RESUMEN
ABSTRACT In order for the use of biological carotenoids to become feasible, it is necessary to have adequate low cost sources and improved methods of cultivation. The aim of this study was to evaluate the effect of supplementation with nitrogen, phosphorus, zinc, and magnesium, on the biomass and carotenoid volumetric production by yeast Rhodotorula rubra L02 using a complex medium (sugarcane juice) and synthetic media (sucrose and maltose) as substrates. The experimental design used for each substrate was randomized in blocks with 16 treatments and 3 repetitions. The treatments were compound for 15 different combinations of nutrients (N; Mg; Zn; P, N + Mg; N + Zn; N + P; Mg + Zn; Mg + P; Zn + P; N + P + Zn; N + P + Mg; N + Zn + Mg; P + Zn + Mg; N + Zn + Mg + P) alone and combined, and a control. The results were submitted to analysis of variance and Tukey test at 5% significance level. Among the treatments evaluated, the highest production of dry biomass, with both maltose and sucrose, was observed for Mg (1.60 g/L and 1.94 g/L, respectively). Additionally, another treatment that stood out in terms of biomass production was the control treatment with maltose (1.54 g/L). After the incubation time, killer activity was not observed since there was no formation of inhibition halo around the L02 yeast.
Asunto(s)
Rhodotorula/metabolismo , Carotenoides/biosíntesis , Medios de Cultivo/síntesis química , Saccharum/microbiología , Rhodotorula/crecimiento & desarrollo , Rhodotorula/genética , Biomasa , Medios de Cultivo/metabolismo , Medios de Cultivo/química , Saccharum/metabolismo , Nitrógeno/metabolismoRESUMEN
In order for the use of biological carotenoids to become feasible, it is necessary to have adequate low cost sources and improved methods of cultivation. The aim of this study was to evaluate the effect of supplementation with nitrogen, phosphorus, zinc, and magnesium, on the biomass and carotenoid volumetric production by yeast Rhodotorula rubra L02 using a complex medium (sugarcane juice) and synthetic media (sucrose and maltose) as substrates. The experimental design used for each substrate was randomized in blocks with 16 treatments and 3 repetitions. The treatments were compound for 15 different combinations of nutrients (N; Mg; Zn; P, N+Mg; N+Zn; N+P; Mg+Zn; Mg+P; Zn+P; N+P+Zn; N+P+Mg; N+Zn+Mg; P+Zn+Mg; N+Zn+Mg+P) alone and combined, and a control. The results were submitted to analysis of variance and Tukey test at 5% significance level. Among the treatments evaluated, the highest production of dry biomass, with both maltose and sucrose, was observed for Mg (1.60g/L and 1.94g/L, respectively). Additionally, another treatment that stood out in terms of biomass production was the control treatment with maltose (1.54g/L). After the incubation time, killer activity was not observed since there was no formation of inhibition halo around the L02 yeast.
Asunto(s)
Carotenoides/biosíntesis , Medios de Cultivo/síntesis química , Rhodotorula/metabolismo , Saccharum/microbiología , Biomasa , Medios de Cultivo/química , Medios de Cultivo/metabolismo , Nitrógeno/metabolismo , Rhodotorula/genética , Rhodotorula/crecimiento & desarrollo , Saccharum/metabolismoRESUMEN
Escherichia coli produtoras de toxina de Shiga (STEC) são considerados importantes patógenos de origem alimentar que apresentam o trato intestinal de ruminantes domésticos, principalmente bovinos, seu reservatório natural. Esses microrganismos estão associados com doenças severas em humanos, tais como colite hemorrágica (CH) e síndrome urêmica hemolítica (SHU). Este trabalho teve como objetivos avaliar a ocorrência de STEC em diferentes fontes, ambientais ou não, da criação e abate de bovinos confinados. Além disso, detectar a presença dos genes stx1, stx2, ehxA e eaeA; identificar cepas O157:H7 através da pesquisa do gene uidA; evidenciar a capacidade de produção de Stx e de Eh; identificar variantes de stx e de eaeA; e determinar os sorotipos a diversidade genética das cepas de STEC. A avaliação da presença dos genes (stx1, stx2, ehxA e eaeA) e da produção de Eh foi utilizada como triagem para a seleção de cepas possivelmente patogênicas, sendo que do total de 628 isolados avaliados, foram selecionadas 47 cepas STEC típicas e outras 12 consideradas como atípicas. Das STEC típicas 80,9% foram isolados provenientes de amostras de fezes, enquanto 19,1% foram de amostras de carcaças. Seis cepas isoladas de fezes e 1 de carcaça foram sorotipificadas como 0157:H7, todas positivas para a presença do gene uidA. Além do sorogrupo 0157, nenhum outro, dentre os principais causadores de surtos e casos esporádicos de CH e SHU, foi detectado...
Asunto(s)
Animales , Bovinos , /genética , /patogenicidad , Microbiología de Alimentos , Técnicas In Vitro , Infecciones por Escherichia coli/genética , Infecciones por Escherichia coli/metabolismo , Productos de la Carne/análisis , Productos de la Carne/microbiología , Productos de la Carne/toxicidad , Toxina Shiga/genética , Toxina Shiga/toxicidad , Electroforesis en Gel de Agar/métodos , Medios de Cultivo/análisis , Medios de Cultivo/síntesis química , Reacción en Cadena de la Polimerasa/métodosRESUMEN
The aims of this work were to improve a basal synthetic medium (BM) for the growth of Lactobacillus plantarum strains and to establish their amino-acid requirements. Amino-acid use was analyzed in the most nutritionally demanding bacterium. First, the improved BM (L. plantarum synthetic medium [LPSM]) was created by increasing some vitamins in the BM, especially p-aminobenzoic acid, vitamin B(12), and biotin; 5-fold phenylalanine, histidine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, and tryptophan; and 10-, 60-, and 75-fold valine, arginine, and tyrosine, respectively. With these additions, the N8 and N4 strains of L. plantarum grew rapidly to reach final cell densities similar to those obtained in Mann-Rogosa-Sharpe medium. When cysteine, leucine, valine, isoleucine, threonine, and glutamic acid were individually removed from this medium, bacterial growth significantly decreased or ceased, indicating that these amino acids are essential for growth. The N4 strain also required lysine and tryptophan in addition to the six amino acids necessary for growth. L. plantarum N4 mainly consumed essential amino acids, such as valine, lysine, cysteine, and threonine as well as the stimulatory amino acid, arginine. Thus, the BM was improved mainly on the basis of annulling limitations with respect to amino acids. With this, improved medium cell densities in the order of 10(9) colony-forming units/mL have been achieved, indicating that LPSM medium could be used for conducting metabolic and genetic studies on L. plantarum. Their low levels in orange juice suggest that these amino acids may not satisfy the total nitrogen requirement for the development of L. plantarum in the natural environment.
Asunto(s)
Medios de Cultivo/síntesis química , Lactobacillus plantarum/crecimiento & desarrollo , Aminoácidos/metabolismo , Medios de Cultivo/metabolismoRESUMEN
The polyhydroxylated silane network of a sol-gel protected immobilised Saccharomyces cerevisiae against the effects of five organic solvents. The viability of immobilised yeast directly correlated with the logarithm of the partition coefficient of the solvent in an octanol/water two phase system increasing the decimal reduction time (D) and reaching the maximum with octanol, the most hydrophobic solvent assayed. The D value increased from 0.16 min for free yeast to 1.9 and to 22 min for immobilised yeast exposed to ethanol and 1-octanol respectively.