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Aims: To characterize the bacterial community of taberna, an alcoholic traditional beverage from the Southern part of Mexico produced by the fermentation of the coyol palm sap ( Acrocomia aculeate). Methods and Results: Bacterial 16S rDNA libraries were constructed from metagenomic DNA extracted during the fermentation process at 0, 60 and 108 h. A total of 154 clones were sequenced, and 13, 10 and nine unique sequences were found at each sampling time. At the onset of the fermentation, Zymomonas mobilis, Fructobacillus spp., Pantoea agglomerans and other Gammaproteobacteria were detected. After 60 h, lactic acid bacteria were found and 30% of clones in the library were related to Lactobacillus nagelii, L. sucicola and L. sp. By the end of the experiment, i.e. after 108 h, the bacterial community included Z. mobilis, Lact. nagelii and Acetobacter pasteurianus. Conclusions: Our results suggest that Z. mobilis population represented an important proportion of the bacterial community (60-80%), as well as the lactobacilli during the fermentation process. The bacterial diversity was low and decreased as the fermentation progressed. Significance and Impact of the Study: This culture-independent study suggests that Z. mobilis and lactobacilli play an important role in the alcoholic fermentation of the taberna beverage. [ABSTRACT FROM AUTHOR]

A wide diversity of organisms exists in soil. Well-adapted groups can be found in extreme environments. A great economic and metabolic potential for extremozymes produced by organisms living at extreme environments has been reported. Extreme characteristics such as high salt content and high pH level make the soil of the former Texcoco Lake a unique place which has not been exploited. Therefore, in this study, 66 strains from soil of the former Texcoco Lake were isolated and phylogenetically analyzed using universal oligonucleotide primers. Different genera such as Kocuria, Micrococcus, Nesterenkonia, Halomonas, Salinicoccus, Kurthia, Gracilibacillus, and Bacillus were found. However, only 22 from all isolated strains were identified at specie level.

A novel Gram-positive, rod-shaped, spore-forming bacterium, designated 13CC(T) was isolated from soil of the former lake Texcoco. The strain was aerobic, catalase-positive and oxidase-negative. It grew at salinities of 0-26% (w/v) NaCl with an optimum at 9-16% (w/v) NaCl. The cells contain peptidoglycan type A1γ, A1γ' with glycine instead of l-alanine and three variations of peptidoglycan type A4γ. The only quinone detected was MK-7. The major fatty acid was anteiso-C(15:0). The polar lipids fraction consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and three different phospholipids. The DNA G+C content was 37.5 mol%. Maximum-likelihood phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 13CC(T) was closely related to members of the genus Bacillus and shared 92.35% similarity with Bacillus agaradhaerens, 92.28% with Bacillus neizhouensis and 92.21% with Bacillus locisalis. It is proposed based on the phenotypic, genotypic and phylogenetic analyses that the novel isolate should be classified as a representative of a new genus and novel species, for which the name Texcoconibacillus texcoconensis gen. nov., sp. nov. is proposed. The type strain of Texcoconibacillus texcoconensis is 13CC(T) ( =JCM 17654(T) =DSM 24696(T)).

Assimilatory nitrate reduction (ANR) is a pathway wherein NO(3)(-) is reduced to NH(4)(+), an N species that can be incorporated into the biomass. There is little information about the ANR genes in Archaea and most of the known information has been obtained from cultivable species. In this study, the diversity of the haloarchaeal assimilatory nitrate-reducing community was studied in an extreme saline alkaline soil of the former lake Texcoco (Mexico). Genes coding for the assimilatory nitrate reductase (narB) and the assimilatory nitrite reductase (nirA) were used as functional markers. Primers to amplify and detect partial narB and nirA were designed. The analysis of these amplicons by cloning and sequencing showed that the deduced protein fragments shared >45% identity with other NarB and NirA proteins from Euryarchaeota and <38% identity with other nitrate reductases from Bacteria and Crenarchaeota. Furthermore, these clone sequences were clustered within the class Halobacteria with strong support values in both constructed dendrograms, confirming that desired PCR products were obtained. The metabolic capacity to assimilate nitrate by these haloarchaea seems to be important given that at pH 10 and higher, NH(4)(+) is mostly converted to toxic and volatile NH(3), and NO(3)(-) becomes the preferable N source.

The diversity of the dissimilatory and respiratory nitrate-reducing communities was studied in two soils of the former lake Texcoco (Mexico). Genes encoding the membrane-bound nitrate reductase (narG) and the periplasmic nitrate reductase (napA) were used as functional markers. To investigate bacterial communities containing napA and narG in saline alkaline soils of the former lake Texcoco, libraries of the two sites were constructed (soil T3 with pH 11 and electrolytic conductivity in saturated extract (EC(SE)) 160 dS m(-1) and soil T1 with pH 8.5 and EC(SE) 0.8 dS m(-1)). Phylogenetic analysis of napA sequences separated the clone families into two main groups: dependent or independent of NapB. Most of napA sequences from site T1 were grouped in the NapB-dependent clade, meanwhile most of the napA sequences from the extreme soil T3 were affiliated to the NapB-independent group. For both sites, partial narG sequences were associated with representatives of the Proteobacteria, Firmicutes and Actinobacteria phyla, but the proportions of the clones were different. Our results support the concept of a specific and complex nitrate-reducing community for each soil of the former lake Texcoco.

The soil of the former lake Texcoco is an extreme environment localized in the valley of Mexico City, Mexico. It is highly saline and alkaline, where Na+, Cl(-), HCO3(-) and CO3(2-) are the predominant ions, with a pH ranging from 9.8 to 11.7 and electrolytic conductivities in saturation extracts from 22 to 150 dS m(-1). Metagenomic DNA from the archaeal community was extracted directly from soil and used as template to amplify 16S ribosomal gene by PCR. PCR products were used to construct gene libraries. The ribosomal library showed that the archaeal diversity included Natronococcus sp., Natronolimnobius sp., Natronobacterium sp., Natrinema sp., Natronomonas sp., Halovivax sp., "Halalkalicoccus jeotgali" and novel clades within the family of Halobacteriaceae. Four clones could not be classified. It was found that the archaeal diversity in an alkaline-saline soil of the former lake Texcoco, Mexico, was low, but showed yet uncharacterized and unclassified species.