Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw

Background: Oleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources. Results: A total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO4 was used for growth of the yeast, resulting in a yield of 5.17 g L−1 lipids with conversion productivity of 0.06 g L−1 h−1 . Optimization of the levels of yeast extract, peptone, and MgSO4 for maximizing lipid production using Box­Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids. Conclusion: The fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification

Biofilm formation by Rhodococcus equi and putative association with macrolide resistance / Formação de biofilme por Rhodococcus equi e possível associação com resistência a macrolídeos

Rhodococcus equi is a facultative intracellular pathogen, which cause severe pyogranulomatous pneumonia in foals and tuberculosis-like lesions in humans. Its ability to form biofilm was described in strains isolated from chronic diseases associated to treatment failures in humans. This study aimed to verify the biofilm formation by 113 R. equi isolated from equine samples (clinical and fecal) using two different methods (biofilm-culturing with and without additional glucose and epifluorescence microscopy). We also aimed to determine the efficacy of azithromycin, clarithromycin and erythromycin on R. equi in established biofilm. We found 80.5% (26/41) and 63% (58/72) biofilm-positive isolates, in fecal and clinical samples, respectively. The additional glucose increased the biofilm formation by R. equi fecal samples, but not by clinical samples. The antimicrobials tested herein were not able to eradicate R. equi in biofilm even at higher concentrations. This is the first study showing the biofilm formation by R. equi isolated from equine samples. Our findings indicate that R. equi biofilm-producers may be more resistant to the antimicrobials evaluated. Further studies are warranted to test this hypothesis...

Rhodococcus equi é um patógeno intracelular facultativo, o qual causa pneumonia piogranulosa severa em potros e lesões semelhantes à tuberculose em humanos. A sua capacidade de formar biofilme foi descrita em cepas humanas, isoladas a partir de doenças crônicas associadas a falhas de tratamento. Este estudo teve como objetivo verificar a formação de biofilme por 113 cepas de R. equi, isoladas a partir de amostras de equinos (clínicas e fecais), utilizando-se dois diferentes métodos (biofilme em cultura - com e sem adição de glicose - e microscopia de epifluorescência). Além disso, buscou-se determinar a eficácia da azitromicina, claritromicina e eritromicina sobre biofilme consolidado de R. equi. Verificou-se 80,5% (26/41) e 63% dos isolados (58/72) positivos para formação de biofilme, em amostras fecais e clínicas, respectivamente. A adição de glicose amentou a formação de biofilme em amostras fecais, mas não em amostras clínicas. Os antimicrobianos aqui testados não foram capazes de erradicar R. equi em biofilme consolidado, mesmo em concentrações elevadas. Este é o primeiro estudo a demonstrar a formação de biofilme por cepas de R. equi isoladas a partir de amostras de equinos. Os resultados indicam que os isolados de R. equi produtores de biofilme podem ser mais resistentes aos antimicrobianos avaliados. Estudos adicionais são necessários para testar essa hipótese...

Optimization of exopolysaccharides production from a novel strain of Ganoderma lucidum CAU5501 in submerged culture

This study aimed at optimizing the medium of a new Ganoderma lucidum strain CAU5501 to enhance the yield of exopolysaccharides (EPS) and mycelial growth. Firstly, the suitable level of glucose, magnesium, phosphate and C/N ratio was determined by single factor experiment. Subsequently, the optimum concentrations of these medium components were investigated using the orthogonal matrix method. The results indicated that the higher levels of EPS were correlated with the level of cell growth when glucose concentration was studied (data no show). The optimum medium for EPS yield was found to be 70 g/l glucose, 5 C/N ratio, 2.5 g/l KH2PO4, 0.75 g/l MgSO4·7H2O, and for mycelial growth was 50 g/l glucose, 5 C/N ratio, 1.5 g/l KH2PO4, 0.5 g/l MgSO4·7H2O. When cultivated in the obtained optimal media in 3 L shake flask, compared to the basal medium, the EPS yield increased markedly from 1.003 to 1.723 g/l, and the mycelium formation was also markedly improved from 2.028 to 7.235 g/l. Results obtained in this study are beneficial to further study for enhancing the production of Ganoderma lucidum polysaccharides in large scale commercialized production.

Bioconversion of glycerol for bioethanol production using isolated Escherichia coli SS1

Bioconverting glycerol into various valuable products is one of glycerol's promising applications due to its high availability at low cost and the existence of many glycerol-utilizing microorganisms. Bioethanol and biohydrogen, which are types of renewable fuels, are two examples of bioconverted products. The objectives of this study were to evaluate ethanol production from different media by local microorganism isolates and compare the ethanol fermentation profile of the selected strains to use of glucose or glycerol as sole carbon sources. The ethanol fermentations by six isolates were evaluated after a preliminary screening process. Strain named SS1 produced the highest ethanol yield of 1.0 mol: 1.0 mol glycerol and was identified as Escherichia coli SS1 Also, this isolated strain showed a higher affinity to glycerol than glucose for bioethanol production.

Statistical optimisation of cell growth and carotenoid production by Rhodotorula mucilaginosa

Sequential statistical methods were used to maximise carotenoid production by a strain of Rhodotorula mucilaginosa, isolated from the Brazilian ecosystem. Initially, a factorial 2(5-1) experimental design was used, and the variables were pH and the levels of glucose, yeast extract, MgSO4.7H2O and KH2PO4. The nitrogen source (yeast extract) was the most important variable in enhancing carotenoid production; MgSO4.7H2O and KH2PO4 had a negative influence. The initial pH had no significant effect on carotenoid and cell productions. We further investigated the effects of glucose and yeast extract effects, using a second-order central composite design (CCD) to optimise carotenoid production, which was adequately approximated with a full quadratic equation obtained from a two-factor-2-level design. The analysis of quadratic surfaces showed that after 5 days of cultivation at 25ºC, the maximum carotenoid concentration (745 µg l-1) was obtained with 15 g l-1 of yeast extract and 20 g l-1 of glucose. The maximum carotenoid production (152 µg g-1) was obtained with 5 g l-1 yeast extract and 10 g l-1 glucose. Carotenoid formation was more sensitive to changes in yeast extract concentration than to changes in glucose concentration. Maximum cell production was achieved with 15-17 g l-1 of yeast extract and 15-20 g l-1 of glucose.

Transport of jundiá Rhamdia quelen juveniles at different loading densities: water quality and blood parameters

Fish transportation is a common practice on fish farms and is considered to be a stressor that could negatively affect fish health. The objective of this study was to evaluate several physiological responses of stress in jundiá caused by transport at different loading densities. Jundiá juveniles were placed in plastic bags on a mechanical transport simulator for four hours at four different loading densities (75, 150, 250 and 350 g L-1) and then transferred to sixteen 80-L plastic boxes for 96 hours after transport. Water samples were collected before and after transport to measure dissolved oxygen, temperature, pH and ammonia levels. Blood samples were taken at departure and arrival, as well as at 24 and 96 hours after transport to monitor cortisol, glucose, ammonia, chloride and hematocrit levels. Water ammonia levels were found to increase gradually as loading densities increased. Plasma ammonia was higher after transport in fish from all treatments. Compared to initial values, substantial increases in plasma cortisol and ammonia levels were detected mainly in those fish submitted to the highest loading density. Blood glucose appeared to be positively influenced by the increase of transport densities. No statistical differences were observed in any of the other blood parameters. The costs in fish culture, as in other animal production systems, must be minimized and fish producers depend on optimal techniques to ensure better profit. Therefore, based on fish survival and the physiological indicators determined in the present study, especially during recovery, the best density at which to transport jundiá in plastic bags for four hours is about 350 g/L.

O transporte de peixes é uma prática comum em piscicultura e considerado como um agente estressor que causa efeitos negativos na saúde do peixe. O objetivo deste estudo foi avaliar algumas respostas fisiológicas de estresse no jundiá causadas pelo transporte em densidades diferentes. Juvenis de jundiá foram transportados em sacos plásticos num simulador de transporte por quatro horas em diferentes densidades (75, 150, 250 e 350 g L-1) e transferidos para 16 caixas plásticas de 80 L por 96 horas após o transporte. Amostras de água foram coletadas antes e após o transporte para determinações de oxigênio dissolvido, temperatura, pH e amônia. Além dos momentos da saída e da chegada, amostras de sangue foram retiradas 24 e 96 horas após o transporte para monitorar os níveis de cortisol, glicose, amônia, cloreto e hematócrito. A amônia na água aumentou gradualmente acompanhando o aumento das densidades. A amônia plasmática estava elevada após o transporte nos peixes de todos os tratamentos. Comparando com os valores iniciais, aumentos substanciais nos níveis plasmáticos de cortisol e amônia foram registrados principalmente nos peixes submetidos à densidade de transporte mais elevada. Os níveis glicêmicos parecem ter sido influenciados pelo aumento nas densidades de transporte. Não foram registradas diferenças significativas nos demais parâmetros sanguíneos. O custo da criação de peixes, da mesma forma que de outros animais, deve ser minimizado e os produtores dependem de técnicas que permitam lucros maiores. Portanto, com base nos indicadores fisiológicos e na taxa de sobrevivência obtidos no presente estudo, especialmente considerando o período de recuperação, sugere-se que a melhor densidade para o transporte do jundiá em sacos plásticos por quatro horas seja de aproximadamente 350 g/L.

Indice glicêmico de alimentos brasileiros: efeitos do armazenamento sob baixa temperatura (-20ºC) / Glycemic index of Brazilian foods: effect of storage on low temperature (-20ºC)

A extensäo e duraçäo da elevaçäo da glicose sangüínea após uma refeiçäo dependem da velocidade de absorçäo e da velocidade de hidrólise e difusäo dos produtos da hidrólise no intestino delgado. Os alimentos ricos em amido, quando submetidos à cocçäo em água e resfriamento, sofrem gelatinizaçäo e retrogradaçäo. O amido retrogradado representa uma significativa fonte de amido resistente cuja formaçäo, nos alimentos, pode ser um fator colaborador para o aumento de ingestäo de fibra alimentar. O índice glicêmico visa mostrar, indiretamente, como cada alimento se comporta em termos de velocidade de digestäo e absorçäo. A importância de seu estudo está vinculada aos possíveis efeitos fisiológicos e terapêuticos de dietas com índices glicêmicos conhecidos. O presente estudo in vivo (humanos), tem como objetivos: determinar o índice glicêmico de cinco alimentos brasileiros submetidos ao armazenamento sob baixa temperatura (-20ºC), avaliar os fatores desses alimentos que podem influenciar na resposta glicêmica e avaliar a prbabilidade de utilizaçäo de parâmetros alternativos para predizer o índice glicêmico. Os alimentos foram submetidos à cocçäo e armazenamento a -20ºC por 30 dias. Foram elaboradas as curvas glicêmicas de dez indivíduos após a ingestäo destes alimentos, bem como, foram calculados seus índices glicêmicos. Após armazenamento a -20ºC/30 dias o índice glicêmico das leguminosas (feijäo e gräo de bico) reduziu significativamente, o do macarräo ficou inalterado e o da polenta aumentou. A correlaçäo negativa significativa entre índice glicêmico e fibra alimentar serve para orientar sobre a possível resposta glicêmica dos alimentos. O índice de hidrólise e o amido rapidamente digerido (base seca) mostraram-se bons parâmetros para predizer o índice glicêmico dos alimentos