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PubMed2001

Advances in genomics for microbial food fermentations and safety.

The exponentially growing collection of genomic sequence information, the high-throughput analysis of expression products, and the ability to order this information using advanced bioinformatics are expected to affect biotechnology and life sciences in a profound and unprecedented way. These developments offer many possibilities to improve the functionality of fermentations by food-grade microorganisms and to increase the microbial safety of foods. It will be necessary to combine functional studies with comparative genomics approaches to provide effective strategies for improving the functionality and safety of foods.

Computational Biology↗
PubMed1986

Fermented foods, feeds, and beverages.

World population reached 5 billion people in 1986 and is expected to rise to 6 particularly severe in parts of Africa, particularly Ethiopia. Hunger and malnutrition accompany the poverty that is characteristic of the masses of the people in the developing world. Even in the United States, one of the most affluent countries, there has been a considerable increase in the number of homeless people including mothers and children living in the streets or in substandard housing. The indigenous fermented foods and beverages already consumed for centuries by hundreds of millions of the world's masses can be used in many cases to improve and extend the world's food and nutrition supply at a relatively low cost. Fermented foods, feeds and beverages are getting ever increasing attention particularly in the developing world and also in the developed world. This paper summarizes activities and advances related to fermented foods, feeds, and beverages over the past several years.

Journal Article↗
PubMed2000

Isolation, screening and characterization of bacteriocin-producing lactic acid bacteria isolated from traditional fermented food.

100 lactic acid bacterial strains isolated from traditional fermented foods (yoghurt, milk cream, sour dough and milk) were screened for bacteriocin production. Twenty six strains producing a nisin-like bacteriocin were selected. Most of these isolates gave only a narrow inhibitory spectrum, although one showed a broad inhibitory spectrum against the indicator strains tested, this strain was determined as Lactococcus lactis. The influence of several parameters on the fermentative production of nisin by Lactococcus lactis was studied. Production of nisin was optimal at 30 degrees C and in the pH range 5.5-6.3. The effect of different sulphur and nitrogen sources on Lactococcus lactis growth and nisin production was studied. Magnesium sulfate and manganese sulfate were found to be the best sulphur sources while triammonium citrate was the best inorganic nitrogen source and meat extract, peptone and yeast extract were the best organic nitrogen source for nisin production.

Bacteria↗
PubMed2006

Dietary deprivation of fermented foods causes a fall in innate immune response. Lactic acid bacteria can counteract the immunological effect of this deprivation.

Extrinsic factors such as maternal microbiota, bacterial load of the environment, diet and medication modulate the intestinal microbiota. Maturation and function of the immune system is influenced by established gut microbiota. In this work we describe the immunological effects of the dietary deprivation of fermented foods of healthy volunteers. Significant decreases in faecal lactobacillus and total aerobes counts and concentration of short chain fatty acids were observed following deprivation of fermented food of the normal diet. Moreover, a decrease in phagocytic activity in leukocytes was observed after two weeks of restricted diet. Therefore, the dietary deprivation of fermented foods could induce a decrease in innate immune response that might affect the capacity to respond against infections. The ingestion of a probiotic product containing the strains Lactobacillus gasseri CECT5714 and Lactobacillus coryniformis CECT5711 or a standard yogurt containing a conventional starter Lactobacillus delbrueckii sp. bulgaricus counteracted the fall in the immune response, although the probiotic product was more effective than the standard yogurt.

Adult↗
PubMed1981

Survey of aflatoxin-producing fungi in certain fermented foods and beverages in Thailand.

Aflatoxin-producing fungi were found in fermented foods and beverages: fermented rice (kaomak), soybean sauce (taotjo), peanut butter, soy sauce (shoyu), Thai red and white wine, and rice sugar wine. These foods were extracted directly and tested for aflatoxins by thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC). Four strains of aflatoxin-producing fungi were isolated from peanut butter, taotjo, and shoyu. Direct extracts of 10% of the peanut butters tested and 5% of the kaomak tested contained large amounts of aflatoxins. The HPLC procedures used in this experiment utilized chloroform-ethyl acetate (3:1).

Aflatoxins↗
PubMed1974

Acid protease production by fungi used in soybean food fermentation.

Growth conditions for maximum protease production by Rhizopus oligosporus, Mucor dispersus, and Actinomucor elegans, used in Oriental food fermentations, were investigated. Enzyme yields by all three fungi were higher in solid substrate fermentations than in submerged culture. The level of moisture in solid substrate must be at about 50 to 60%. Very little growth of these fungi was noted when the moisture of substrate was below 35%, whereas many fungi including most storage fungi generally grow well on solid substrate with that level of moisture. Among the three substrates tested-wheat bran, wheat, and soybeans-wheat bran was the most satisfactory one for enzyme production. The optimal conditions for maximum enzyme production of the three fungi grown on wheat bran were: R. oligosporus, 50% moisture at 25 C for 3 to 4 days; M. dispersus, 50 to 63% moisture at 25 C for 3 to 4 days; A. elegans, 50 to 63% moisture at 20 C for 3 days. Because these fungi are fast growing and require high moisture for growth and for enzyme synthesis, the danger of contamination by toxin-producing fungi would be minimal.

Endopeptidases↗
PubMed2002

New efficient amylase-producing strains of Lactobacillus plantarum and L. fermentum isolated from different Nigerian traditional fermented foods.

Amylolytic lactic acid bacteria (ALAB) were isolated from Nigerian traditional fermented foods (fufu, burukutu, ogi-baba and kunu-zakki) with the aim of selecting efficient amylase-producing strains. Nine isolates were characterized on the basis of their phenotypic and taxo-molecular characteristics. Three groups could be distinguished by their fermentation profiles and this was confirmed by DNA restriction analysis. Though fermentation profiles gave good identification of strain K9 (unique representative of group III) as Lactobacillus fermentum, they could not be used to ascertain the taxonomic position of strains of groups I and II. Analysis of partial 16S rRNA sequences led to the identification of these groups as L. plantarum strains and confirmed the species of strain K9 as L. fermentum. The two distinct phenotypic groups of L. plantarum differed in their use of D-xylose, L-arabinose, melibiose and were different from the previously described amylolytic L. plantarum A6 isolated from retted cassava in Congo. L. fermentum K9 was different from L. fermentum OgiE1 and Mw2 isolated from Benin maize sourdough and it is the first amylolytic L. fermentum described from Nigerian fermented products. Enzymatic profiles showed some differences between the strains of a similar fermentation group. One of the most relevant characteristics of the isolates was a higher yield of amylase production than those reported for previously described ALAB grown under the same conditions. Furthermore, all isolates were tolerant to an exposure at pH 2 and to bile salts.

Amylases↗
PubMed2000

Isolation of tannin-degrading lactobacilli from humans and fermented foods.

Lactobacilli with tannase activity were isolated from human feces and fermented foods. A PCR-based taxonomic assay revealed that the isolates belong to Lactobacillus plantarum, L. paraplantarum, and L. pentosus. Additional studies on a range of Lactobacillus species from established culture collections confirmed that this enzymatic activity is a phenotypic property common to these three species.

Animals↗
PubMed1997

Potential use of traditional fermented foods for weaning in Zimbabwe.

The current interest in the use of traditional fermented and malted foods for weaning is their potential to reduce the transmission of bacterial enteric pathogens through contaminated weaning foods as well as improving the nutritional value of the foods. This study was carried out to investigate the potential use of traditional fermented and malted foods for weaning in rural areas. Information was obtained by interviewing randomly selected 150 rural women with children under five years old. Ninety seven percent of the women had knowledge of some traditional fermented foods. The commonest fermented foods known by the women were mahewu (traditional fermented and malted sour, non-alcoholic cereal gruel), sour milk and sour porridge. Most of the women indicated that mahewu (94%), sour milk, (87%) and sour porridge (71%) were consumed by all family members. The majority of the women gave the fermented foods to infants from the age of four months. Although most of the infants were introduced to the fermented and malted foods from the age of four months, the foods were not given to infants very often, with the exception of mahewu. The storage period of the fermented foods ranged from one to three days. The results of this study show that mahewu, sour milk and sour porridge have a potential for use as weaning foods if they are promoted.

Child Nutrition Sciences↗
PubMed1993

The need for process optimization of African fermented foods and beverages.

Many papers have been published on various aspects of African fermented foods and beverages. The emphasis has been on the microorganisms used, and the nutritional status of the products after fermentation. The preparation of these products is still a traditional family art and the fermentation process is by uncontrolled inoculation. This has led to variations in the quality and stability of the products. Research efforts in this field are still based on old recipes transmitted from generation to generation due to the fact that the consumers are not easily influenced by innovations, and the apparent lack of biotechnological background. This paper gives a brief account of the fermentation process of some of the fermented products to show the varied pattern of the microbiology. The unpredictability of the complex microflora implicated in the fermentations, and the lack of adequate knowledge of the associated microbes are discussed. The paper suggests a number of steps to be taken to optimize the fermentation process as a means of maintaining the peculiar characteristics of each product and establishment of small-scale industrial production.

Africa↗
PubMed2004

Isolation and characterization of lactobacilli from some traditional fermented foods and evaluation of the bacteriocins.

Lactic acid bacteria (LAB) commonly used in food as starter cultures are known to produce antimicrobial substances such as bacteriocins and have great potential as food biopreservatives. LAB isolated from traditional fermented foods (appam batter and pickles) were screened for bacteriocin production. Two lactobacilli, LABB and LABP (one from each source) producing bacteriocins were characterized. Both the bacilli were homo-fermentative, catalase negative and micro-aerophilic in nature. LABB was found to be a thermobacterium growing at 45 degrees C while LABP was a streptobacterium growing at 15 degrees C. Both were able to grow at pH 4.5-8.6 but were intolerant to high salt concentration. They failed to produce gas from glucose as well as ammonia from arginine. Among the sugars examined they could not ferment arabinose, raffinose, rhamnose or xylose. Additionally, LABB could not ferment esculin, gluconate or mannose. LABB is identified as Lactobacillus acidophilus while LABP as Lb. casei. Their bacteriocins showed a broad inhibitory spectrum against the indicator organisms tested. They were active below pH 8.0 and after autoclaving as well. There was a complete loss of activity when treated with proteolytic enzymes such as trypsin indicating the proteinaceous nature of the active molecules. SDS-PAGE of partially purified bacteriocins indicated the molecular mass of the bacteriocin as 3.8 and 4.5 kDa for LABB and LABP respectively.

Bacteria↗
PubMed2004

Genotypic analyses of lactobacilli with a range of tannase activities isolated from human feces and fermented foods.

A total of 77 tannase producing lactobacilli strains isolated from human feces or fermented foods were examined for their genotypic profiles and intensities of tannase production. With a PCR-based assay targeting recA gene, all strains except one isolate were assigned to either Lactobacillus plantarum, L. paraplantarum, or L. pentosus whereas a 16/23S rDNA targeted PCR-based assay identified all except 6 isolates (inclusive of the above one isolate) as one of the closely related species. Subsequent DNA/DNA hybridization assays revealed that these 6 exceptional isolates showed low homology (between 1.2% and 55.8% relative DNA binding) against type strains of the three species. Supplemental carbohydrate fermentation profiles on the 6 isolates indicated that two of them were identified as L. acidophilus, one as Pediococcus acidilactici, one as P. pentosaceus, and two remained unidentifiable. The evidence suggests that the 16/23S rDNA targeted PCR assay can be used as a reliable identification tool for the closely related lactobacilli, and that the tannase gene is widely distributed within members of the Lactobacillaceae family. Meanwhile, a randomly amplified polymorphism DNA (RAPD) analysis revealed that all except 8 isolates were well allocated in 4 major RAPD clusters, though not species specific, consisting of two L. plantarum predominant clusters, one L. paraplantarum predominant, and one L. pentosus predominant. The RAPD patterns of the 8 non-clustered isolates, which consisted of the 6 unidentifiable isolates and 2 isolates identified as L. pentosus, were <40% similarity to those belonging to the 4 clusters. A quantitative assay of the tannase activities showed that there was a marked variation in the activities among the strains, which did not correlate with either species identification or clustering by RAPD.

Carbohydrates↗
PubMed2003

Enterococcus faecium RZS C5, an interesting bacteriocin producer to be used as a co-culture in food fermentation.

Enterocins, bacteriocins produced by enterococci, are gaining interest because of their industrial potential. Due to its bacteriocin production, Enterococcus faecium RZS C5, a natural cheese isolate, has a strong activity towards Listeria monocytogenes. For this reason, the strain may be applicable as a bacteriocin-producing co-culture in food fermentation in order to reduce the risk on Listeria outgrowth. The strain displays remarkable bacteriocin production kinetics. Whereas most lactic acid bacteria produce bacteriocin in a growth-associated way until the beginning of the stationary phase, bacteriocin production by E. faecium RZS C5 in MRS broth at controlled pH values below 7.5 is characterised by a boost of bacteriocin activity levels in the very early growth phase. In addition, bacteriocin production kinetics are closely linked to the environmental and cultural conditions. However, no straightforward statement about the effect of environmental stress on bacteriocin production can be made since the effect is dependent on the type of stress applied. Kinetic experiments in milk and on pilot scale, applying Cheddar cheese-making conditions, have indicated that the strain may be effective as a bacteriocin-producing co-culture. Further research is needed to evaluate the use of E. faecium RZS C5 as a co-culture for the production of fermented sausage.

Animals↗
PubMed2005

Comparison of four methods to enumerate probiotic bifidobacteria in a fermented food product.

Four methods of enumeration were compared by monitoring levels of probiotic bifidobacteria in fermented oat drink during storage. Strains of Bifidobacterium longum and B. lactis were quantified by plate counts, fluorescent in situ hybridization (FISH), quantitative real-time PCR and commercial LIVE/DEAD BacLight bacterial viability kit, and the methods were further developed to suit the enumeration of bifidobacteria in fermented foods. Plate counts of both B. lactis and B. longum were lower than the PCR and FISH counts. The LIVE/DEAD counts of B. lactis were comparable to PCR and FISH counts. The plate counts of B. lactis were slightly but significantly lower than LIVE/DEAD counts, suggesting that the cells that were not able to grow on plates may have become dormant. The plate counts of B. longum were several log units lower than LIVE/DEAD counts, suggesting that a remarkable part of the cells were dormant. Real-time PCR and FISH were shown to suit the quantification of the total amount of probiotic bifidobacteria in foods. Plate counts and LIVE/DEAD counts provided conflicting information on viability especially in the case of B. longum. We conclude that the choice of enumeration method for probiotic bacteria may have significant effect on the results of the analysis. The strain-specific properties and the objects of the analysis should be taken into account when enumeration methods for different probiotic strains are chosen.

Bifidobacterium↗
PubMed2006

Isolation and characterization of lactic acid bacteria from suan-tsai (fermented mustard), a traditional fermented food in Taiwan.

AIMS: To isolate, characterize, and identify lactic acid bacteria (LAB) in suan-tsai (fermented mustard), a traditional fermented food in Taiwan. METHODS AND RESULTS: Suan-tsai samples were collected at five time points from a fixed fermenting bucket. Fifty cultures were isolated from suan-tsai samples, and isolates were divided into classes by phenotype and then into groups by restriction-fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Phenotypic and biochemical characteristics identified two different bacterial groups (A and B), and the results showed that Pediococcus pentosaceus was the most abundant LAB during the initial fermentation time. However, the more NaCl-tolerant species Tetragenococcus halophilus took the place of P. pentosaceus and became the most abundant LAB later. All isolates were grown in de Man, Rogosa, and Sharpe (MRS) broth containing 6% NaCl, but T. halophilus could grow only in MRS broth containing 10% NaCl. CONCLUSIONS: These results suggest that the LAB P. pentosaceus and T. halophilus play roles in the fermentation of suan-tsai. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the distribution and varieties of LAB that exist in the suan-tsai fermentation process.

Colony Count, Microbial↗
PubMed2006

Isolation and characterization of lactic acid bacteria from dochi (fermented black beans), a traditional fermented food in Taiwan.

AIMS: To isolate, characterize and identify lactic acid bacteria (LAB) in dochi (fermented black beans), a traditional fermented food in Taiwan. METHODS AND RESULTS: A total of 30 samples were collected from three different dochi producers and analysed after different periods of storage. Fifty-two cultures of LAB were isolated from dochi samples and the isolates were divided into classes by phenotype and then into groups by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Phenotypic and biochemical characteristics identified six different bacterial groups (A-F) and showed that the majority of the isolates were homofermentative LAB. Enterococcus faecium was the most abundant of the dochi-isolated LAB. All isolated LAB were able to grow in MRS broth containing 6% NaCl, but only Enterococcus, Pediococcus and Tetragenococcus species could grow in MRS broth containing 10% NaCl. Furthermore, antibacterial activities of isolates were determined, and four isolates showed inhibitory activities against the indicator strain Lactobacillus sakei JCM 1157(T). CONCLUSIONS: These results suggest that Ent. faecium is the main LAB present during the fermentation of dochi. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the distribution and varieties of LAB that exist in the dochi fermentation process.

Antibiosis↗
PubMed1994

Reverse dot blot hybridization: a useful method for the direct identification of lactic acid bacteria in fermented food.

A rapid method for a reliable and simultaneous identification of different lactic acid bacteria in fermented food has been developed. Various 16S and 23S rRNA-targeted, species-specific oligonucleotides were applied as capture probes in a non-radioactive reverse dot blot hybridization. A simple and fast DNA extraction method in combination with in vitro amplification of rRNA gene fragments enables the direct detection of typical starter organisms without any preceding enrichment or cultivation steps. Various lactic acid bacteria occurring in cheese, yogurt, sausages, sauerkraut and sourdough could be identified at the species level within 1 day.

Base Sequence↗