Mining lipolytic enzymes in community DNA from high Andean soils using a targeted approach

The microbiome of the ice-capped Cayambe Volcanic Complex in Ecuador

A major challenge in microbial ecology is to understand the principles and processes by which microbes associate and interact in community assemblages. Microbial communities in mountain glaciers are unique as first colonizers and nutrient enrichment drivers for downstream ecosystems. However, mountain glaciers have been distinctively sensitive to climate perturbations and have suffered a severe retreat over the past 40  years, compelling us to understand glacier ecosystems before their disappearance. This is the first study in an Andean glacier in Ecuador offering insights into the relationship of physicochemical variables and altitude on the diversity and structure of bacterial communities. Our study covered extreme Andean altitudes at the Cayambe Volcanic Complex, from 4,783 to 5,583 masl. Glacier soil and ice samples were used as the source for 16S rRNA gene amplicon libraries. We found (1) effects of altitude on diversity and community structure, (2) the presence of few significantly correlated nutrients to community structure, (3) sharp differences between glacier soil and glacier ice in diversity and community structure, where, as quantified by the Shannon γ-diversity distribution, the meta-community in glacier soil showed more diversity than in glacier ice; this pattern was related to the higher variability of the physicochemical distribution of variables in the former substrate, and (4) significantly abundant genera associated with either high or low altitudes that could serve as biomarkers for studies on climate change. Our results provide the first assessment of these unexplored communities, before their potential disappearance due to glacier retreat and climate change.

Atypical organic-solvent tolerant bacterial hormone sensitive lipase-like homologue EstAG1 from Staphylococcus saprophyticus AG1: Synthesis and characterization

Biocatalysts exerting activity against ester bonds have a broad range of applications in modern biotechnology. Some of the most industrially relevant enzymes of this type are lipolytic and their market is predicted to uphold leadership up till 2024. In this study, a novel bacterial hormone-sensitive lipase-like (bHSL) family homologue, designated EstAG1, was discovered by mining gDNA of bacteria isolated from fat contaminated soil in Lithuania. Putative lipolytic enzyme was cloned, overexpressed in E. coli, purified and characterized determining its biochemical properties. While the true physiological role of the discovered leaderless, ~36 kDa enzyme is unknown, metal-activated EstAG1 possessed optima at 45-47.5 °C, pH 7.5-8, with a generally intermediate activity profile between esterases and lipases. Furthermore, EstAG1 was hyperactivated by ethanol, dioxane and DMSO, implicating that it could be industrially applicable enzyme for the synthesis of valuable products such as biodiesel, flavor esters, etc. Sequence analysis and structure modeling revealed that the highest sequence homology of EstAG1 with the closest structurally and functionally described protein makes up only 26%. It was also revealed that EstAG1 has some differences in the bHSL family-characteristic conserved sequence motives. Therefore, EstAG1 presents interest both in terms of biotechnological applications and basic research.

Enhanced halophilic lipase secretion by Marinobacter litoralis SW-45 and its potential fatty acid esters release

An approach was made to enhance the halophilic lipase secretion by a newly isolated moderate halophilic Marinobacter litoralis SW-45, through the statistical optimization of Plackett-Burman (PB) experimental design and the Face Centered Central Composite Design (FCCCD). Initially, PB statistical design was used to screen the medium components and process parameters, while the One-factor-at-a-time technique was availed to find the optimum level of significant parameters. It was found that MgSO₄  · 7H₂ O, NaCl, agitation speed, FeSO₄  · 7H₂ O, yeast extract and KCl positively influence the halophilic lipase production, whereas temperature, carbon source (maltose), inducer (olive oil), inoculum size, and casein-peptone had a negative effect on enzyme production. The optimum level of halophilic lipase production was obtained at 3.0 g L^-1 maltose, 1% (v/v) olive oil, 30 °C growth temperature and 4% inoculum volume (v/v). Further optimization by FCCCD was revealed 1.7 folds improvement in the halophilic lipase production from 0.603 U ml^-1 to 1.0307 U ml^-1 . Functional and biochemical characterizations displayed that the lipase was significantly active and stable in the pH ranges of 7.0-9.5, temperature (30-50 °C), and NaCl concentration (0-21%). The lipase was maximally active at pH 8.0, 12% (w/v) NaCl, and 50 °C temperature. Besides, M. litoralis SW-45 lipase was found to possess the promising industrial potential to be utilized as a biocatalyst for the esterification.