An esterase carrying both a secretion signal and a membrane-bound lipid anchor is a statement about geography [12]. The protein is sent out of the cell and then stays fixed to its outside, which is the arrangement you would need to explain the holes the Konstanz group found in film recovered from the humus, each one the size and shape of a single bacterium [9]. Lerner's reading is that the cells wear their depolymerases and eat their way in until they sit embedded in the material [10].
The antibiotic half of the finding rests on two things. The structure resembles beta-lactamases as well as esterases, and beta-lactamases are what make bacteria resistant to penicillin, by cleaving the antibiotic's beta-lactam ring [13]. And the enzyme, in the team's laboratory tests, does both jobs [14]. The nickname comes from a wide-open active site [2], which is the sort of feature that tends to tolerate substrates it was not built for. What this does not tell you is whether a bacterium carrying the gene survives a clinically relevant dose of penicillin, whether the two reactions run through the same catalytic residues, or whether the gene sits on anything that moves between species.
It is worth being precise about how the gene surfaced. It was enriched only in the soil that had LCAP buried in it [12], which is an association between substrate and gene abundance in samples where the plastic was disappearing. The biochemistry, run on the protein rather than in the soil, is what converts that association into a claim about function [14].
The degradation numbers are cleaner than most biodegradability claims, largely because of the controls: cellulose, PHBV, PCL, HDPE and untreated soil [7]. Every bioplastic went to completion in roughly 250 to 330 days, cellulose in about 80, and HDPE showed virtually none over the year of monitored CO2 [8][6]. So the bioplastics took about three to four times the cellulose timeline (250/80 = 3.1, 330/80 = 4.1) [19]. The flat HDPE line is what makes the rest worth reading; an assay that degrades whatever you put in it has measured nothing.
The films came from Stefan Mecking's group, and the field arm sat in the humus layer where plant polyesters such as cutin are already turned over [4][5]. That is close to the friendly case for an enzyme like this. The problem the paper opens with is marine, where the synthetic polymers in use today break down biologically only very slowly and fragment into micro- and nanoplastics instead [15], and a year in forest soil sets no clock for that. Colonised plastic is already a habitat with its own biofilms [16], which is where selection of the kind implied here would actually happen. Konstanz reads the discovery as evidence that microbes may adapt to plastic faster than expected [17]; the same gene is the reason to ask what else that adaptation brings with it.
