Enhanced microbial biomass and lipid production through co-cultivation of yeast Rhodotorula toruloides and microalga Chaetoceros muelleri

Aims@#The synergistic bio-activity between oleaginous yeast and microalga has been recognized, which would enhance lipid production as biodiesel feedstock. Nevertheless, yeast and microalga require different conditions for optimal growth. In this study, the locally isolated oleaginous yeast Rhodotorula toruloides and microalga Chaetoceros muelleri were co-cultivated to enhance biomass and lipid production.@*Methodology and results@#The growth characteristics of both yeast and microalga monocultures were initially determined prior to optimizing the co-cultivation conditions. The biomass and lipid productivity of the co-culture were investigated and compared to their monocultures. The results showed that R. toruloides grew actively within 3 days while C. muelleri exhibited more prolonged cultivation, up to 21 days. The co-cultivation could be carried out optimally using growth media at pH 6, light intensity of 15,000 lux and yeast/microalga ratio of 1:2, yielding the highest biomass productivity determined at 0.18 g/l/day and lipid production of 17%. The lipid productivity of the co-culture increased by 42% and 75% as compared to monocultures of yeast and microalga, respectively. Furthermore, the biomass productivity was also higher than the monoculture, about 1.2-fold for the yeast and 13-fold for the microalga.@*Conclusion, significance and impact of study@#The findings revealed that co-cultivation of yeast and microalga is a viable technique for long-term microbial oil production.

Enhancement of harvesting efficiency and polyunsaturated fatty acid-rich lipid production of Aurantiochytrium sp. SW1 by co-cultivation with oleaginous fungus Cunninghamella bainieri 2A1

Aims@#Thraustochytrids have been shown to be excellent lipid producers due to their ability to accumulate over 50% lipid (g/g biomass) containing up to 50% docosahexaenoic acid (DHA). However, efficient and cost-effective cell recovery of lipid-rich biomass has become a significant challenge at the industrial scale. In this study, we attempted to enhance the harvesting efficiency (HE) and the DHA content of Aurantiochytrium sp. through co-cultivation with a γ-linolenic acid (GLA)-producing oleaginous filamentous fungus, Cunninghamella bainieri 2A1.@*Methodology and results@#A 72 h old C. bainieri 2A1 culture in the form of loose mycelia or pellets of various sizes was added into 72 h old Aurantiochytrium sp. cultures and further incubated for 48 h. The HE of Aurantiochytrium sp. was then determined by comparing the remaining OD values of the supernatant with and without minimal centrifugation at 4000× g. Results showed that 63.23% of HE was achieved without centrifugation from co-cultivation with dispersed mycelia. Higher HE between 96.71-99.55% was achieved when centrifugation was implemented, with the highest value resulting from co-cultivation with dispersed mycelia. These are higher than HE of centrifuged control cultures (80%) consisting of Aurantiochytrium sp. monocultures, suggesting that co-cultivation with C. bainieri 2A1 facilitates the recovery of Aurantiochytrium sp. cells. Moreover, the co-cultivation also resulted in a 28% increase in DHA compared to non-optimized cultures.@*Conclusion, significance and impact of study@#This study provides the first evidence of enhancement in harvesting and DHA content of oleaginous thraustochytrids that could be achieved through co-cultivation with oleaginous fungi.

Improved protease activity of Pixian broad bean paste with cocultivation of Aspergillus oryzae QM-6 and Aspergillus niger QH-3

BACKGROUND: The preparation of broad bean koji is a key process in the production of Pixian broad bean paste (PBP). Protease is essential for the degradation of proteins during PBP fermentation. To obtain broad bean koji with high protease activity using the cocultivated strains of Aspergillus oryzae QM-6 (A. oryzae QM-6) and Aspergillus niger QH-3 (A. niger QH-3), the optimization of acid and neutral protease activities was carried out using Box­Behnken design with response surface methodology (RSM). RESULTS: The optimum conditions were found to be as follows: inoculation proportion (X1), 3:1 (A. oryzae QM-6: A. niger QH-3, w/w); culture temperature (X2), 33°C; inoculum size (X3), 0.5% (w/w); incubation time (X4), 5 d. The acid and neutral protease activities were 605.2 ± 12.4 U/g and 1582.9 ± 23.7 U/g, respectively, which were in good agreement with the predicted values. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles revealed that the broad bean koji extracellular proteins in the case of cocultivation were richer compared to those in the case of A. oryzae QM-6 or A. niger QH-3 strain only. In addition, the free amino acids (FAAs) in the fermentation product were 55% higher in the cocultivation process than in that involving only A. oryzae QM-6, further confirming the diversity of proteases in the fermentation products. CONCLUSIONS: The optimal conditions of koji-making in PBP were obtained using RSM. The cocultivation of A. oryzae and A. niger increases the overall enzyme activities in the culture medium and the FAAs content, which would thus have potential application in the PBP industry.

In vitro establishment of Comanthera curralensis , "sempre viva" native of Chapada Diamantina - Bahia / Estabelecimento in vitro de Comanthera curralensis, "sempre viva", nativa da Chapada Diamantina - Bahia

ABSTRACT: The goal of the present study was to evaluate the germination, initial growth, and in vitro co-cultivation of Comanthera curralensis Moldenke, a "sempre viva" native of the Chapada Diamantina state of Bahia. Full strength (MS) and half-strength MS (MS1/2) growth media supplemented with two different sucrose concentrations (15 and 30g L-1) were tested for germination and initial plant growth. Three different plant densities were tested by in vitro culture (8, 10 and 12 plants per container). MS1/2 medium with 15g L-1 sucrose resulted in a higher percentage of germination and plant growth for the in vitro establishment of C. curralensis. The use of 12 plants per container is indicated for cost reduction in C. curralensis in vitro production.

RESUMO: Este trabalho teve como objetivo avaliar a germinação, o crescimento inicial e o co-cultivo in vitro de Comanthera curralensis Moldenke, uma "sempre viva" nativa da Chapada Diamantina-BA. Para germinação e crescimento inicial, foram testados os meios de cultura MS completo e MS1/2 suplementados com duas concentrações de sacarose (15 e 30gL-1); no cultivo in vitro, foram testadas três quantidades de plantas por recipiente (8,10 e 12). A utilização do meio MS1/2 com 15gL-1 de sacarose proporcionou maiores porcentagem de germinação crescimento das plantas no estabelecimento in vitro de C. curralensis , e o uso de 12 plantas por recipiente é indicado para a redução de custos na produção in vitro da espécie.

Exploration of teaching for orthopedic postgraduates / 中华医学教育探索杂志

To improve higher training quality and capacity of orthopedic postgraduates,early contact education,problem-base learning combined with co-supervisor with radiologists were engaged for orthopedic postgraduates since 2008.Effect of the practice was assessed by postgraduates one year later.Investigation revealed that practice aroused learning enthusiasm and initiative,promoted comprehensive understanding of orthopedic knowledge,set up social responsibility,and constructed innovative thinking.

Quantitative transient GUS expression in J-104 rice calli through manipulation of in vitro culture conditions

This paper purposes suitable conditions for callus induction and co-cultivation with Agrobacterium tumefaciens of J-104 rice cultivar. It was evaluated the effect of different concentrations of 2.4-D and agar, and the inclusion of L-proline and L-glutamine in callus culture medium. The use of 2.5 mg/L 2.4-D and 0.8% agar allowed the highest percentage of embryogenic calli. Callus formation was improved considerably with 500 mg/L of L-proline and L-glutamine in the culture medium. Different factors were studied throughout co-cultivation of calli with A. tumefaciens: inoculation time, co-cultivation temperature, concentration of acetosyringone and co-cultivation period. Transient GUS expression was quantified by fluorometry in all co-cultivated calli. The best results were obtained with the following conditions: 10 min as inoculation time, 100µM acetosyringone in co-cultivation medium, temperature of 20ºC, and 3 days as co-cultivation period.

Se describen las condiciones óptimas para la callogénesis y cocultivo de callos con Agrobacterium tume-faciens de la variedad de arroz J-104. Se determinó el efecto de diferentes concentraciones de 2.4-D, agar y de L-prolina y L-glutamina en el medio de cultivo de callos. El uso de 2,5 mg/L de 2.4-D y 0,8% de agar permitió lograr el porcentaje más alto de callos embriogénicos. La formación de callos fue mejorada considerablemente con la adición de 500 mg/L de L-prolina e igual concentración de L-glutamina en el medio de cultivo. Se estudiaron diferentes factores en el cocultivo de los callos con A. tumefaciens: tiempo de inoculación, concentración de acetosiringona, temperatura y tiempo de cocultivo. Para comparar el efecto de cada factor sobre la expresión GUS se cuantificó la actividad transitoria mediante fluorimetría. Los valores más altos de actividad fluorimétrica fueron obtenidos con las siguientes condiciones: 10 min de inoculación, 100µM de acetosiringona en el medio de cocultivo y 3 días de cocultivo a 20 ºC.