use as starter cultures for the production of Danablu in laboratory studies. D. hansenii showed strong growth and assimilation of lactose, galactose, lactate and five out of six strains assimilated citric acid under the environmental conditions prevailing in Danablu during maturation at 10°C. Y. lipolytica was more sensitive to NaCl and did not assimilate lactose and galactose. Both yeasts hydrolysed tributyrin with the highest activity observed for Y. lipolytica. D. hansenii showed little if any release of free fatty acids from butterfat at 10°C. Y. lipolytica was strongly lipolytic. The strains of D. hansenii were not able to hydrolyse casein at 10°C whereas 4 of the 6 strains of Y. lipolytica degraded all components of the casein. Strain-specific interactions, in cheese agar resulting in inhibition of mycelial growth and sporulation of P. roqueforti was observed, especially for Y. lipolytica.

Yeast involved in fermentation of Coffea arabica in East Africa determined by genotyping and by direct denaturating gradient gel electrophoresis

Samples of Coffea arabica were collected during the different stages of the fermentation from two production sites in Tanzania. The yeasts community was identified by genotyping using ITS–PCR and sequence analysis of the D1/D2 domain of the 26S rRNA gene. For confirmation, denaturating gradient gel electrophoresis (DGGE) of PCR‐amplified 26S rRNA gene was performed to detect yeast directly from coffee samples without cultivation. Yeast counts were in the range 4.0 × 104 − 5.0 × 107 CFU/g with an increase during fermentation. Three yeasts species were dominant. The predominant yeast found during fermentation and drying was Pichia kluyveri. Pichia anomala was found in high numbers during drying of coffee beans. Hanseniaspora uvarum was the predominant yeast during fermentation but decreased during drying. Kluyveromyces marxianus, Candida pseudointermedia, Issatchenkia orientalis, Pichia ohmeri and Torulaspora delbrueckii occurred in concentrations of 103 CFU/g or below in coffee samples. Saccharomyces cerevisiae and Candida xestobii were not isolated by cultivation, but by the DGGE technique. A good agreement was found between the sequence analysis of the D1/D2 domain of the 26S rRNA gene and sequencing of the DGGE bands. Sequences of yeast isolates determined in this study have been deposited in the GenBank database under Accession Nos AY305664–AY305669 and AY305672–AY305683. Sequences of DGGE bands have also been deposited in the GenBank database under Accession Nos AY314789–AY314802. Copyright

Lactic acid fermentation of cassava dough into agbelima

The souring of cassava dough during fermentation into the fermented cassava meal, agbelima, was investigated. Four different types of traditional inocula were used to ferment the dough and increases in titrable acidity expressed as lactic acid from 0.31-0.38 to 0.78-0.91% (w/w) confirmed the fermentation to be a process of acidification. The microflora of all inocula and fermenting dough contained high counts of lactic acid bacteria, 10(8)-10(9) cfu/g in all inocula and 10(7)-10(8), 10(8)-10(9) and 10(9) cfu/g at 0, 24 and 48 h in all fermentations. Lactobacillus plantarum was the dominant species of lactic acid bacteria during all types of fermentation accounting for 51% of 171 representative isolates taken from various stages of fermentation. Other major lactic acid bacteria found were Lactobacillus brevis, 16%, Leuconostoc mesenteroides, 15% and some cocci including Streptococcus spp. whose numbers decreased with fermentation time. The lactic acid bacteria were responsible for the souring of agbelima through the production of lactic acid. All L. plantarum, L. brevis and L. mesenteroides isolates examined demonstrated linamarase as well as other enzymatic activities but did not possess tissue degrading enzymes like cellulase, pectin esterase and polygalacturonase. The aroma profile of agbelima did not vary with the type of inoculum used and in all samples the build-up of aroma compounds were dominated by a non-identified low molecular weight alcohol, 1-propanol, isoamyl alcohol, ethyl acetate, 3-methyl-1-butanol and acetoin. Substantial reductions occurred in the levels of cyanogenic compounds present in cassava during fermentation into agbelima and detoxification was enhanced by the use of inoculum.

Application of reuterin produced by Lactobacillus reuteri 12002 for meat decontamination and preservation.

Lactobacillus reuteri strain 12002 was used for reuterin production in the two-step fermentation process. A batch culture fermentation was used to produce a maximum biomass of L. reuteri. Then cells were harvested, resuspended in a glycerol-water solution, and anaerobically incubated to produce reuterin. The lyophilized supernatants (approximately 4000 activity units (AU) of reuterin per ml) were diluted in distilled water for decontamination and preservation trials. The MIC values of reuterin for Escherichia coli O157:H7 and Listeria monocytogenes were 4 and 8 AU/ml, respectively. In meat decontamination experiments, the surface of cooked pork was inoculated with either L. monocytogenes or E. coli O157:H7 at a level of approximately log10 5 CFU/cm2, incubated for 30 min at 7 degrees C, and decontaminated by exposure to reuterin (500 AU/ml). The bactericidal effect of reuterin was analyzed 15 s and 24 h after exposure at 7 degrees C. After 15 s of exposure to reuterin, viable numbers decreased by 0.45 and 0.3 log10 CFU/cm2 for E. coli O157:H7 and L. monocytogenes, respectively. After 24 h the numbers decreased by 2.7 log10 CFU/cm2 for E. coli O157:H7 and by 0.63 log10 CFU/cm2 for L. monocytogenes. In the same experiment, the combined effect of reuterin and lactic acid was also investigated. Adding lactic acid (5%, vol/vol) to reuterin significantly enhanced (P < or = 0.05) the efficacy of reuterin. No additional effect (P < or = 0.05) was found when ethanol (40%) was added to the mixture of reuterin and lactic acid. To evaluate the preservative effect of reuterin during meat storage, reuterin was added to raw ground pork contaminated with E. coli O157:H7 or L. monocytogenes. Reuterin at a concentration of 100 AU/g resulted in a 5.0-log10 reduction of the viability of E. coli O157:H7 after 1 day of storage at 7 degrees C. Reuterin at a concentration of 250 AU/g reduced the number of the viable cells of L. monocytogenes by log10 3.0 cycles after 1 week of storage at 7 degrees C.

Case Study of the Distribution of Mucosa-Associated Bifidobacterium Species, Lactobacillus Species, and Other Lactic Acid Bacteria in the Human Colon

ABSTRACT The distribution of mucosa-associated bacteria, bifidobacteria and lactobacilli and closely related lactic acid bacteria, in biopsy samples from the ascending, transverse, and descending parts of the colon from four individuals was investigated by denaturing gradient gel electrophoresis (DGGE). Bifidobacterial genus-specific, Lactobacillus group-specific, and universal bacterial primers were used in a nested PCR approach to amplify a fragment of the 16S rRNA gene. DGGE profiles of the bifidobacterial community were relatively simple, with one or two amplicons detected at most sampling sites in the colon. DGGE profiles obtained with Lactobacillus group-specific primers were complex and varied with host and sampling site in the colon. The overall bacterial community varied with host but not sampling site.