Improvement of Carotenoid-Synthesizing Yeast Rhodotorula rubra by Chemical Mutagenesis

2004 ◽  
Vol 59 (1-2) ◽  
pp. 99-103 ◽  
Author(s):  
Ginka I. Frengova ◽  
Emilina D. Simova ◽  
Dora M. Beshkova
Keyword(s):  
Mixed Culture ◽  
Culture Fluid ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Bulgaricus ◽  
Chemical Mutagenesis ◽  
Rhodotorula Rubra ◽  
Total Carotenoids ◽  
Mass Fractions ◽  
The Individual ◽  
Β Carotene

A mutant Rhodotorula rubra with enhanced carotenoid-synthesizing activity for synthesizing total carotenoids and β-carotene was obtained by N-methyl-N′-nitro-N-nitrosoguanidine mutagenesis. When co-cultivated with yogurt starter bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus) in whey ultrafiltrate it produced 15.7 mg total carotenoids l-1 culture fluid or 946 μg total carotenoids g-1 dry cells of which 71% was β-carotene. Grown as a monoculture in glucose substrate, the mutant shown 1.4 times lower carotenoid-synthesizing activity, and the relative share of β-carotene in the total carotenoids was lower (63%). The individual pigments torulene and torularhodin were identified, whose mass fractions were (29% and 7%) and (24% and 4%), respectively, for the mutant grown as a monoculture and as a mixed culture with the yogurt bacteria.

β-Carotene-Rich Carotenoid-Protein Preparation and Exopolysaccharide Production by Rhodotorula rubra GED8 Grown with a Yogurt Starter Culture

2006 ◽  
Vol 61 (7-8) ◽  
pp. 571-577 ◽  
Author(s):  
Ginka I. Frengova ◽  
Emilina D. Simova ◽  
Dora M. Beshkova
Keyword(s):  
Starter Culture ◽  
Culture Fluid ◽  
Streptococcus Thermophilus ◽  
Dry Weight ◽  
Lactobacillus Bulgaricus ◽  
Carotenoid Pigment ◽  
Rhodotorula Rubra ◽  
Protein Preparation ◽  
Carotenoid Composition ◽  
Β Carotene

The underlying method for obtaining a β-carotene-rich carotenoid-protein preparation and exopolysaccharides is the associated cultivation of the carotenoid-synthesizing lactose-negative yeast strain Rhodotorula rubra GED8 with the yogurt starter culture (Lactobacillus bulgaricus 2-11 + Streptococcus thermophilus 15HA) in whey ultrafiltrate (45 g lactose/l) with a maximum carotenoid yield of 13.37 mg/l culture fluid on the 4.5th day. The chemical composition of the carotenoid-protein preparation has been identified. The respective carotenoid and protein content is 497.4 μg/g dry cells and 50.3% per dry weight, respectively. An important characteristic of the carotenoid composition is the high percentage (51.1%) of β- carotene (a carotenoid pigment with the highest provitamin A activity) as compared to 12.9% and 33.7%, respectively, for the other two individual pigments - torulene and torularhodin. Exopolysaccharides (12.8 g/l) synthesized by the yeast and lactic acid cultures, identified as acid biopolymers containing 7.2% glucuronic acid, were isolated in the cell-free supernatant. Mannose, produced exclusively by the yeast, predominated in the neutral carbohydrate biopolymer component (76%). The mixed cultivation of R. rubra GED8 with the yogurt starter (L. bulgaricus 2-11 + S. thermophilus 15HA) in ultrafiltrate under conditions of intracellular production of maximum amount of carotenoids and exopolysaccharides synthesis enables combined utilization of the culture fluid from the fermentation process.

Effect of Aeration on the Production of Carotenoid Pigments by Rhodotorula rubra-lactobacillus casei Subsp. casei Co-Cultures in Whey Ultrafiltrate

2003 ◽  
Vol 58 (3-4) ◽  
pp. 225-229 ◽  
Author(s):  
Emilina D. Simova ◽  
Ginka I. Frengova ◽  
Dora M. Beshkova
Keyword(s):  
Maximum Concentration ◽  
Lactobacillus Casei ◽  
Cheese Whey ◽  
Culture Fluid ◽  
Carotenoid Pigments ◽  
Air Flow Rate ◽  
Rhodotorula Rubra ◽  
Total Carotenoids ◽  
Β Carotene ◽  
Carotene Synthesis

Under intensive aeration (1.3 l/l min) the associated growth of Rhodotorula rubra GED2 and Lactobacillus casei subsp. casei in cheese whey ultrafiltrate (55 g lactose/l) proceeded effectively for both cultures with production of maximum carotenoids (12.4 mg/l culture fluid). For maximum amount of carotenoids synthesized in the cell, the yeast required more intensive aeration than the aeration needed for synthesis of maximum concentration of dry cells. Maximum concentration of carotenoids in the cell (0.49 mg/g dry cells) was registered with air flow rate at 1.3 l/l min, and of dry cells (27.0 g/l) at 1.0 l/l min. An important characteristic of carotenogenesis by Rhodotorula rubra GED2 + Lactobacillus casei subsp. casei was established - the intensive aeration (above 1.0 l/l min) stimulated β-carotene synthesis (60% of total carotenoids).

Thermograms ofStreptococcus thermophilusandLactobacillus bulgaricusin single and mixed culture in milk medium

1979 ◽  
Vol 46 (3) ◽  
pp. 485-496 ◽  
Author(s):  
Paul R. Monk
Keyword(s):  
Mixed Culture ◽  
Streptococcus Thermophilus ◽  
Ph Control ◽  
Lactobacillus Bulgaricus ◽  
Stimulation Of

SummaryMicrobial thermograms have been used to investigate the growth ofStreptococcus thermophilusandLactobacillus bulgaricusin single and mixed culture in milk medium. Growth has been observed with different ratios of the strains in the inoculum and, at one ratio, the effect of the amount of inoculum. The effect of serial sub-culture both with and without pH control has been observed, and stimulation ofStr. thermophilusby cell-free fitrates ofL. bulgaricushas been examined. The development of the technique is discussed in terms of the application of microbial thermograms in selecting cultures for incorporation into mixtures and evaluating their performance.

Effect of Incubation Temperature and Heat Treatments of Milk from Cow and Buffalo on Acid and Flavor Production by Streptococcus thermophilus and Lactobacillus bulgaricus

1980 ◽  
Vol 43 (5) ◽  
pp. 399-400 ◽  
Author(s):  
JASJIT SINGH ◽  
ADARSH KHANNA ◽  
HARISH CHANDER
Keyword(s):  
Mixed Culture ◽  
Proteolytic Activity ◽  
Milk Sample ◽  
Incubation Temperature ◽  
Streptococcus Thermophilus ◽  
Heat Treatments ◽  
Buffalo Milk ◽  
Maximum Amount ◽  
Lactobacillus Bulgaricus ◽  
Acetaldehyde Production

Variations in production of acid and acetaldehyde and proteolytic activity by pure and mixed cultures of Streptococcus thermophilus and Lactobacillus bulgaricus in response to incubation temperature were determined using cow and buffalo milk. S. thermophilus and the mixed culture produced more acid and acetaldehyde at 37 than at 42 C, while the reverse was true for L. bulgaricus in both types of milk. The largest amount of acid was produced by S. thermophilus in both types of milks heated at 65 C for 30 min, while L. bulgaricus produced the maximum amount of acid in milks heated at 85 C for 10 min. In the mixed culture, increased acid and acetaldehyde production were noted in milk sample steamed for 30 min.

scholarly journals Mixed-Culture Transcriptome Analysis Reveals the Molecular Basis of Mixed-Culture Growth in Streptococcus thermophilus and Lactobacillus bulgaricus

2010 ◽  
Vol 76 (23) ◽  
pp. 7775-7784 ◽  
Author(s):  
Sander Sieuwerts ◽  
Douwe Molenaar ◽  
Sacha A. F. T. van Hijum ◽  
Marke Beerthuyzen ◽  
Marc J. A. Stevens ◽  
...  
Keyword(s):  
Amino Acids ◽  
Folic Acid ◽  
Mixed Culture ◽  
Transcriptome Profiling ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Lactobacillus Bulgaricus ◽  
Systematic Analysis ◽  
Culture Growth ◽  
Branched Chain

ABSTRACT Many food fermentations are performed using mixed cultures of lactic acid bacteria. Interactions between strains are of key importance for the performance of these fermentations. Yogurt fermentation by Streptococcus thermophilus and Lactobacillus bulgaricus (basonym, Lactobacillus delbrueckii subsp. bulgaricus) is one of the best-described mixed-culture fermentations. These species are believed to stimulate each other's growth by the exchange of metabolites such as folic acid and carbon dioxide. Recently, postgenomic studies revealed that an upregulation of biosynthesis pathways for nucleotides and sulfur-containing amino acids is part of the global physiological response to mixed-culture growth in S. thermophilus, but an in-depth molecular analysis of mixed-culture growth of both strains remains to be established. We report here the application of mixed-culture transcriptome profiling and a systematic analysis of the effect of interaction-related compounds on growth, which allowed us to unravel the molecular responses associated with batch mixed-culture growth in milk of S. thermophilus CNRZ1066 and L. bulgaricus ATCC BAA-365. The results indicate that interactions between these bacteria are primarily related to purine, amino acid, and long-chain fatty acid metabolism. The results support a model in which formic acid, folic acid, and fatty acids are provided by S. thermophilus. Proteolysis by L. bulgaricus supplies both strains with amino acids but is insufficient to meet the biosynthetic demands for sulfur and branched-chain amino acids, as becomes clear from the upregulation of genes associated with these amino acids in mixed culture. Moreover, genes involved in iron uptake in S. thermophilus are affected by mixed-culture growth, and genes coding for exopolysaccharide production were upregulated in both organisms in mixed culture compared to monocultures. The confirmation of previously identified responses in S. thermophilus using a different strain combination demonstrates their generic value. In addition, the postgenomic analysis of the responses of L. bulgaricus to mixed-culture growth allows a deeper understanding of the ecology and interactions of this important industrial food fermentation process.

scholarly journals Aceitação sensorial e caracterização de frozen yogurt de leite de cabra com adição de cultura probiótica e prebiótico

2009 ◽  
Vol 39 (9) ◽  
pp. 2595-2600 ◽  
Author(s):  
Larissa de Lima Alves ◽  
Neila Silvia Pereira dos Santos Richards ◽  
Larissa Vargas Becker ◽  
Diego Fontana de Andrade ◽  
Liana Inês Guidolin Milani ◽  
...  
Keyword(s):  
Lactobacillus Acidophilus ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Bulgaricus ◽  
Bifidobacterium Animalis ◽  
Frozen Yogurt

O leite de cabra é recomendado para pessoas intolerantes ao leite de vaca e/ou portadoras de desordens gastrintestinais. frozen yogurt elaborado a partir de iogurte de leite de cabra foi acrescido de 1% de prebiótico (inulina), 0,25% de cultura starter (Streptococcus thermophilus e Lactobacillus bulgaricus) e 0,25% de cultura probiótica (Bifidobacterium animalis e Lactobacillus acidophilus) para verificar seu potencial probiótico (após sete e 120 dias de armazenamento), sua qualidade físico-química e sua aceitação sensorial. Durante a estocagem, houve redução de células viáveis da flora microbiana, principalmente dos probióticos. Ainda assim, o produto apresenta potencialidade probiótica pela soma de B. animalis e L. acidophilus atingir o mínimo desejável até o fim do armazenamento. Os valores de extrato seco total (26,6±0,2%), proteína (3,0±0,2), gordura (2,6±0,1%), pH (5,5±0,01) e ácido láctico (0,2±0,01%) encontram-se semelhantes aos relatados em outros trabalhos para o mesmo produto. A avaliação sensorial foi realizada por 50 provadores não treinados em teste com escala hedônica de sete níveis e intenção de compra. O produto recebeu bons escores para aparência global, cor, aroma e sabor; já textura e sabor residual obtiveram menores índices de aceitação. Na intenção de compra, 61% dos avaliadores declararam que comprariam o produto, contra 39% que não comprariam. Nessas condições, demonstra-se a viabilidade de elaboração de frozen yogurt de leite caprino acrescido de pre- e probióticos.

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