Pennacchio A

References (2)

Title : Microorganisms that produce enzymes active on biodegradable polyesters are ubiquitous - Degli-Innocenti_2023_Biodegradation__
Author(s) : Degli-Innocenti F , Breton T , Chinaglia S , Esposito E , Pecchiari M , Pennacchio A , Pischedda A , Tosin M
Ref : Biodegradation , : , 2023
Abstract : Biodegradability standards measure ultimate biodegradation of polymers by exposing the material under test to a natural microbial inoculum. Available tests developed by the International Organization for Standardization (ISO) use inoculums sampled from different environments e.g. soil, marine sediments, seawater. Understanding whether each inoculum is to be considered as microbially unique or not can be relevant for the interpretation of tests results. In this review, we address this question by consideration of the following: (i) the chemical nature of biodegradable plastics (virtually all biodegradable plastics are polyesters) (ii) the diffusion of ester bonds in nature both in simple molecules and in polymers (ubiquitous); (iii) the diffusion of decomposers capable of producing enzymes, called esterases, which accelerate the hydrolysis of esters, including polyesters (ubiquitous); (iv) the evidence showing that synthetic polyesters can be depolymerized by esterases (large and growing); (v) the evidence showing that these esterases are ubiquitous (growing and confirmed by bioinformatics studies). By combining the relevant available facts it can be concluded that if a certain polyester shows ultimate biodegradation when exposed to a natural inoculum, it can be considered biodegradable and need not be retested using other inoculums. Obviously, if the polymer does not show ultimate biodegradation it must be considered recalcitrant, until proven otherwise.
ESTHER : Degli-Innocenti_2023_Biodegradation__
PubMedSearch : Degli-Innocenti_2023_Biodegradation__
PubMedID: 37354274

Title : Enlarging the substrate portfolio of the thermophilic esterase EST2 from Alicyclobacillus acidocaldarius - Pennacchio_2015_Extremophiles_19_1001
Author(s) : Pennacchio A , Mandrich L , Manco G , Trincone A
Ref : Extremophiles , 19 :1001 , 2015
Abstract : The enzymatic regioselective hydrolysis of (a) acetylated mono- to tetrasaccharides of different nature, (b) of acetylated aryl glycosides and (c) of different acetylated nucleosides was studied enlarging the portfolio of substrates that can be employed by the thermophilic esterase EST2 from Alicyclobacillus acidocaldarius. The reactions were optimised to the extent that the amount of enzyme needed was lowered of two orders of magnitude with respect to the previously reported reactions, namely from 4000 to 40 U of enzyme per reaction. New additional solvents were screened and dramatic changes in regioselectivity were observed depending on the amount and type of solvent used. For example, in the presence of 10 % DMF, only two alpha-D-glucose products 6-OH and 4,6-OH (in a 76:24 ratio) were detected, whereas with 25 % DMF, at least four products of similar amount were observed. This versatility adds specific value to the biocatalyst making possible the design of biocatalytic reactions with different hydrophobic ester substrates. As an additional remarkable example, EST2 catalysed with a good yield and high regioselectivity the hydrolysis of p-nitrophenyl beta-D-xylopyranoside triacetate producing only the monoacetylated derivative with acetyl group in 3-O-position, in 2 min. The results with nucleosides as substrates are particularly interesting. The peracetates of 3',5'-di-O-acetylthymidine are converted almost quantitatively (95 %) to the monoacetylated derivative possessing free secondary OH; this regioselectivity is complementary to hydrolysis/alcoholysis reactions catalysed by CAL-B lipase or to other microbial hydrolytic biocatalysts, generally giving products with free primary OH groups. A docking analysis was undertaken with all analysed substrates suggesting a structural interpretation of the results. In most of cases, the best pose of the selected substrate was in line with the observed regioselectivity.
ESTHER : Pennacchio_2015_Extremophiles_19_1001
PubMedSearch : Pennacchio_2015_Extremophiles_19_1001
PubMedID: 26216109
Gene_locus related to this paper: aliac-est2