Tempe fermentation, innovation and functionality: update into the third millenium.
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Chronic Disease↗
Biomedical subjects
M J R Nout
Publications and source records attributed to M J R Nout.
Effect of individual amino acids and glucose on activation and germination of Rhizopus oligosporus sporangiospores in tempe starter.
AIM: To understand the conditions promoting activation and germination of spores, and to contribute to the control of tempe starters. METHODS AND RESULTS: Using microscopic counts of fluorescent labelled spores, the following results were obtained: (1) L-alanine plays an important role (of the same order as that of peptone) in stimulation of germination of dormant spores. Alanine can satisfy the requirements of carbon as well as nitrogen for spore germination; (2) L-proline, on the other hand, inhibits alanine uptake presumably by blocking/congesting transporters of spore cells, resulting in apparent low viability on agar media; (3) L-leucine and L-isoleucine slightly favour spore germination while L-arginine and L-lysine do not have any stimulating effect; (4) The stimulatory role of glucose was only evident in the presence of phosphate (in minimal medium); when glucose is used in the absence of phosphate, either alone or in combination with single amino acids its role is hardly distinguishable; (5) Phosphate plays a facilitating role in spore germination. CONCLUSIONS: Glucose and amino acids play important roles in activation and germination of sporangiospores of Rhizopus oligosporus in tempe starter (stored for 12 months). The ability and rate of germination of dormant/old sporangiospores of R. oligosporus, depend on their ability for uptake of individual amino acids and/or glucose. SIGNIFICANCE AND IMPACT OF STUDY: New light was shed on the counteractive role of proline and the stimulating effect of phosphate. Soybeans subjected to traditional preparation for tempe making are heavily leached; germination of starter spores on such beans is sub-optimal, and bean processing could be optimized.
Alanine↗
Dormancy, activation and viability of Rhizopus oligosporus sporangiospores.
Interruption of dormancy to improve viability of Rhizopus oligosporus sporangiospores is crucial for the application of stored starter cultures for fungal (tempe) production. We aimed to assess the extent of dormancy and factors that could result in activation. Whereas heat treatments were unsuccessful, Malt Extract Broth (MEB) showed to be a good activation medium, with 80% of dormant spores being activated as measured by fluorescence microscopy using a fluorescent marker, compared with 11% with the control. Peptone and yeast extract but not glucose played an important role in activating dormant spores. Metabolically active (fluorescent) and swollen spores, followed by germ tubes were obtained after activation in MEB for 25 min., 2 and 4 h, respectively, at 37 degrees C. Simultaneously, some interesting transitions took place. Dormant spores represent 85-90% of the total spores at harvest and after drying. Their number decreased to 21-32% after activation with MEB with a concomitant increase of metabolically active spores. As a result of storage, some dormancy was lost, yielding an increase of active spores from 11.2% at harvest to 28.8% after 3 months storage. Levels of active spores were well correlated with their viability. By activation of dormant spores, their viability increased; levels of viable and active spores were maximum in 1 month old starter (61.7% and 75.9% of total spores, respectively) but gradually decreased with concomitant increase of the number of dead spores.
Colony Count, Microbial↗
An antifungal compound produced by Bacillus subtilis YM 10-20 inhibits germination of Penicillium roqueforti conidiospores.
AIMS: To identify and characterize an antifungal compound produced by Bacillus subtilis YM 10-20 which prevents spore germination of Penicillium roqueforti. METHODS AND RESULTS: The antifungal compound was isolated by acid precipitation with HCl. This compound inhibited fungal germination and growth. Identification by HPLC and mass spectrometry analysis showed high similarity to iturin A. Permeabilization and morphological changes in P. roqueforti conidia in the presence of the inhibitor were revealed by fluorescence staining and SEM, respectively. CONCLUSOINS: The iturin-like compound produced by B. subtilis YM 10-20 permeabilizes fungal spores and blocks germination. SIGNIFICANCE AND IMPACT OF THE STUDY: Fluorescence staining in combination with flow cytometry and scanning electron microscopy are efficient tools for assessing the action of antifungal compounds against spores. Iturin-like compounds may permeabilize fungal spores and inhibit their germination.
Antifungal Agents↗
Effect of fermented soya beans on diarrhoea and feed efficiency in weaned piglets.
AIMS: To evaluate anti-diarrhoeal and growth enhancing properties of fermented soya beans in weaned piglets. METHODS AND RESULTS: In a first phase piglet diet, toasted full-fat soya beans (20%) were replaced with either cooked soya beans or Rhizopus microsporus or Bacillus subtilis fermented soya beans. The effect on the incidence, severity and duration of diarrhoea in enterotoxigenic Escherichia coli (ETEC)-challenged weaned piglets was determined (pen trial, 24 piglets per treatment). Severity of diarrhoea was significantly less on the diet with Rhizopus-fermented soya beans compared with the control diet containing toasted soya beans. Piglets fed fermented soya beans showed increased feed intake (13 and 12%), average daily weight gain (18 and 21%) and feed efficiency (3 and 8%) (for Rhizopus and Bacillus-fermented soya beans, respectively). However, in the treatment groups an unequal mortality and a potential unequal distribution of receptor-positive piglets were observed. CONCLUSIONS: Cooked and fermented soya beans could be beneficial in the control of diarrhoea in ETEC-challenged weaned piglets (particularly Rhizopus fermented) and significantly improved weight gain and feed intake (particularly Bacillus fermented). SIGNIFICANCE AND IMPACT OF THE STUDY: Fermented soya beans could offer benefits with respect to the control of diarrhoea and feed efficiency in piglets.
Animal Feed↗
Diversity and functionality of Bacillus and related genera isolated from spontaneously fermented soybeans (Indian Kinema) and locust beans (African Soumbala).
A total of 126 isolates of Bacillus and related genera from indigenous, spontaneously fermented soybeans (Kinema) and locust beans (Soumbala) were characterized with the purpose of defining interspecific, as well as intraspecific relationships among the components of their microflora. B. subtilis was the dominant species, and species diversity was more pronounced in Soumbala than in Kinema. While from Kinema, six species were isolated (B. subtilis, B. licheniformis, B. cereus, B. circulans, B. thuringiensis and B. sphaericus), in Soumbala, the species found were B. subtilis, B. thuringiensis, B. licheniformis, B. cereu, B. badius, Paenibacillus alvei, B. firmus, P. larvae, Brevibacillus laterosporus, B. megaterium, B. mycoides and B. sphaericus. Genomic diversity in the isolates of B. subtilis was investigated by random amplified polymorphic DNA (RAPD) analysis using the polymerase chain reaction (PCR). The RAPD-PCR fingerprint analysis showed a high level of diversity. With more than 90% similarity, all 52 RAPD subdivisions were source and continent-wise homogeneous. Profiles of carbon source fermentation also showed a wide but corresponding phenotypic diversity, largely corresponding with RAPD subdivisions. The various strains were tested for several criteria for functionality in soybean fermentation, viz. protein degradation, pH increase, and development of desirable stickiness caused by viscous exopolymers. Profiles of functionality, based upon estimations of pH, free amino nitrogen and stickiness were associated with genotypic and phenotypic profiles. Notwithstanding the heterogenous fermentation results for some genotypic profiles, a ranking of RAPD groups is possible and can be useful in the further selection and study of B. subtilis strains.
Bacillus↗
Inhibition of adhesion of enterotoxigenic Escherichia coli K88 by soya bean tempe.
AIMS: Tempe is a traditional fungal fermented food made from soaked and cooked soya beans. It has been associated with antidiarrhoeal characteristics. This study investigated potential inhibitory effects of tempe on enterotoxigenic Escherichia coli (ETEC) K88. METHODS AND RESULTS: Soya beans were soaked, cooked and subsequently fermented using several Rhizopus spp. Water-soluble filter-sterile extracts were tested for their ability to inhibit growth of E. coli and several indicator microorganisms and to inhibit adhesion of ETEC K88. Antimicrobial activity was found against Bacillus stearothermophilus only. ETEC K88-induced haemagglutination of hamster red blood cells was strongly inhibited by a number of tempe extracts and hardly by the cooked soya bean extract. Furthermore, several tempe extracts were able to inhibit adhesion of ETEC K88 to piglet small intestinal brush-border membranes. CONCLUSIONS: Tempe appeared to interfere with ETEC K88 adhesion rather than showing growth inhibitory properties. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicate that tempe could exert an antagonistic effect against ETEC through inhibition of adhesion and might therefore have a protective effect against ETEC K88 infection in pigs. Hence, tempe could have potential to use as a feed supplement in the diet of weaned piglets.
Animals↗