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Total length ([L.sub.T]) and standard length ([L.sub.s])(mm) were compared to weight [M.sub.B](g) in the Spottail Shiner, Notropis hudsonius (Clinton 1824), in the Western Basin of Lake Erie. Length and weight relationship (n = 529), length-frequency distribution, and sex ratio were evaluated for tributary habitats and compared to coastal habitats. The total population had a positive correlation between log normalized [L.sub.T] and [M.sub.B] (y = 3.0902x-5.2289, [R.sup.2]= 0.995) and a positive correlation between [L.sub.s] and [M.sub.B] (y = 3.1397x-5.0501, [R.sup.2]= 0.996). Male Spottail Shiner had a positive correlation between log normalized [L.sub.T] and [M.sub.B] (y = 3.0984x-5.2465, [R.sup.2]= 0.995,) and a significant positive correlation between log normalized standard length and body weight (y = 3.1551x-5.0775, [R.sup.2]= 0.996). Female Spottail Shiner had a positive correlation between log normalized [L.sub.T]. and [M.sub.B] (y = 3.078x-5.2034, [R.sup.2]= 0.993) and a positive correlation between log normalized [L.sub.s] and [M.sub.B] (y = 3.1338x-5.0393, [R.sup.2]= 0.996). Males and females were not significantly different in [L.sub.T] or [L.sub.s] (F-test = 1.020, df = 260, 267, p = 0.437). Sex ratio was 1:1. Spottail Shiner exhibit indeterminate growth and did not exhibit gender influenced growth patterns. Tributary individuals were significantly smaller than coastal individuals (F-test = 0.346, df = 65, 202, p = < 0.001). Male age I individuals ranged from 12-54 mm, age II individuals ranged from 57-99 mm, and age III individuals ranged from 99-132 mm. Female Age I individuals ranged from 12-48 mm, age II individuals ranged from 53-102 mm, and age III individuals ranged from 102-129 mm., INTRODUCTION The family Cyprinidae consists of minnows and carp and is the largest family of freshwater fishes in the world (Nelson 2006). Minnows are essential to energy transfer from lower [...]

There is keen interest to develop new technologies to recycle the plastic poly(ethylene terephthalate) (PET). To this end, the use of PET‐hydrolyzing enzymes has shown promise for PET deconstruction to its monomers, terephthalate (TPA) and ethylene glycol (EG). Here, the Ideonella sakaiensis PETase wild‐type enzyme was compared to a previously reported improved variant (W159H/S238F). The thermostability of each enzyme was compared and a 1.45 Å resolution structure of the mutant was described, highlighting changes in the substrate binding cleft compared to the wild‐type enzyme. Subsequently, the performance of the wild‐type and variant enzyme was compared as a function of temperature, substrate morphology, and reaction mixture composition. These studies showed that reaction temperature had the strongest influence on performance between the two enzymes. It was also shown that both enzymes achieved higher levels of PET conversion for substrates with moderate crystallinity relative to amorphous substrates. Finally, the impact of product accumulation on reaction progress was assessed for the hydrolysis of both PET and bis(2‐hydroxyethyl) terephthalate (BHET). Each enzyme displayed different inhibition profiles to mono(2‐hydroxyethyl) terephthalate (MHET) and TPA, while both were sensitive to inhibition by EG. Overall, this study highlights the importance of reaction conditions, substrate selection, and product accumulation for catalytic performance of PET‐hydrolyzing enzymes, which have implications for enzyme screening in the development of enzyme‐based polyester recycling. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET) is one of the most ubiquitous plastics and can be depolymerized through biological and chemo-catalytic routes to its constituent monomers, terephthalic acid (TPA) and ethylene glycol (EG). TPA and EG can be re-synthesized into PET for closed-loop recycling or microbially converted into higher-value products for open-loop recycling. Here, we expand on our previous efforts engineering and applying Pseudomonas putida KT2440 for PET conversion by employing adaptive laboratory evolution (ALE) to improve TPA catabolism. Three P. putida strains with varying degrees of metabolic engineering for EG catabolism underwent an automation-enabled ALE campaign on TPA, a TPA and EG mixture, and glucose as a control. ALE increased the growth rate on TPA and TPA-EG mixtures by 4.1- and 3.5-fold, respectively, in approximately 350 generations. Evolved isolates were collected at the midpoints and endpoints of 39 independent ALE experiments, and growth rates were increased by 0.15 and 0.20 h -1 on TPA and a TPA-EG, respectively, in the best performing isolates. Whole-genome re-sequencing identified multiple converged mutations, including loss-of-function mutations to global regulators gacS, gacA, and turA along with large duplication and intergenic deletion events that impacted the heterologously-expressed tphAB II catabolic genes. Reverse engineering of these targets confirmed causality, and a strain with all three regulators deleted and second copies of tphAB II and tpaK displayed improved TPA utilization compared to the base strain. Taken together, an iterative strain engineering process involving heterologous pathway engineering, ALE, whole genome sequencing, and genome editing identified five genetic interventions that improve P. putida growth on TPA, aimed at developing enhanced whole-cell biocatalysts for PET upcycling., Competing Interests: Declaration of Competing Interest No competing interests., (Copyright © 2024. Published by Elsevier Inc.)