Conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) have gained significant attention due to their anticarcinogenic and lipid/energy metabolism-modulatory effects. However, their concentration in foodstuffs is insufficient for any therapeutic application to be implemented. From a biotechnological standpoint, microbial production of these conjugated fatty acids (CFAs) has been explored as an alternative, and strains of the genera ,, and have shown promising producing capacities. Current screening research works are generally based on direct analytical determination of production capacity (e.g., trial and error), representing an important bottleneck in these studies. This review aims to summarize the available information regarding identified genes and proteins involved in CLA/CLNA production by these groups of bacteria and, consequently, the possible enzymatic reactions behind such metabolic processes. Linoleate isomerase (LAI) was the first enzyme to be described to be involved in the microbiological transformation of linoleic acids (LAs) and linolenic acids (LNAs) into CFA isomers. Thus, the availability of gene sequences has allowed the development of genetic screening tools. Nevertheless, several studies have reported that LAIs have significant homology with myosin-cross-reactive antigen (MCRA) proteins, which are involved in the synthesis of hydroxy fatty acids, as shown by hydratase activity. Furthermore, it has been suggested that CLA and/or CLNA production results from a stress response performed by the activation of more than one gene in a multiple-step reaction. Studies on CFA biochemical pathways are essential to understand and characterize the metabolic mechanism behind this process, unraveling all the gene products that may be involved. As some of these bacteria have shown modulation of lipid metabolism , further research to be focused on this topic may help us to understand the role of the gut microbiota in human health.

One Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, and coccobacilli-shaped strain, designated c10Ua161MT, was isolated from a urine sample from a reproductive-age healthy woman. Comparative 16S rRNA gene sequence analysis indicated that strain c10Ua161MT belonged to the genus Lactobacillus . Phylogenetic analysis based on pheS and rpoA gene sequences strongly supported a clade encompassing strains c10Ua161MT and eight other strains from public databases, distinct from currently recognized species of the genus Lactobacillus. In silico Average Nucleotide Identity (ANI) and Genome-to-Genome Distance Calculator (GGDC), showed 87.9 and 34.3 % identity to the closest relative Lactobacillus jensenii , respectively. The major fatty acids of strain c10Ua161MT were C18 : 1ω9c (65.0%), C16 : 0 (17.8%), and summed feature 8 (10.2 %; comprising C18 : 1ω7c, and/or C18 : 1ω6c). The DNA G+C content of the strains is 34.2 mol%. On the basis of data presented here, strain c10Ua161MT represents a novel species of the genus Lactobacillus , for which the name Lactobacillus mulieris sp. nov. is proposed. The type strain is c10Ua161MT (=CECT 9755T=DSM 108704T).

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Lipids are gaining relevance over the last 20 years, as our knowledge about their role has changed from merely energy/structural molecules to compounds also involved in several biological processes. This led to the creation in 2003 of a new emerging research field: lipidomics. In particular the phospholipids have pharmacological/food applications, participate in cell signalling/homeostatic pathways while their analysis faces some challenges. Their fractionation/purification is, in fact, especially difficult, as they are amphiphilic compounds. Moreover, it usually involves SPE or TLC procedures requiring specific materials hampering their suitableness for routine analysis. Finally, they can interfere with the ionization of other molecules during mass spectrometry analysis. Thus, simple high-throughput reliable methods to selectively isolate these compounds based on the difference between chemical characteristics of lipids would represent valuable tools for their study besides that of other compounds. The current review work aims to describe the state-of-the-art related to the extraction of phospholipids using liquid-liquid methods for their targeted isolation. The technological and biological importance of these compounds and ion suppression phenomena are also reviewed. Methods by precipitation with acetone or isolation using methanol seem to be suitable for selective isolation of phospholipids in both biological and food samples.