A bacterium that degrades and assimilates poly(ethylene terephthalate)

We have serious concerns about discrepancy between the description of the paper and the fact withdrawn from data.
Our questions are shown below.
1. No information for the source of the PET film (1.9% crystallinity; lcPET) or the method to make the unusual PET film. It is well known that degradability is highly affected by crystallinity.
2. Fig. 1C: miscalculation
The weight of PET film (20150.2 mm) was described as 60 mg. However, as described in the Supplementary materials, the specific density of PET used was 1.3378 g/cm3 (approx. 1.34), giving a calculated weight of approximately 80.4 mg. Also, in Fig. S1 and Fig. 1H, the size and weight of PET film were described as 20150.2 mm and 60 mg, respectively.
3. Fig. 1C and 1H: measurement of weight loss
In our knowledge, to measure the weight of a film slip, it is necessary to remove the attached microbes on the surface, wash, and dry at least overnight at an appropriate temperature. Even for removing the enzyme from the surface, for example, dilute sodium bicarbonate and non-ionic surfactant are used (Oda et al. 2018). Typically a more powerful treatment is required to remove microbes, especially in the case of Ideonella sakaiensis or the consortium no. 46 that have cell appendages. The process to remove microbes was not described. In addition, was the film returned to the same test tube for further incubation? Based on the miscalculations described in 2, how could you obtain the reasonable values shown in the figures (Figs.1C and 1H)? Even if 60 mg was lost from the film (20150.2 mm=60 mm3; approx. 80.4 mg), approx. 20 mg must remain.
4. Fig.2D: Degradation rate of PET by PETase
Degradation ability of PETase for lcPET and high crystallinity PET (not specified) were 0.23% and 0.009%, respectively (See Table S2 of Kawai et al. 2019). These degradation rates correspond to the surface hydrophilization level (PET surface-modifying enzyme), but not the inner block degradation level (PET hydrolase) (See Kawai et al. 2019). As hydrophilization of PET fibers and films by various hydrolases had previously been reported, the findings in this paper were not new. Degradation of amorphous PET film (Goodfellows Cambridge Ltd.; 6-7% crystallinity) has been reported by several cutinases to be more than 10 % up to approx. 100 % at around 60–70 C (Wei and Zimmermann 2017).
5. Fig. 3 and Fig. S13: PETase homologues
The paper stated that no microbe equipped with all the metabolic systems for PET metabolism (PETase, MHETase, TPA dioxygenase, and PCA dioxygenase) was found in database. All of the 92 microbial species tested possess MHET homologues and 33 of those species possess homologues of TPA and PCA dioxygenases. Fig. S13 shows the presence of a PETase homologue in Amycolatopsis mediterranei, although it is not described at all. We disclosed that many PETase homologues with over 65% identities exist in mesophilic bacteria (Kawai et al. 2019). Poly(tetramethylene succinate) depolymerase from Acidovorax delafieldii strain BS-3 (Uchida et al. 2002) has the highest identity (82%) with PETase. We wonder why the authors in this paper missed these facts at the point of the publication. In general, the homology search is practiced when cloned.

In conclusion, probably Ideonella sakaiensis can grow on a specific PET, which the origin is not identified and nobody else cannot obtain. More importantly, its crystallinity (1.9%) is far low, compared with generally recognized amorphous PET (approximately 6-8%). Nevertheless, the degradation ability of PETase is too low (only 0.23%). Our thermostable PET hydrolase can degrade PET microfiber by more than 20%, although degradation of amorphous PET films is far lower than 1% at 30 C (See Kawai et al. 2019). Thus, the enzymatic PET hydrolysis must be evaluated, based on the physical properties of PET used. Your publication misled the public and media, as if Ideonella sakaiensis and PETase can be the Savior or a trump in the recycling of PET in the future. We expect your responsible answers for our questions.

References
Kawai F, Kawabata T, Oda M (2019) Current knowledge on enzymatic PET degradation and its possible application to waste stream management and other fields, Appl Microbiol Biotechnol, published online on April 8, 2019: DOI: 10.1007/s00253-019-09717-y
Oda M, Yamagami Y, Inaba S, Oida T, Yamamoto M, Kitajima S, Kawai F (2018) Enzymatic hydrolysis of PET: functional roles of three Ca2+ ions bound to a cutinase-like enzyme, Cut190*, and its engineering for improved activity, Appl Microbiol Biotechnol 102: 10067-10077
Uchida H, Shigeno-Akutsu Y, Nomura N, Nakahara T, Nakajima-Kambe T (2002) Cloning and sequence analysis of poly(tetramethylene succinate) depolymerase from Acidovorax delafieldii strain BS-3. J Biosci Bioeng 93: 245-247
Wei R, Zimmermann W (2017) Biocatalysis as a green route for recycling the recalcitrant plastic polyethylene terephthalate, Microb Biotechnol 10: 1302-1307