Insights into catalytic action mechanism of Pseudomonas mendocina 3121-1 lipase

Novel leaderless bacteriocin geobacillin 6 from thermophilic bacterium Parageobacillus thermoglucosidasius

Bacterial resistance to conventional antibiotics has urged us to develop alternative strategies against bacterial pathogens. Moreover, a demand for food products containing no chemical preservatives has led us to search for new alternative technologies for food preservation. Bacteriocins - ribosomally synthesized antimicrobial peptides - have been proposed as a new alternative to conventional antibiotics or chemicals for food preservation. This study describes biosynthesis and characterization of a novel leaderless bacteriocin, geobacillin 6, which was identified in the thermophilic bacterium Parageobacillus thermoglucosidasius. Its amino acid sequence shows low similarity to other bacteriocins and it is the first leaderless-type bacteriocin identified in thermophilic bacteria. Based on structure assessment, the bacteriocin forms a multi-helix bundle. Geobacillin 6 exhibits a relatively narrow antimicrobial spectrum, it is active in the μM range and against Gram-positive bacteria, mostly thermophilic species closely related to the producer strain. Bacteriocin demonstrates stability over pH 3-11 and is highly thermostable, retaining 100% of its activity after incubation at 95°C for 6 h. Geobacillin 6 has potential in the food industry and biotechnological processes where contamination with thermophilic bacteria is undesirable.

Investigation of amino acids related to Staphylococcus saprophyticus AG1 EstAG1 carboxylesterase catalytic function revealed a new family of bacterial lipolytic enzymes

Most of the lipolytic enzymes (carboxylesterases, EC 3.1.1.1 and triacylglycerol acylhydrolases, EC 3.1.1.3) originate from bacteria and form a large group of functionally important enzymes that are also well known for their use in multiple biotechnology sectors. Rapid and increasing amount of bacterial lipolytic enzymes being discovered and characterized led to a necessity to classify them. More than twenty years ago bacterial lipolytic enzymes were originally classified into eight families and six true lipase sub-families based on the differences in their amino acid sequences and biochemical properties. Later, this classification was comprehensively updated to 19 families with eight subfamilies, and more recently, employing deeper comparative analysis methods, classification expanded to 35 families and 11 subfamilies. Bacterial lipolytic enzymes that cannot be classified into currently existing families are still being discovered. This work provides site-directed mutagenesis and differential scanning fluorimetry based investigation of catalytic function-related amino acids of previously discovered and characterized EstAG1 carboxylesterase from Staphylococcus saprophyticus AG1. Experimental results obtained in this work revealed that EstAG1 carboxylesterase can be placed into a new family of bacterial lipolytic enzymes.

A cleaner process of deinking waste paper pulp using Pseudomonas mendocina ED9 lipase supplemented enzyme cocktail

Lipase enzyme has a critical role in deinking process along with other lignocellulosic enzymes. In this paper, we try to demonstrate the role of lipase in the enzyme cocktail used for enzymatic deinking. For this, we identified a potential lipolytic bacterium, Pseudomonas mendocina ED9 isolated from elephant dung with a molecular weight of 35 kDa. During the Box-Benhken model optimization, a maximum lipase activity of 105.12 U/g, which was 12.36-fold higher than the initial enzyme activity and 1.3-fold higher than the activity obtained during the Plackett Burman design, was achieved. A maximum lipase activity of 105.12 U/g was obtained after optimization. Ammonium sulphate (60%) precipitation resulted in a specific activity of 68.19 U/mg with a 1.4-fold purification and yield of 64%. Lipase from P. mendocina ED9 exhibited a Km of 0.5306 mM and Vmax of 25.0237 μmol/min/mg. A Δ brightness of approximately 14.5% were achieved during the enzymatic deinking using cocktail comprised of cellulase, xylanase and lipase. This reports the significant role and efficacy of lipase in enzyme cocktails for deinking applications. This formulation will reduce the pollution and environmental toxicity of conventional chemical deinking.

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.

Synthesis of trimethylolpropane esters of oleic acid by Lipoprime 50T

The ability of the commercial lipolytic enzyme Lipoprime 50T to catalyze the biotechnologically important synthesis of the biodegradable and environmentally acceptable trimethylolpropane (2-ethyl-2-(hydroxymethyl)-1,3-propanediol) ester of oleic acid was investigated. Simple and accurate thin-layer chromatography and computer analysis methods were used that enable one to follow changes of all reaction mixture components simultaneously. The processes of transesterification and esterification were compared. The effects of the molar ratio of the substrates, reaction temperature, time, and medium on the composition of the reaction mixture were analyzed. Esterification was determined to be more preferable than transesterification in both studied solvents. Under the optimal conditions identified (15% w/w water, temperature 60°C, trimethylolpropane to oleic acid molar ratio 1:3.5, and reaction time 72 h), the highest trimethylolpropane trioleate yield of around 62% and trimethylolpropane mono-, di-, and trioleate overall yield of about 83% were obtained. Although the yields are not high enough for industrial application, the process shows the potential to be optimized for higher yields in the near future as the conversions were obtained at ambient pressure, whereas many other processes described in the literature are conducted under vacuum at a specific pressure.