Baltasar Mayo Perez | University of Oviedo (original) (raw)

Papers by Baltasar Mayo Perez

Avances En Microbiologia De Los Alimentos 2012 Isbn 978 84 695 4093 0 Pags 327 328, 2012

Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 2010

Résumé/Abstract Concern for antibiotic resistance carriage in beneficial and commensal microorgan... more Résumé/Abstract Concern for antibiotic resistance carriage in beneficial and commensal microorganisms involved in feed and food fermentations or included in foods as probiotics is based on the possibility of the genetic resistance determinants to be transferred from ...

Journal of bacteriology, 1997

Two cold shock genes, cspL and cspP, have been cloned from two Lactobacillus plantarum strains. T... more Two cold shock genes, cspL and cspP, have been cloned from two Lactobacillus plantarum strains. These genes, which are nonallelic, were present in all strains tested. The genes encode 66-amino-acid polypeptides related to each other and to the cold shock Csp family. Transcription of cspP rendered a single mRNA, while two cspL mRNAs were found with common 5' ends. The amounts of these transcripts increased moderately upon exposure of the cultures to cold.

The aim of this study was to identify numerically dominant cultivable lactobacilli species in the... more The aim of this study was to identify numerically dominant cultivable lactobacilli species in the feces of healthy adults. Ten individuals from Asturias, northern Spain, were chosen. Bacterial colonies grown under anoxic conditions on MRS with cysteine were microscopically examined for lactobacilli. Isolates were subsequently grouped based on the analysis of their carbohydrate fermentation profiles and then identified by partial amplification, sequencing, and comparison of their 16S rRNA gene sequences. Lactobacilli varied from undetectable levels in three subjects (<10 5 CFU/g feces) to around 10 9 CFU/g feces. Among the 71 isolates obtained from seven individuals, 12 Lactobacillus species were identified. High interindividual variation was observed in terms of total numbers, number of species, and dominant species. Lactobacillus paracasei was found in four of the seven individuals; L. gasseri, L. delbrueckii, and L. plantarum in three. Phenotyping showed that only one strain per species was in the majority in each individual.

Research in Microbiology, 2009

Genome announcements, Jan 23, 2014

We here report a 2,801,031-bp annotated draft assembly for the Lactococcus lactis subsp. cremoris... more We here report a 2,801,031-bp annotated draft assembly for the Lactococcus lactis subsp. cremoris GE2-14 genome. This dairy strain produces the biogenic amine putrescine. This sequence may help identify the mechanisms regulating putrescine biosynthesis and throw light on ways to reduce its presence in fermented foods.

Plasmid, 2000

The complete sequence of the 10.9-kbp bacteriocinogenic plasmid pBL1 from Lactococcus lactis subs... more The complete sequence of the 10.9-kbp bacteriocinogenic plasmid pBL1 from Lactococcus lactis subsp. lactis IPLA 972 has been determined. Thirteen ORFs were encountered, of which 5 were incomplete. pBL1 proved to be a narrow-host-range plasmid which replicates neither in Bacilus subtilis nor in Lactobacillus spp. The structural organization of the pBL1 replication region was highly similar to other well-known theta-replicating plasmids of lactococci, at both the untranslated (the replication origin) and the translated (repB and orfX) sequences. As in other plasmids, the product of orfX was not necessary for plasmid replication. However, it was shown to be involved in plasmid stability. Three genes organized in an operon-like structure encompassed, most likely, the bacteriocin-encoding region. Upstream of the origin of replication a nicking site (oriT) was found. This oriT sequence proved to be functional by mobilization of plasmids wearing it. One complete and several partial IS elements were identified on pBL1.

Microbial Ecology, 2013

Stomach mucosa biopsies and gastric juices samples of 12 healthy persons were analysed by culturi... more Stomach mucosa biopsies and gastric juices samples of 12 healthy persons were analysed by culturing in selective-and non-selective-rich media. Microbial DNA from four mucosal samples was also amplified by nested PCR using universal bacterial primers, and the 16S rDNA amplicons pyrosequenced. The total number of cultivable microorganisms recovered from the samples ranged from 10 2 to 10 4 cfu/g or ml. The isolates were identified at the species level by PCR amplification and sequencing of the 16S rDNA. Isolates belonged mainly to four genera; Propionibacterium, Lactobacillus, Streptococcus and Staphylococcus. A total of 15,622 high-quality 16S rDNA sequence reads were obtained by pyrosequencing from the four mucosal samples. Sequence analysis grouped the reads into 59 families and 69 genera, revealing wide bacterial diversity. Considerable differences in the composition of the gastric microbiota were observed among the subjects, although in all samples the most abundant operational taxonomic units belonged to Streptococcus, Propionibacterium and Lactobacillus. Comparison of the stomach microbiota with that present in other parts of the human gastrointestinal tract revealed distinctive microbial communities. This is the first study in which a combination of culture and cultureindependent techniques has been used to explore the bacterial diversity of the human stomach.

International Journal of Antimicrobial Agents, 2007

RFLP and DNA sequencing of PCR products showed that a Lactobacillus rhamnosus strain of human ori... more RFLP and DNA sequencing of PCR products showed that a Lactobacillus rhamnosus strain of human origin resistant to macrolides, from which no resistance determinants have been detected by specific PCR and microarray screening, contained a heterozygous A-to-G transition mutation at position 2058 (Escherichia coli numbering)

Food Research International, 2004

A selection of commercial fermented milks was evaluated for the presence and viability of probiot... more A selection of commercial fermented milks was evaluated for the presence and viability of probiotic lactobacilli and bifidobacteria. Counts of Lactobacillus spp. always remained higher than 10 5 CFU ml À1 , whereas the population of Bifidobacterium spp. decreased below this level in two products. All the probiotics announced on the label were present in commercial products, yet in two fermented milks one additional group of microorganisms was also found. The yogurt microorganism Streptococcus thermophilus was present in all cases, whereas Lactobacillus delbrueckii ssp. bulgaricus was only detected in two products. Bifidobacterium was the most frequently isolated group, all commercial strains being identified as Bifidobacterium animalis/Bifidobacterium lactis by analysis of partial sequences of the 16 rRNA gene. The same technique allowed the identification of members of Lactobacillus casei (species Lactobacillus casei/Lactobacillus paracasei/Lactobacillus zeae) and Lactobacillus acidophilus (species L. acidophilus sensu stricto and Lactobacillus johnsonii). The analysis of macrorrestriction profiles by pulsed-field gel electrophoresis evidenced the reduced genetic variability existing among commercial Lactobacillus and Bifidobacterium strains. The combined use of macrorrestriction analysis and carbohydrate fermentation profiles enhanced the discriminatory power of the first technique for strains differentiation. None commercial Bifidobacterium strain presented the harmful b-glucuronidase activity whereas all of them displayed b-galactosidase, a-glucosidase and a-galactosidase activity.

Int. J. Probiotics Prebiotics, 2008

European Food Research and Technology, 2009

This paper reports on the diversity and dynamics of the dominant microbial populations during 23 ... more This paper reports on the diversity and dynamics of the dominant microbial populations during 23 manufacturing and ripening of Lighvan, a traditional, starter-free Iranian cheese made from raw ewe's and 24 goat's milk, as determined by culturing and PCR-DGGE. Similar dominant populations, composed of Lactococcus lactis and Lactobacillus spp. strains, were found by both techniques. However, discrepancies 26 regarding the identity of these Lactobacillus species were encountered. Lactobacillus curvatus and 27 Lactobacillus sakei proved to be dominant by PCR-DGGE in milk and 4-and 13 week-old cheese samples; 28 however, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus 29 paracasei were the majority cultivable organisms. RAPD typing of lactobacilli isolates showed wide 30 genetic diversity among the different species. Moreover, species and strains evolve over manufacturing and 31 ripening. L. brevis and L. paraplantarum were dominant in milk but were replaced by L. plantarum and L. 32 paracasei strains as ripening progressed. 33 34 1. Introduction 35 Lighvan cheese is a semi-hard, starter-free, traditional Iranian cheese from the mountainous area of 36 Lighvan in the Province of Azerbaijan, Iran, made from a mixture of raw ewe's and goat's milk. The 37 manufacture of Lighvan cheese involves coagulation of evening and morning milk with lamb rennet at 28-38 32 ºC (depending on the season). The coagulum is cut into walnut-size pieces that are then transferred to 39 rectangular-shaped bags and piled up for whey drainage. The resulting curd mass is then cut into 25×25×25 40 cm 3 cubes and placed in a 22% brine flow for 6 h. After removal, the curd cubes are kept in a basin for 3-5 41 days, in which whey drainage continues. During this period the cubes are turned upside down between 9 42 and 15 times. Finally, they are packed in 10-12% brine. Ripening takes place in deep-natural or man-made 43 caves for 3-4 months at an average temperature of 10-12 ºC. 44 Despite the popularity of Lighvan cheese and its ever increasing consumption figures, its chemical 45 composition has been little studied. Even less is known about the microbial communities involved in its 46 manufacture and ripening; only the dominant bacterial genera of mature cheeses have been reported [1, 2]. 47 Knowledge in this area is of particular interest since the typical sensorial properties of traditional cheeses 48 rely on the complex biochemical processes driven by the indigenous microbiota [3] (as well as on the 49 Page 2 of 20 http://mc.manuscriptcentral.com/efrt European Food Research and Technology 65 population dynamics over cheese manufacture and ripening [17-21]. In some cases, however, a 66 combination of culturing and molecular techniques is preferred since complementary results are obtained 67 [22, 23]. In addition, culturing allows the isolation, identification and selection of starter and adjunct 68 cultures. 69 This paper reports the basic chemical characteristics of Lighvan cheese during manufacture and 70 ripening, as well as a preliminary inspection of the dominant microbial communities as determined by 71 DGGE. In addition, the Lactobacillus species in milk, curd and cheese at different stages of ripening 72 (lactobacilli were the majority species throughout ripening) were identified by phenotypic and molecular 73 methods. The characterization of these lactobacillus strains would be of much help in the design of specific 74 starter cultures for the production of standardized Lighvan cheese.

European Food Research and Technology, 2012

Strong bacteriocins, or bacteriocins with a wide range of activity against pathogens and spoilage... more Strong bacteriocins, or bacteriocins with a wide range of activity against pathogens and spoilage microorganisms, are actively sought for use as natural food preservatives. This work reports the inhibitory activity of 96 enterococcal isolates from two Iranian, raw milk cheeses against Wve indicator organisms (including Listeria innocua). Forty-eight isolates inhibited at least one indicator in spot agar assays. Of these, 20 isolates corresponding to 15 diVerent strains were shown to produce bacteriocinlike substances in liquid cultures. PCR analysis revealed the genes coding for enterocins (enterococcal bacteriocins) A, B, P or X, or their combinations, in all but one of these 15 strains. In addition, the gene coding for enterocin 31 was detected in two strains. No ampliWcation was obtained in one strain when using speciWc primers for all 13 bacteriocin genes sought. Three diVerent enterocin genes were identi-Wed in most strains and four in one strain. Although the concomitant production of bacteriocins is still to be veri-Wed, producers of multiple enterocins could be of great technological potential as protective cultures in the cheese industry.