In this work, biosurfactant production by a Pseudomonas aeruginosa strain was optimized using low-cost substrates. The highest biosurfactant production (3.2 g/l) was obtained using a culture medium containing corn steep liquor (10% (v/v)) and molasses (10% (w/v)). The biosurfactant reduced the surface tension of water up to 30 mN/m, and exhibited a high emulsifying activity (E24=60%), with a critical micelle concentration as low as 50 mg/l. The biosurfactant produced in this alternative medium was characterized as a mixture of eight different rhamnolipid congeners, being the most abundant the mono-rhamnolipid Rha-C10-C10. However, using LB medium, nine different rhamnolipid congeners were identified, being the most abundant the di-rhamnolipid Rha-Rha-C10-C10. The rhamnolipid mixture produced in the alternative medium exhibited a better performance in removing oil from contaminated sand when compared with two chemical surfactants, suggesting its potential use as an alternative to traditional chemical surfactants in enhanced oil recovery or bioremediation.

RESUMO -Objetivou-se avaliar a eficácia de aditivos químicos e inoculantes bacterianos na inibição da produção de etanol, na diminuição das perdas de MS e na melhoria da digestibilidade in vitro de silagens de cana-de-açúcar. Foram testados os seguintes tratamentos (doses com base na matéria natural): sem aditivos -controle; UR -uréia (0,5; 1,0; 1,5%); NaOH -hidróxido de sódio (1,0; 2,0; 3,0%); PROP -propionato de cálcio (0,05; 0,1; 0,2%); BENZ -benzoato de sódio (0,05; 0,1; 0,2%); SORB -sorbato de potássio (0,015; 0,03; 0,045%); PLA -Lactobacillus plantarum (1 x 10 6 ufc/g); BUCH -Lactobacillus buchneri (3,64 x 10 5 ufc/g); PLA/UR 0,5% -L. plantarum combinado com 0,5% de uréia; PLA/UR 1,0% -L. plantarum combinado com 1,0% de uréia. A ensilagem foi realizada em baldes plásticos de 20 L adaptados com válvulas para eliminação de gases e dispositivo para coleta de efluentes. Os dados foram coletados aos 90 e aos 180 dias após a ensilagem. Nenhum dos aditivos foi capaz de reduzir a concentração de etanol nas silagens. Os tratamentos PROP 0,1% e PLA causaram aumento no teor de álcool em relação à silagem controle (4,8 e 12,5% vs 3,8% da MS, respectivamente). Os tratamentos UR, NaOH, SORB-0,03%, BUCH, PLA/UR 0,5% e PLA/UR 1,0% reduziram a perda total de MS. As silagens tratadas com uréia, hidróxido de sódio, benzoato de sódio e sorbato de potássio 0,045% apresentaram maior digestibilidade in vitro da MS em comparação à silagem controle. and 12.5% vs 3.8% in DM, respectively). The treatments UR, NaOH, SORB-0.03%, BUCH, PLA/UR-0.5% and PLA/UR-1.0%reduced total DM losses. Silages treated with UR, NaOH, BENZ and SORB-0,045% had higher in vitro DM digestibility than the control silage.

In this work, biosurfactant production by Bacillus subtilis #573 was evaluated using corn steep liquor (CSL) as culture medium. The best results were obtained in a culture medium consisting of 10% (v/v) of CSL, with a biosurfactant production of about 1.3 g/l. To the best of our knowledge, this is the first report describing biosurfactant production by B. subtilis using CSL as culture medium. Subsequently, the effect of different metals (iron, manganese, and magnesium) on biosurfactant production was evaluated using the medium CSL 10%. It was found that for all the metals tested, the biosurfactant production was increased (up to 4.1, 4.4, and 3.5 g/l for iron, manganese, and magnesium, respectively). When the culture medium was supplemented with the optimum concentration of the three metals simultaneously, the biosurfactant production was increased up to 4.8 g/l. Furthermore, the biosurfactant exhibited a good performance in oil recovery assays when compared with chemical surfactants, which suggests its possible application in microbial enhanced oil recovery or bioremediation.

Lactic acid bacteria (LAB) are a promising solution to reduce exposure to dietary mycotoxins because of the unique mycotoxin decontaminating characteristic of some LAB. Ochratoxin A (OTA) is one of the most prominent mycotoxins found in agricultural commodities. The present work reports on the ability of Pediococcus parvulus strains that were isolated from Douro wines that spontaneously underwent malolactic fermentation to detoxify OTA. These strains were identified and characterised using a polyphasic approach that employed both phenotypic and genotypic methods. When cultivated on OTA-supplemented MRS media, OTA was biodegraded into OTα by certain P. parvulus strains. The presence of OTα was confirmed using LC-MS/MS. The conversion of OTA into OTα indicates that the OTA amide bond was hydrolysed by a putative peptidase. The rate of OTA biodegradation was found to be dependent on the inoculum size and on the incubation temperature. Adsorption assays with dead P. parvulus cells showed that approximately 1.3%±1.0 of the OTA was adsorbed onto cells wall, which excludes this mechanism in the elimination of OTA by strains that degrades OTA. Under optimum conditions, 50% and 90% of OTA were degraded in 6 and 19h, respectively. Other LAB strains that belonged to different species were tested but did not degrade OTA. OTA biodegradation by P. parvulus UTAD 473 was observed in grape must. Because some P. parvulus strains have relevant probiotic properties, the strains that were identified could be particularly relevant to food and feed applications to counteract the toxic effects of OTA.

In this work, oil mill wastewater (OMW), a residue generated during olive oil extraction, was evaluated as an inducer of rhamnolipid production. Using a medium containing as sole ingredients corn steep liquor (10%, v/v), sugarcane molasses (10%, w/v) and OMW (25%, v/v), Pseudomonas aeruginosa #112 produced 4.5 and 5.1g of rhamnolipid per liter in flasks and reactor, respectively, with critical micelle concentrations as low as 13mg/l. Furthermore, in the medium supplemented with OMW, a higher proportion of more hydrophobic rhamnolipid congeners was observed comparing with the same medium without OMW. OMW is a hazardous waste which disposal represents a serious environmental problem; therefore, its valorization as a substrate for the production of added-value compounds such as rhamnolipids is of great interest. This is the first report of rhamnolipid production using a mixture of these three agro-industrial by-products, which can be useful for the sustainable production of rhamnolipids.

-The objective of this work was to evaluate the performance of heifers fed sugarcane silages produced with and without additives. Thirty-two Holstein heifers were randomly assigned, in a block design, to evaluate rations (46% silage; 54% concentrate; 12% crude protein) containing silages treated with (fresh basis) urea (0.5%), sodium benzoate (0.1%) or Lactobacillus buchneri (3.64x10 5 cfu g -1 ). Inoculation with L. buchneri improved daily gain (1.24 vs. 0.94 kg day -1 ), and the addition of benzoate resulted in better feed conversion (7.6 vs. 9.4 kg of dry matter per kg of live weight), in relation to the untreated silage (control). Treatments did not affect dry matter intake (mean of 2.19% of live weight). Rations containing silages treated with benzoate or L. buchneri showed lower cost per kg of weight gain. Treatment with urea did not improve animal performance, but the cost per kg of weight gain was lower than that of the control ration.Index terms: additive, inoculant, nutritional value, weight gain. Desempenho de novilhas Holandesas alimentadas com silagens de cana-de-açúcar tratadas com uréia, benzoato de sódio ou Lactobacillus buchneriResumo -O objetivo deste trabalho foi avaliar a performance de novilhas alimentadas com silagens de cana-deaçúcar tratadas com aditivos. Trinta e duas novilhas Holandesas foram aleatoriamente distribuídas em um delineamento em blocos, para avaliar rações (46% silagem; 54% concentrado; 12% proteína bruta) contendo silagem tratada com (base matéria verde) uréia (0,5%), benzoato de sódio (0,1%) ou Lactobacillus buchneri (3,64x10 5 ufc g -1 ). A inoculação de L. buchneri melhorou o ganho diário (1,24 vs. 0,94 kg dia -1 ) e a adição de benzoato melhorou a conversão alimentar (7,6 vs. 9,4 kg de matéria seca por kg de peso vivo), relativamente ao controle (silagem não tratada). Os tratamentos não afetaram o consumo de matéria seca (2,19% do peso vivo). As rações com silagens tratadas com benzoato ou L. buchneri mostraram menor custo por kg de ganho de peso. O tratamento com uréia não melhorou o desempenho animal, mas o custo por kg de ganho de peso foi menor do que na dieta controle.Termos para indexação: aditivo, inoculante, valor nutritivo, ganho de peso.

-The effect of nitrogen (N) fertilization (0, 50, 100 and 200 kg N ha -1 ) on forage yield and morphogenesis of Axonopus aureus was evaluated in the savannas of Roraima State, Brazil. The experimental design was in randomized blocks with three replicates. The grass showed high responsiveness to N fertilization. Dry weight (DW) yield, morphogenetic and structural traits and forage quality were positively affected by N fertilization. The effects of N fertilization on DW yield, N content, leaf appearance rate, leaf elongation rate, number of live leaves/tiller, final leaf length and leaf area index were quadratic and maximum values were estimated with application of 168.8 (2,181 kg ha -1 ); 124.8 (21.1 g/kg); 158.5 (0.163 leaf/day per tiller); 172.3 (2.75 cm/tiller per day); 155.5 (17.23 cm); 185.5 (7.55 leaves/tiller) and 185.3 (2.22) kg N ha -1 , respectively. Tiller population density and leaf senescence rate are directly proportional to increase in N rates, and the opposite occurs for N utilization efficiency and apparent N recovery.

In this work, the antifungal activity of rhamnolipids produced by Pseudomonas aeruginosa #112 was evaluated against Aspergillus niger MUM 92.13 and Aspergillus carbonarius MUM 05.18. It was demonstrated that the di-rhamnolipid congeners were responsible for the antifungal activity exhibited by the crude rhamnolipid mixture, whereas mono-rhamnolipids showed a weak inhibitory activity. Furthermore, in the presence of NaCl (from 375 mM to 875 mM), the antifungal activity of the crude rhamnolipid mixture and the purified di-rhamnolipids was considerably increased. Dynamic Light Scattering studies showed that the size of the structures formed by the rhamnolipids increased as the NaCl concentration increased, being this effect more pronounced in the case of di-rhamnolipids. These results were confirmed by Confocal Scanning Laser Microscopy, which revealed the formation of giant vesicle-like structures (in the µm range) by self-assembling of the crude rhamnolipid mixture in the presence of 875 mM NaCl. In the case of the purified mono- and di-rhamnolipids, spherical structures (also in the µm range) were observed at the same conditions. The results herein obtained demonstrated a direct relationship between the rhamnolipids antifungal activity and their aggregation behaviour, opening the possibility to improve their biological activities for application in different fields.