Parental Strain Research Articles

Virtual Behavioral Skills Training for Parents: Generalization of Parent Behavior and Child Learning

Virtual Behavioral Skills Training for Parents: Generalization of Parent Behavior and Child Learning

Comparison of the Effectiveness of Online and Face-to-Face Parent Training for Parents of Children With Developmental Disabilities

Comparison of the Effectiveness of Online and Face-to-Face Parent Training for Parents of Children With Developmental Disabilities

Diversity of Neurotransmitter-Producing Human Skin Commensals

Recent findings indicate that human microbiota can excrete trace amines, dopamine, and serotonin. These neurotransmitters (NTs) can either affect classical neurotransmitter signaling or directly trigger trace amine-associated receptors (TAARs), with still unclear consequences for host physiology. Compared to gut microbiota, less information is available on the role of skin microbiota in NT production. To explore this, 1909 skin isolates, mainly from the genera Staphylococcus, Bacillus, and Corynebacterium, were tested for NT production. Only 6.7% of the isolates were capable of producing NTs, all of which belonged to the Staphylococcus genus. Based on substrate specificity, we identified two distinct profiles among the NT producers. One group primarily produced tryptamine (TRY) and phenylethylamine (PEA), while the other mainly produced tyramine (TYM) and dopamine (Dopa). These differing production profiles could be attributed to the activity of two distinct aromatic amino acid decarboxylase enzymes, SadA and TDC, responsible for generating the TRY/PEA and TYM/Dopa product spectra, respectively. SadA and TDC orthologues differ in structure and size; SadA has approximately 475 amino acids, whereas the TDC type consists of about 620 amino acids. The genomic localization of the respective genes also varies: tdc genes are typically found in small, conserved gene clusters, while sadA genes are not. The heterologous expression of sadA and tdc in Escherichia coli yielded the same product spectrum as the parent strains. The possible effects of skin microbiota-derived NTs on neuroreceptor signaling in the human host remain to be investigated.

Cry1 resistance in a CRISPR/Cas9-mediated HaCad1 gene knockout strain of the Australian cotton bollworm Helicoverpa armigera conferta (Lepidoptera: Noctuidae).

Helicoverpa armigera is a highly polyphagous species that causes huge losses to agricultural and horticultural crops worldwide. In the cotton industry, H. armigera, including the Australian subspecies Helicoverpa armigera conferta, is largely managed using genetically modified crops that express insecticidal toxins, such as Cry1Ac. Resistance to Cry1 proteins occurs and, in some cases, is mediated by changes to HaCad1, a gene that encodes the midgut protein cadherin. Around the world, numerous resistance-associated polymorphisms have been identified in the HaCad1 gene of H. armigera, but Cry1Ac resistance is rare in the Australian subspecies. We used CRISPR/Cas9 to disrupt the cadherin gene in H. armigera conferta and characterised the resulting phenotype with bioassays and transcriptomics. Compared to the parental strain, the newly generated HaCad1 knockout strain is 44-fold and 16-fold more resistant to Cry1Ac and Cry1A.105, respectively, while wild-type and knockout insects were equally insensitive to Cry1F. The disruption of the HaCad1 gene causes Cry1Ac resistance in Australian H. armigera conferta. However, Cry1Ac resistance remains rare in Australian field populations suggesting that Australia's approach to pest management in cotton has prevented widespread Cry1Ac resistance. © 2024 CSIRO. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Menaquinone production in genetically engineered E. coli.

Menaquinone (MK) is an important electron transporter in Escherichia coli. This isoprenoid quinone can transfer electrons to many terminal acceptors, such as fumarate and nitrate, which helps this organism survive under diverse and challenging conditions. As the isoprenoid quinones with various length of isoprenyl tail are widely distributed in nature, the heterologous expression of polyprenyl diphosphate synthases (PDSs) has been investigated using its counterpart, ubiquinone (UQ). In this study, we investigated the MK production by the expression of various heterologous PDS genes from prokaryotic and eukaryotic species, including Saccharomyces cerevisiae COQ1 (hexa-PDS), Haemophilus influenzae hi0881 (hepta-PDS), Synechocystis sp. strain PCC6803 slr0611 (nona-PDS) and Glunocobacter suboxydans ddsA (deca-PDS) in E. coli. We detected specific isoforms of MK, including MK7, MK9, and MK10, via the expression of HI0881, Slr0611 and DdsA respectively, but rarely detect MK6 via the expression of Coq1. As UQ6 was detected in E. coli harboring COQ1, the acceptance of the side chain lengths by MenA (prenyl transferase for MK) was narrower than UbiA (prenyl transferase for UQ). We also identified a mutation in menA in the E. coli AN386 strain and a transposon insertion of IS186 in menC in E. coli KO229 (∆ispB) and its parental strain FS1576. Taken together, these results elucidate the different nature of MenA from UbiA.

Gene expression screening and cell factory engineering for enhancing echinocandin B production in Aspergillus nidulans NRRL8112.

Echinocandin B (ECB) is a key precursor of the antifungal drug anidulafungin and its biosynthesis occurs via ani gene cluster in Aspergillus nidulans NRRL8112. Strain improvement for industrial ECB production has mainly relied on mutation breeding due to the lack of genetic tools. Here, a CRISPR-base-editing tool was developed in A. nidulans NRRL8112 for simultaneous inactivation of the nkuA gene and two marker genes, pryoA and riboB, which enabled efficient genetic manipulation. Then, in-vivo plasmid assembly was harnessed for ani gene expression screening, identifying the rate-limiting enzyme AniA and a pathway-specific transcription factor AniJ. Stepwise titer enhancement was achieved by overexpressing aniA and/or aniJ, and ECB production reached 1.5g/L during 5-L fed-batch fermentation, an increase of ~ 30-fold compared with the parent strain. This study, for the first time, revealed the regulatory mechanism of ECB biosynthesis and harnessed genetic engineering for the development of an efficient ECB-producing strain.

Capacity Planning in Paediatric Palliative and Hospice Care: An Italian Case

Although the growing demand for healthcare services has enhanced the occurrence of inefficiencies in care provision, healthcare systems should ensure safe, timely and equitable access to care. In particular, the long waiting lists, the lack of beds, and the shortage of healthcare workforce have highlighted the necessity to effectively manage and strategically plan the available resources. Capacity Planning (CP) contributes to determine what, when, where and how much product or service to deliver, with the goal of analysing and optimizing the use and allocation of human and material resources (e.g., physical spaces, equipment, beds, workforce) based on the demand. CP demonstrates to be extremely relevant for hospital units to schedule appointments, diagnostics, surgeries and admissions. Complex contexts and broader healthcare networks could benefit even more from this approach, helping to coordinate multiple care providers and aligning the available resources with the demand pace. The current research presents the implementation of CP in the context of Paediatric Palliative and Hospice Care (PPHC), delivered in an Italian facility. PPHC provides long-term, interdisciplinary and coordinated care between territorial, ambulatory and hospice services. It encompasses follow-up activities, parental training, end-of-life and respite care. In the Italian case analysed, the shortage of beds affects the quality of care delivered to these patients, in terms of accessibility to the service, effectiveness and timeliness of care. Hence, a CP analysis has been performed to pursue a twofold objective: a) to understand if the current capacity of the facility meets the demand for care; b) to improve productivity through an optimized allocation of resources, particularly the available beds and the healthcare workforce. The expected results involve a more effective use of resources, an increased bed occupancy rate and a reduction in rescheduled admissions due to inadequate planning. Optimizing capacity in this specific setting can serve as a pilot project for other similar contexts, aiming to improve patients’ access to healthcare services, their quality of life and supporting the workforce involved in PPHC. This research offers new insights from both the academic and managerial point of view, providing evidence about the implementation of CP in complex healthcare settings.

Effects of hap2 deletion on mnp/vp transcription in Pleurotus ostreatus grown on lignocellulosic substrates.

The regulatory mechanisms governing expression of genes encoding lignin-modifying enzymes (LME) in white-rot fungi remain largely unexplored. Although molecular cloning has identified CCAAT-boxes frequently located 5'-upstream of these genes, their role in transcriptional regulation is not well understood. This study examines the function of hap2, a gene encoding a hypothetical protein homologous to a component of the CCAAT-binding Hap complex, in the white-rot fungus Pleurotus ostreatus. Deletion of hap2 resulted in significantly reduced Mn2+-dependent peroxidase activity and lignin-degrading capacity compared to the parental strain 20b grown on beech wood sawdust (BWS) medium. Real-time PCR revealed that vp2 transcript levels were significantly lower in hap2 deletants than in 20b grown when cultured on the three solid media consisting of BWS, holocellulose, or Avicel, but not on yeast-malt-glucose (YMG) agar plates. Additionally, glutathione S-transferase (GST) pulldown and electrophoretic mobility shift assays demonstrated that recombinant P. ostreatus Hap2, Hap3, and Hap5 expressed in Escherichia coli form a complex capable of binding to the CCAAT sequence 5'-upstream of vp2 in vitro. These results suggest that Hap2, as part of the CCAAT-binding complex, is essential for transcriptional upregulation of vp2 in P. ostreatus growing on lignocellulosic substrates. KEY POINTS: • P. ostreatus hap2 deletants were generated. • Lignin-degrading capacity was significantly reduced in the hap2 deletants. • vp2 was significantly downregulated upon hap2 deletion.

Mycoplasma bovis 5'-nucleotidase is a virulence factor conferring mammary fitness in bovine mastitis.

Nucleases and 5' nucleotidase (5'-NT) play essential roles in cell biology and are often associated with bacterial virulence. In Mycoplasma spp., which have limited metabolic capacities and rely on nutrient availability, these enzymes are of significant importance for nucleotide salvage. This study explores the potential role of 2 membrane-associated lipoproteins, the major nuclease MnuA and 5'-NT, in Mycoplasma bovis mastitis. Mutants deficient in MnuA (mnuA::Tn) and in 5'-NT (0690::Tn) were identified through genome-wide transposon mutagenesis of M. bovis PG45 type strain and their fitness and virulence were assessed both in vitro, in axenic medium, and in vivo, using murine and cow mastitis models. The mnuA::Tn mutant demonstrated reduced nuclease activity, while 0690::Tn exhibited slow log-phase growth and impaired hydrolase activity towards nucleotides as well as deoxynucleotides (dAMP and dGMP). In comparison to the parent strain, the 0690::Tn mutant displayed markedly reduced fitness, as evidenced by a significant decrease or even absence in post-challenge mycoplasma counts in murine and cow mammary tissues, respectively. Moreover, the 0690::Tn mutant failed to induce mastitis in both experimental models. Conversely, the mnuA::Tn mutant induced inflammation in murine mammary glands, characterized by neutrophil infiltration and increased expression of major inflammatory genes. In cows, the mnuA::Tn was able to cause an increase in somatic cell counts in a manner comparable to the wild type, recruit neutrophils, and induce mastitis. Collectively, these findings provide complementary insights, revealing that disruption of 5'-NT significantly attenuated M. bovis pathogenicity, whereas a MnuA-deficient mutant retained the ability to cause mastitis.

Interventions for Managing Picky Eating in Preschool Children: Literature Review

Introduction: Picky eating in children is a widespread issue that can affect growth and development. Factors contributing to picky eating include parental influence, early feeding practices, and environmental conditions. Addressing picky eating behavior is crucial to prevent long-term negative effects on children's nutrition and health. Objective: This study aimed to evaluate the effectiveness of various interventions, such as sensory education, parent training, oral interventions, massage, and diet adjustments, in improving picky eating behavior in children. Method: A review of 15 studies published between 2013 and 2023 was conducted, focusing on intervention programs for children aged 1-6 years. The studies were selected from databases like PubMed, Science Direct, and Google Scholar. Result: Sensory education helped reduce food rejection by familiarizing children with new foods. Parent training, including cooking classes and the Baby Led Weaning (BLW) method, effectively reduced picky eating. Oral interventions, such as herbal remedies and appetite-enhancing supplements, showed positive outcomes. Massage techniques like Tui Na and tailored dietary plans also contributed to better eating habits in both underweight and overweight children. Conclusion: Interventions including sensory education, parental training, oral treatments, massage, and diet modifications can significantly improve eating behaviors in picky eater children, promoting healthier nutrition and growth.

Physiological Effects of TolC-Dependent Multidrug Efflux Pumps in Escherichia coli: Impact on Motility and Growth Under Stress Conditions.

Enterobacteriaceae possess eight TolC-dependent multidrug efflux pumps: AcrAB-TolC, AcrAD-TolC, AcrEF-TolC, MdtEF-TolC, MdtABC-TolC, EmrAB-TolC, EmrYK-TolC, and MacAB-TolC, which efflux bile salts, antibiotics, metabolites, or other compounds. However, our understanding of their physiological roles remains limited, especially for less-studied pumps like EmrYK-TolC. In this study, we tested the effects on swimming motility and growth under stress conditions of Escherichia coli mutants individually deleted for each inner-membrane transporter component of all eight TolC-dependent pumps, a mutant deleted for the AcrB-accessory protein AcrZ, and a mutant simultaneously deleted for all eight pumps (ΔtolC). We found that all mutants tested, except the ΔemrY and ΔacrZ mutants, displayed increased swimming motility. Additionally, the loss of each individual TolC-dependent pump or AcrZ did not reduce growth and sometimes even enhanced it compared to the parental strain under various growth conditions: temperature (LB at 25, 30, 37, and 42°C), pH (LB at pH 6.0, 7.4, and 9.0; and LB buffered to pH 6.0, 7.4, and 8.25), LB with limited air exchange, and nutritional stress (M9-glucose or M9-glycerol). In contrast, the ΔtolC mutant grew significantly slower than the parental strain under all conditions tested except in LB-TRIS pH 7.4 and LB with limited air exchange. Overall, these findings indicate that while individual TolC-dependent pumps are generally dispensable for growth under many stress conditions in the absence of antimicrobials, possibly due to their partially overlapping substrate profiles, TolC-dependent efflux is required for maximal growth under most conditions.

Modification of Glucose Metabolic Pathway to Enhance Polyhydroxyalkanoate Synthesis in Pseudomonas putida

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are semi-crystalline elastomers with a low melting point and high elongation at break, allowing for a wide range of applications in domestic, agricultural, industrial, and mainly medical fields. Utilizing low-cost cellulose hydrolyzed sugar as a carbon source and metabolic engineering to enhance synthesis in Pseudomonas putida is a promising strategy for commercializing mcl-PHAs, but little has been attempted to improve the utilization of glucose for synthesizing mcl-PHAs. In this study, a multi-pathway modification was performed to improve the utilization of substrate glucose and the synthesis capacity of PHAs. To enhance glucose metabolism to flow to acetyl-CoA, which is an important precursor of mcl-PHA, multiple genes in glucose metabolism were inactive (branch pathway and negative regulatory) and overexpressed (positive regulatory) in this study. The two genes, gcd (encoding glucose dehydrogenase) and gltA (encoding citrate synthase), involved in glucose peripheral pathways and TCA cycles were separately and jointly knocked out in Pseudomonas putida QSRZ6 (ΔphaZΔhsdR), and the mcl-PHA synthesis was improved in the mutants; particularly, the mcl-PHA titer of QSRZ603 (ΔgcdΔgltA) was increased by 33.7%. Based on the glucose branch pathway truncation, mcl-PHA synthesis was further improved with hexR-inactivation (encoding a negative regulator in glucose metabolism). Compared with QSRZ603 and QSRZ6, the mcl-PHA titer of QSRZ607 (ΔgcdΔgltAΔhexR) was increased by 62.8% and 117.5%, respectively. The mutant QSRZ609 was constructed by replacing the endogenous promoter of gltB encoding a transcriptional activator of the two-component regulatory system GltR/GltS with the ribosome subunit promoter P33. The final mcl-PHA content and titers of QSRZ609 reached 57.3 wt% and 2.5 g/L, an increase of and 20.9% and 27.3% over that of the parent strain QSRZ605 and an increase of 110.4% and 159.9% higher as compared to QSRZ6, respectively. The fermentation was optimized with a feeding medium in shaker flacks; then, the mcl-PHA contents and titer of QSRZ609 were 59.1 wt% and 6.8 g/L, respectively. The results suggest that the regulation from glucose to acetyl-CoA by polygenic modification is an effective strategy for enhancing mcl-PHA synthesis, and the mutants obtained in this study can be used as chassis to further increase mcl-PHA production.

“Being, Like, Their Parents Throughout Their Lifetime”—House Parents' Perceptions of Their Role in the Family‐Style Group Care

ABSTRACTBased on the concepts in Katz and Kahn's role theory model this qualitative research examines the role perception and experience of house parents in the family‐style group care, a type of out‐of‐home placement model for at‐risk children who cannot reside with their birth families. Semistructured interviews were conducted with 18 house parents (both men and women) to gain insights into their role perception and experience. The findings revolved around three central themes: motivation for choosing the role (search for meaning, previous exposure to the role and childhood experiences); role perception (parental and administrative); and experiencing the role, in terms of positive and negative emotions. The theoretical significance of this research lies in understanding the unique role perception of house parents, distinct from the corporate world. In comprehending the role of house parents, its nature and its impact on the well‐being of individuals in this role, social workers can improve house parent training and contribute to the mental well‐being of children growing up in these settings.

Proteomics and Metabolomics Study on the Responses of Sertoli Cells Infected With Brucella and Its bvfA-Deletion Strains.

To investigate the potential effects of BvfA in reproductive system damage caused by Brucella. Brucella intracellular multiplication ability was determined by a gentamicin protection assay; the LDH method was used to determine the lethal effect of Brucella on TM4 cells. Afterward, Label-free proteomics and LC-MS/MS metabolomics assays were combined to reveal differential abundant proteins and metabolites of TM4 cells infected with bvfA-deletion strains and parental strains. Finally, PRM mass spectrometry and western blot analysis were carried out to confirm differential expression of proteins. This report demonstrated that bvfA-deletion strains failed to invade TM4 cells and reconstitution of invasion when a strain with gene bvfA was reintroduced to the deletion strain in 3 h. The bvfA-deletion exhibited weakened intracellular multiplication compared with parental strains in TM4 cells in 12 h; however, the death rate of TM4 cells infected with bvfA-deletion strains was higher than that of TM4 cells infected with parental strains. Combined proteomics and metabolomics analyses revealed that the differential abundant proteins and metabolites in TM4 cells infected with bvfA-deletion and parental strains mainly involved the mineral absorption-related pathway, NADH:ubiquinone oxidoreductase subunit-related mitochondrial respiratory signaling pathway, and sphingolipid signaling pathway of TM4 cells. These three signaling pathways were involved in expression changes of TRPM6/7, STEAP1, Gnaq, Trp53, Pbk, Tns2, Akt2, and the NADH:ubiquinone oxidoreductase subunit, as well as content changes of l-Valine, l-Isoleucine, l-Methionine, PC, PE DG, and SM metabolites. These results indicated that BvfA of Brucella abortus S19 affected the above proteins and metabolites in TM4 cells.

Helping the Noncompliant Child and Child Behavior Outcomes: An Exploratory Examination of Financial Strain.

Theoretical models and empirical research have highlighted the impact of economic disadvantage on children's psychosocial development broadly and the onset, maintenance, and treatment of early-onset (3-8 years) behavior disorders (BDs) more specifically. In the context of intervention, evidence suggests that economic disadvantage may pose risk for diminished parent-mediated treatment efficacy (e.g., Behavioral Parent Training [BPT]) given its impact on salient factors in the family system. Though, studies have shown significant variability in BPT outcomes within families experiencing economic disadvantage, suggesting that additional influences may further contribute to disparities in the trajectory of treatment and maintenance of treatment gains for this population. To address this gap in existing knowledge, financial strain, or the inability to meet financial needs, was examined in families (N = 54) of young children (3-8 years old) with low-income and clinically elevated behavior problems participating in one BPT program, Helping the Noncompliant Child (HNC). Results demonstrated that families who experienced greater levels of financial strain prior to engaging in HNC exhibited diminished maintenance of parent reported child behavior gains following treatment. Financial strain did not significantly influence rate of change or maintenance of treatment gains for HNC clinician-coded child compliance. Clinical implications and directions for future research are discussed. ClinicalTrials.gov Identifier: NCT02191956, registered on 6/18/2014.

Family therapy and systemic interventions for child‐focussed problems: The evidence base

AbstractThis 25th anniversary review updates previous similar papers published in JFT in 2000, 2009, 2014 and 2019. It presents evidence from meta‐analyses and systematic reviews for the effectiveness of systemic interventions for families of young people with common mental and physical health problems and other difficulties where children are the primary focus of concern. In this context, systemic interventions include both family therapy and other family‐based approaches such as parent training, or parent‐implemented interventions. There is now a substantial evidence base supporting the effectiveness of systemic interventions either alone or as part of multimodal programmes for infant mental health and sleep and feeding problems in infancy; recovery from child abuse and neglect; externalising and internalising problems; eating disorders; somatic problems; and psychosis.

The role of cydB gene in the biofilm formation by Campylobacter jejuni

Campylobacter jejuni is a major cause of food- and water-borne bacterial infections in humans. A key factor helping bacteria to survive adverse environmental conditions is biofilm formation ability. Nonetheless, the molecular basis underlying biofilm formation by C. jejuni remains poorly understood. Around thirty genes involved in the regulation and dynamics of C. jejuni biofilm formation have been described so far. We applied random transposon mutagenesis to identify new biofilm-associated genes in C. jejuni strain 81–176. Of 1350 mutants, twenty-four had a decreased ability to produce biofilm compared to the wild-type strain. Some mutants contained insertions in genes previously reported to affect the biofilm formation process. The majority of identified genes encoded hypothetical proteins. In the library of EZ-Tn5 insertion mutants, we found the cydB gene associated with respiration that was not previously linked with biofilm formation in Campylobacter. To study the involvement of the cydB gene in biofilm formation, we constructed a non-marked deletion cydB mutant together with a complemented mutant. We found that the cydB deletion-mutant formed a weaker biofilm of loosely organized structure and lower volume than the parent strain. In the present study, we demonstrated the role of the cydB gene in biofilm formation by C. jejuni.

Improvement of succinate production from methane by combining rational engineering and laboratory evolution in Methylomonas sp. DH-1

Recently, methane has been considered a next-generation carbon feedstock due to its abundance and it is main component of shale gas and biogas. Methylomonas sp. DH-1 has been evaluated as a promising industrial bio-catalyst candidate. Succinate is considered one of the top building block chemicals in the agricultural, food, and pharmaceutical industries. In this study, succinate production by Methylomonas sp. DH-1 was improved by combining adaptive laboratory evolution (ALE) technology with genetic engineering in the chromosome of Methylomonas sp. DH-1, such as deletion of bypass pathway genes (succinate dehydrogenase and succinate semialdehyde dehydrogenase) or overexpression of genes related with succinate production (citrate synthase, pyruvate carboxylase and phosphoenolpyruvate carboxylase). Through ALE, the maximum consumption rate of substrate gases (methane and oxygen) and the duration maintaining high substrate gas consumption rates was enhanced compared to those of the parental strain. Based on the improved methane consumption, cell growth (OD600) increased more than twice, and the succinate titer increased by ~ 48% from 218 to 323 mg/L. To prevent unwanted succinate consumption, the succinate semialdehyde dehydrogenase gene was deleted from the genome. The first enzyme of TCA cycle (citrate synthase) was overexpressed. Pyruvate carboxylase and phosphoenolpyruvate carboxylase, which produce oxaloacetate, a substrate for citrate synthase, were also overproduced by a newly identified strong promoter. The new strong promoter was screened from RNA sequencing data. When these modifications were combined in one strain, the maximum titer (702 mg/L) was successfully improved by more than three times. This study demonstrates that successful enhancement of succinic acid production can be achieved in methanotrophs through additional genetic engineering following adaptive laboratory evolution.

Cyber Sex Crimes Targeting Children and Adolescents in South Korea: Incidents and Legal Challenges

This review paper addresses the growing and increasingly sophisticated issue of cyber sexual crimes targeting children and adolescents. It explores specific examples of various sexual offenses, analyzes the limitations of current legal frameworks, and offers practical recommendations for prevention. As one of the world’s most advanced digital societies, South Korea has witnessed a significant rise in such crimes. These incidents are classified into clear criminal acts, tactics used to lure minors, and occurrences within virtual environments, all of which should be integral to educational programs for children and parents. This study also examines the UK’s Online Safety Act, recognized as a leading model in combating online sexual offenses, and highlights the deficiencies in South Korean law. Given that these crimes often extend into the offline world, exploit vulnerable groups with increasing subtlety, and are challenging for individuals to counteract alone, there is a critical need for specialized education for minors, metaverse training for parents, and the enhancement of both legal measures and international cooperation in this area.

Simultaneous saccharification and fermentation for d-lactic acid production using a metabolically engineered Escherichia coli adapted to high temperature

BackgroundEscherichia coli JU15 is a metabolically engineered strain capable to metabolize C5 and C6 sugars with a high yield of d-lactic acid production at its optimal growth temperature (37 °C). The simultaneous saccharification and fermentation process allow to use lignocellulosic biomass as a cost-effective and high-yield strategy. However, this process requires microorganisms capable of growth at a temperature close to 50 °C, at which the activity of cellulolytic enzymes works efficiently.ResultsThe thermotolerant strain GT48 was generated by adaptive laboratory evolution in batch and chemostat cultures under temperature increments until 48 °C. The strain GT48 was able to grow and ferment glucose to d-lactate at 47 °C. It was found that a pH of 6.3 conciliated with GT48 growth and cellulase activity of a commercial cocktail. Hence, this pH was used for the SSF of a diluted acid-pretreated corn stover (DAPCS) at a solid load of 15% (w/w), 15 FPU/g-DAPCS, and 47 °C. Under such conditions, the strain GT48 exhibited remarkable performance, producing d-lactate at a level of 1.41, 1.42, and 1.48-fold higher in titer, productivity, and yield, respectively, compared to parental strain at 45 °C.ConclusionsIn general, our results show for the first time that a thermal-adapted strain of E. coli is capable of being used in the simultaneous saccharification and fermentation process without pre-saccharification stage at high temperatures.