Antonio Cobo

Characterization of lactic acid bacteria from naturally-fermented Manzanilla Aloreña green table olives.

Manzanilla Aloreña (or Aloreña) table olives are naturally fermented traditional green olives with a denomination of protection (DOP). The aim of this study was to search for lactic acid bacteria (LAB) with technological properties of interest for possible inclusion in a starter or protective culture preparation or also as probiotics. A collection of 144 LAB obtained from Aloreña green table olives naturally-fermented by four small-medium enterprises (SMEs) from Málaga (Spain), including lactobacilli (81.94%), leuconostocs (10.42%) and pediococci (7.64%) were studied. REP-PCR clustering and further identification of strains by sequencing of phes and rpo genes revealed that all lactobacilli from the different SMEs were Lactobacillus pentosus. Pediococci were identified as Pediococcus parvulus (SME1) and leuconostocs as Leuconostoc pseudomesenteroides (SME1 and SME4). Genotyping revealed that strains were not clonally related and exhibited a considerable degree of genomic diversity specially for lactobacilli and also for leuconostocs. Some strains exhibit useful technological properties such as production of antimicrobial substances active against pathogenic bacteria such as Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Streptococcus mutans and Salmonella enterica, utilization of raffinose and stachyose, production of bile salt hydrolase, phytase and haeme-dependent catalase activities, growth at 10 °C and in the presence of 6.5% NaCl, good acidifying capacity and also resistance to freezing. However, none of the isolates showed protease or amylase activity, and also did not exhibit biogenic amine production from histidine, ornithine, cysteine or tyrosine. On the basis of data obtained, selected strains with potential traits were tested for their survival at low pH and their tolerance to bile salts, and the survival capacity demonstrated by some of the analysed strains are encouraging to further study their potential as probiotics.

Effect of virgin and refined olive oil consumption on gut microbiota. Comparison to butter

There is increasing evidence of the health benefits of olive oil consumption in the diet. Some authors have studied the effect of high fat/high calorie diets and have detected changes on the microbiota. However, these studies are mainly based on saturated fats. Here we present a study on the specific effect on gut bacterial populations of extra virgin olive oil, rich in monounsaturated fatty acids and phenolic compounds, in comparison to refined olive oil, rich in monounsaturated fatty acids but low in phenolic compounds, and to butter, rich in saturated fatty acids and cholesterol. Four groups of animals were studied: one group of mice received a standard chow diet, and the other received three high fat diets, rich in extra virgin olive oil, refined olive oil or butter. Evolution of symbiont population in feces was studied using culture-dependent and culture-independent methods. In the latter, the V3 region of 16S rDNA was amplified and separated by denaturing gradient gel electrophoresis; followed by sequencing of the most representative bands. Culture-dependent studies and comparison of the different DGGE profiles throughout the experiment demonstrated that different dietary fats had different effects on gut microbial composition. Butter-induced changes in the microbial counts resembled those previously described in obese individuals. Interestingly, a different behavior between extra virgin and refined olive oil was also observed, extra virgin olive oil being most different from butter. To our knowledge, no studies have analyzed gut microbiota depending on diets with different fatty acid saturations including different types of olive oil. This may offer new data supporting the benefits for health of extra virgin olive oil, so important in the Mediterranean diet.

Influence of a diet enriched with virgin olive oil or butter on mouse gut microbiota and its correlation to physiological and biochemical parameters related to metabolic syndrome

The type of fat in the diet determinates the characteristics of gut microbiota, exerting a major role in the development of metabolic syndrome. We hypothesize that a diet enriched with extra virgin olive oil (EVOO) has a distinctive effect on the intestinal microbiome in comparison with an enriched butter diet (BT) and this effect is related to the physiological benefits exerted by EVOO. Swiss Webster mice were fed standard (SD) or two high fat diets enriched with EVOO or butter. Hormonal, physiological and metabolic parameters were evaluated. At the end of the feeding period, DNA was extracted from faeces and the 16S rRNA genes were pyrosequenced. Among the main significant differences found, BT triggered the highest values of systolic blood pressure, correlating positively with the percentage of Desulfovibrio sequences in faeces, which in turn showed significantly higher values in BT than in EVOO. EVOO had the lowest values of plasmatic insulin, correlating inversely with Desulfovibrio, and had the lowest plasmatic values of leptin which correlated inversely with Sutterellaceae, Marispirillum and Mucilaginibacter dageonensis, the three showing significantly higher percentages in EVOO. The lowest total cholesterol levels in plasma were detected in SD, correlating positively with Prevotella and Fusicatenibacter, both taxa with significantly greater presence in SD. These results may be indicative of a link between specific diets, certain physiological parameters and the prevalence of some taxa, supporting the possibility that in some of the proposed effects of virgin olive oil the modulation of intestinal microbiota could be involved.

Natural Antimicrobials for Biopreservation of Sprouts

In recent years there has been an increase in consumers demands for mungbean, alfalfa, soybean, radish and other seed sprouts (Rosas and Escartin, 2000) that are usually eaten raw in salads or in sandwiches. Seed sprouts have been part of the human diet since old times in countries such as Japan where they are widely consumed. Tthe interest in consuming fresh green sprouts has extended all over the world because they are considered to provide health benefits (Rosas and Escartin, 2000). A great variety of seed sprouts can be found at present in the market, such as adzuki bean (Phaseolus angularis), alfalfa (Medicago sativa), broccoli (Brassica oleracea convar. botrytis), cress (Lepidium sativum), lentil (Lens culinaris), mung bean (Phaseolus aureus), soybean (Glycine max), white mustard (Sinapis alba), green and yellow pea (Pisum sativum), onion (Allium cepa), radish (Raphanus sativus), rice (Oryza sativa L.), rye (Secale cereale), sesame (Sesamum indicum), sunflower (Helianthus annuus) and wheat (Triticum aestivum), although the most popular are alfalfa, soybeans, mung beans and raddish (Taormina et al., 1999). Seed sprouts are usually eaten raw in salads or in sandwiches, and concerns for the safety of these raw foods have increased lately. Sprouts are grown from seeds placed in environmentally controlled, hydroponic conditions and incubated in warm, moist, nutrient-rich conditions, which are ideal environments for microbial growth. The seeds usually carry microbial loads comprised between 3 and 6 log CFU/g, including pseudomonads and enterobacteriaceae as main components (Andrews et al., 1982; Prokopowich and Blank, 1991; Robertson et al., 2002; Splittstoesser et al., 1983). The bacterial load increases rapidly during the sprouting process, reaching from 6 to 8 log CFU/g after two days in one study (Fu et al., 2001) and between 7.8 and 8.8 in another (Weiss et al., 2007). Other reports have indicated final counts of up to 8-9 log CFU/g in commercial sprouts (Patterson and Woodburn, 1980; Prokopowich and Blank, 1991). In addition, the pathogenic bacteria can survive on sprouts through the typical refrigerated shelf life of the products (Harris et al., 2003). Recent studies indicate that pathogenic bacteria can survive both on and in plant tissues (Lynch et al., 2009). For example, when alfalfa seeds contaminated with Escherichia coli O157 or with Salmonella are sprouted, the bacteria enter the growing sprout, and appear throughout the deep tissues of the young plants (Itoh et al.,

Changes in Gut Microbiota Linked to a Reduction in Systolic Blood Pressure in Spontaneously Hypertensive Rats Fed an Extra Virgin Olive Oil-Enriched Diet

Fat type in diet is responsible for specific changes in gut microbiota (GM). Extra virgin olive oil (EVOO) has been shown to be beneficial for blood pressure and to produce effects on GM. To analyze the cause-effect relationship between intestinal microbial changes and blood pressure, we studied the effect of EVOO on fecal microbiota and systolic blood pressure (SBP) levels in spontaneously hypertensive rats (SHR). SHR were fed either an enriched EVOO diet or a standard diet for a period of 12 weeks. At the end of the experimental period, the microbial profiles in the feces were studied in both groups by using PCR-denaturing gradient gel electrophoresis. Real-time PCR was used to quantify the selected bacterial groups. The results demonstrated significant differences when using Lactobacillus (p<0.05), clostridia XIV (p<0.01) and universal (p<0.05) primers. A significant (r=−0.475; p=0.04) inverse correlation between the abundance of clostridia XIV and SBP, which depends on the type of diet, was also observed. Finally, the results suggested an increase in the microbial diversity of the feces of the animals fed the EVOO diet. These results strongly connect the pattern of GM in SHR fed a diet enriched with EVOO to the lower levels of SBP observed in these animals at the end of the feeding period.