Journal of Microbiology

Journal Articles

Characterization and Comparative Genomic Analysis of vB_BceM_CEP1: A Novel Temperate Bacteriophage Infecting Burkholderia cepacia Complex.: Momen Askoura, Eslam K Fahmy, Safya E Esmaeel, Wael A H Hegazy, Aliaa Abdelghafar; J. Microbiol. 2024;62(11):1035-1055. Published online November 18, 2024; DOI: https://doi.org/10.1007/s12275-024-00185-2

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Abstract: The increasing prevalence of multidrug-resistant bacteria imminently threatens public health and jeopardizes nearly all aspects of modern medicine. The Burkholderia cepacia complex (Bcc) comprises Burkholderia cepacia and the related species of Gram-negative bacteria. Members of the Bcc group are opportunistic pathogens responsible for various chronic illnesses, including cystic fibrosis and chronic granulomatous disease. Phage therapy is emerging as a potential solution to combat the antimicrobial resistance crisis. In this study, a temperate phage vB_BceM_CEP1 was isolated from sewage and fully characterized. Transmission electron microscopy indicated that vB_BceM_CEP1 belongs to the family Peduoviridae. The isolated phage demonstrated enhanced environmental stability and antibiofilm potential. One-step growth analysis revealed a latent period of 30 min and an average burst size of 139 plaque-forming units per cell. The genome of vB_BceM_CEP1 consists of 32,486 bp with a GC content of 62.05%. A total of 40 open reading frames were annotated in the phage genome, and none of the predicted genes was annotated as tRNA. Notably, genes associated with antibiotic resistance, host virulence factors, and toxins were absent from the vB_BceM_CEP1 genome. Based on its unique phenotype and phylogeny, the isolated phage vB_BceM_CEP1 is classified as a new temperate phage with lytic activity. The findings of this study enhance our understanding of the diversity of Bcc phages.

The Gut Microbiota Mediates the Protective Effects of Spironolactone on Myocardial Infarction.: Lu Li, Jian-Yong Sun, Yu-Lin Li, Shi-Wei Zhu, Sheng-Zhong Duan; J. Microbiol. 2024;62(10):883-895. Published online September 3, 2024; DOI: https://doi.org/10.1007/s12275-024-00164-7

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Abstract: Myocardial infarction (MI) is a type of cardiovascular disease that influences millions of human beings worldwide and has a great rate of mortality and morbidity. Spironolactone has been used as a critical drug for the treatment of cardiac failure and it ameliorates cardiac dysfunction post-MI. Despite these findings, whether there is a relationship between the therapeutic effects of spironolactone and the gut microorganism after MI has not been determined. In our research, we used male C57BL/6 J mice to explore whether the gut microbiota mediates the beneficial function of spironolactone after myocardial infarction. We demonstrated that deletion of the gut microbiota eliminated the beneficial function of spironolactone in MI mice, displaying exacerbated cardiac dysfunction, cardiac infarct size. In addition, the gut microbiota was altered by spironolactone after sham or MI operation in mice. We also used male C57BL/6 J mice to investigate the function of a probiotic in the myocardial infarction. In summary, our findings reveal a precious role of the gut flora in the therapeutic function of spironolactone on MI.

Delineating the Acquired Genetic Diversity and Multidrug Resistance in Alcaligenes from Poultry Farms and Nearby Soil.: Abhilash Bhattacharjee, Anil Kumar Singh; J. Microbiol. 2024;62(7):511-523. Published online June 21, 2024; DOI: https://doi.org/10.1007/s12275-024-00129-w

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Abstract: Alcaligenes faecalis is one of the most important and clinically significant environmental pathogens, increasing in importance due to its isolation from soil and nosocomial environments. The Gram-negative soil bacterium is associated with skin endocarditis, bacteremia, dysentery, meningitis, endophthalmitis, urinary tract infections, and pneumonia in patients. With emerging antibiotic resistance in A. faecalis, it has become crucial to understand the origin of such resistance genes within this clinically significant environmental and gut bacterium. In this research, we studied the impact of antibiotic overuse in poultry and its effect on developing resistance in A. faecalis. We sampled soil and faecal materials from five poultry farms, performed whole genome sequencing & analysis and identified four strains of A. faecalis. Furthermore, we characterized the genes in the genomic islands of A. faecalis isolates. We found four multidrug-resistant A. faecalis strains that showed resistance against vancomycin (MIC >1000 μg/ml), ceftazidime (50 μg/ml), colistin (50 μg/ml) and ciprofloxacin (50 μg/ml). From whole genome comparative analysis, we found more than 180 resistance genes compared to the reference sequence. Parts of our assembled contigs were found to be similar to different bacteria which included pbp1A and pbp2 imparting resistance to amoxicillin originally a part of Helicobacter and Bordetella pertussis. We also found the Mycobacterial insertion element IS6110 in the genomic islands of all four genomes. This prominent insertion element can be transferred and induce resistance to other bacterial genomes. The results thus are crucial in understanding the transfer of resistance genes in the environment and can help in developing regimes for antibiotic use in the food and poultry industry.

Review

Structural Insights into the Lipopolysaccharide Transport (Lpt) System as a Novel Antibiotic Target.: Yurim Yoon, Saemee Song; J. Microbiol. 2024;62(4):261-275. Published online May 31, 2024; DOI: https://doi.org/10.1007/s12275-024-00137-w

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Abstract: Lipopolysaccharide (LPS) is a critical component of the extracellular leaflet within the bacterial outer membrane, forming an effective physical barrier against environmental threats in Gram-negative bacteria. After LPS is synthesized and matured in the bacterial cytoplasm and the inner membrane (IM), LPS is inserted into the outer membrane (OM) through the ATP-driven LPS transport (Lpt) pathway, which is an energy-intensive process. A trans-envelope complex that contains seven Lpt proteins (LptA-LptG) is crucial for extracting LPS from the IM and transporting it across the periplasm to the OM. The last step in LPS transport involves the mediation of the LptDE complex, facilitating the insertion of LPS into the outer leaflet of the OM. As the Lpt system plays an essential role in maintaining the impermeability of the OM via LPS decoration, the interactions between these interconnected subunits, which are meticulously regulated, may be potential targets for the development of new antibiotics to combat multidrug-resistant Gram-negative bacteria. In this review, we aimed to provide an overview of current research concerning the structural interactions within the Lpt system and their implications to clarify the function and regulation of LPS transport in the overall process of OM biogenesis. Additionally, we explored studies on the development of therapeutic inhibitors of LPS transport, the factors that limit success, and future prospects.

Journal Articles

Coumarin-based combined computational study to design novel drugs against Candida albicans: Akhilesh Kumar Maurya , Nidhi Mishra; J. Microbiol. 2022;60(12):1201-1207. Published online November 10, 2022; DOI: https://doi.org/10.1007/s12275-022-2279-5

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Abstract: Candida species cause the most prevalent fungal illness, candidiasis. Candida albicans is known to cause bloodstream infections. This species is a commensal bacterium, but it can cause hospital–acquired diseases, particularly in COVID-19 patients with impaired immune systems. Candida infections have increased in patients with acute respiratory distress syndrome. Coumarins are both naturally occurring and synthetically produced. In this study, the biological activity of 40 coumarin derivatives was used to create a three-dimensional quantitative structure activity relationship (3D-QSAR) model. The training and test minimum inhibitory concentration values of C. albicans active compounds were split, and a regression model based on statistical data was established. This model served as a foundation for the creation of coumarin derivative QSARs. This is a unique way to create new therapeutic compounds for various ailments. We constructed novel structural coumarin derivatives using the derived QSAR model, and the models were confirmed using molecular docking and molecular dynamics simulation.

Description of Flavobacterium cyclinae sp. nov. and Flavobacterium channae sp. nov., isolated from the intestines of Cyclina sinensis (Corb shell) and Channa argus (Northern snakehead): Seomin Kang , Jae-Yun Lee , Jeong Eun Han , Yun-Seok Jeong , Do-Hun Gim , Jin-Woo Bae; J. Microbiol. 2022;60(9):890-898. Published online June 22, 2022; DOI: https://doi.org/10.1007/s12275-022-2075-2

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Abstract: Two novel bacterial strains, KSM-R2A25T and KSM-R2A30T, were isolated from intestines of Cyclina sinensis (corb shell) and Channa argus (northern snakehead), respectively. Both specimens were collected in Korea. The strains were Gramstain- negative, non-motile, and strictly aerobic. According to phylogenetic analyses based on 16S rRNA gene sequences, strains belonged to the genus Flavobacterium within the family Flavobacteriaceae. 16S rRNA gene sequences of strains KSMR2A25T and KSM-R2A30T were closely related to Flavobacterium cucumis DSM 18830T and Flavobacterium aquaticum JC164T with sequence similarities of 97.77% and 98.54%, respectively. Further genomic analyses including reconstruction of the UBCG tree and overall genome-related indices suggested them as novel species of the genus Flavobacterium. Both strains contained menaquinone with six isoprene units (MK-6) as a major isoprenoid quinone and iso-C15:1 G, iso- C15:0, and iso-C16:0 as major cellular fatty acids. The major polar lipid in both strains was phosphatidylethanolamine. The genomic G + C contents of strains KSM-R2A25T and KSMR2A30T were 31.7 and 31.9%, respectively. Based on the polyphasic taxonomic study presented here, strains KSM-R2A25T and KSM-R2A30T represent novel species of the genus Flavobacterium, for which the names Flavobacterium cyclinae sp. nov and Flavobacterium channae sp. nov are proposed. The type strains of F. cyclinae sp. nov and F. channae sp. nov are KSM-R2A25T (= KCTC 82978T = JCM 34997T) and KSMR2A30T (= KCTC 82979T = JCM 34998T), respectively.

Eradication of drug-resistant Acinetobacter baumannii by cell-penetrating peptide fused endolysin: Jeonghyun Lim , Jaeyeon Jang , Heejoon Myung , Miryoung Song; J. Microbiol. 2022;60(8):859-866. Published online May 25, 2022; DOI: https://doi.org/10.1007/s12275-022-2107-y

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Abstract: Antimicrobial agents targeting peptidoglycan have shown successful results in eliminating bacteria with high selective toxicity. Bacteriophage encoded endolysin as an alternative antibiotics is a peptidoglycan degrading enzyme with a low rate of resistance. Here, the engineered endolysin was developed to defeat multiple drug-resistant (MDR) Acinetobacter baumannii. First, putative endolysin PA90 was predicted by genome analysis of isolated Pseudomonas phage PBPA. The His-tagged PA90 was purified from BL21(DE3) pLysS and tested for the enzymatic activity using Gram-negative pathogens known for having a high antibiotic resistance rate including A. baumannii. Since the measured activity of PA90 was low, probably due to the outer membrane, cell-penetrating peptide (CPP) DS4.3 was introduced at the N-terminus of PA90 to aid access to its substrate. This engineered endolysin, DS-PA90, completely killed A. baumannii at 0.25 μM, at which concentration PA90 could only eliminate less than one log in CFU/ml. Additionally, DS-PA90 has tolerance to NaCl, where the ~50% of activity could be maintained in the presence of 150 mM NaCl, and stable activity was also observed with changes in pH or temperature. Even MDR A. baumannii strains were highly susceptible to DS-PA90 treatment: five out of nine strains were entirely killed and four strains were reduced by 3–4 log in CFU/ml. Consequently, DS-PA90 could protect waxworm from A. baumannii-induced death by ~70% for ATCC 17978 or ~44% for MDR strain 1656-2 infection. Collectively, our data suggest that CPP-fused endolysin can be an effective antibacterial agent against Gramnegative pathogens regardless of antibiotics resistance mechanisms.

Assessing the microcystins concentration through optimized protein phosphatase inhibition assay in environmental samples: Kyoung-Hee Oh , Kung-Min Beak , Yuna Shin , Young-Cheol Cho; J. Microbiol. 2022;60(6):602-609. Published online April 30, 2022; DOI: https://doi.org/10.1007/s12275-022-2020-4

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Abstract: Protein phosphatase (PPase) inhibition assay (PPIA) is widely used to analyze the concentration of microcystins (MCs) because it is comparatively less expensive and faster than other assays. This study aimed to optimize the PPIA by determining a suitable reaction terminator and an optimal methanol concentration in the sample. The most suitable reaction time was 90 min, with the corresponding methanol concentration in the sample being 15% or less. When p-nitrophenyl phosphate (pNPP) was used as a substrate, copper chloride solution was suitably used as a reaction terminator, and when 4- methylumbelliferyl phosphate (MUP) was used, a glycine buffer not only increased the measurement sensitivity of the reaction product but also terminated the enzymatic reaction. When PPase 1 and MUP were used as an enzyme and a substrate, respectively, the limit of quantitation for MC-leucine/ arginine (LR) was 0.02 μg/L, whereas it was 0.1 μg/L when pNPP was used as a substrate. The proposed method facilitated the measurement of MC-LR concentration without additional pretreatments, such as concentration or purification; therefore, this method was suitable and feasible for the continuous monitoring of MCs in drinking water.

Characterization of components of a reducing system for SoxR in the cytoplasmic membrane of Escherichia coli: Kang-Lok Lee , Kyung-Chang Lee , Joon-Hee Lee , Jung-Hye Roe; J. Microbiol. 2022;60(4):387-394. Published online March 28, 2022; DOI: https://doi.org/10.1007/s12275-022-1667-1

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Abstract: A reducing system of SoxR, a regulator of redox-active molecules, was identified as rsxABCDGE gene products and RseC in Escherichia coli through genetic studies. We found that ApbE was an additional component of the reducer system. Bacterial two hybrid analysis revealed that these proteins indeed had multiple interactions among themselves. RseC and RsxB formed the core of the complex, interacting with more than five other components. RsxC, the only cytoplasmic component of the system, interacted with SoxR. It might be linked with the rest of the complex via RsxB. Membrane fractions containing the wild type complex but not the mutant complex reduced purified SoxR using NADH as an electron source. These results suggest that Rsx genes, RseC, and ApbE can form a complex using NAD(P)H to reduce SoxR.

Review

Coordinated regulation of interferon and inflammasome signaling pathways by SARS-CoV-2 proteins: Na-Eun Kim , Yoon-Jae Song; J. Microbiol. 2022;60(3):300-307. Published online January 28, 2022; DOI: https://doi.org/10.1007/s12275-022-1502-8

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5 Citations

Abstract: Type I and III interferons (IFNs) and the nucleotide-binding domain (NBD) leucine-rich repeat (LRR)-containing receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome play pivotal roles in the pathogenesis of SARS-CoV-2. While optimal IFN and inflammasome responses are essential for limiting SARS-CoV-2 infection, aberrant activation of these innate immune responses is associated with COVID-19 pathogenesis. In this review, we focus our discussion on recent findings on SARS-CoV-2-induced type I and III IFNs and NLRP3 inflammasome responses and the viral proteins regulating these mechanisms.

Journal Articles

The synergy effect of arbuscular mycorrhizal fungi symbiosis and exogenous calcium on bacterial community composition and growth performance of peanut (Arachis hypogaea L.) in saline alkali soil: Dunwei Ci , Zhaohui Tang , Hong Ding , Li Cui , Guanchu Zhang , Shangxia Li , Liangxiang Dai , Feifei Qin , Zhimeng Zhang , Jishun Yang , Yang Xu; J. Microbiol. 2021;59(1):51-63. Published online November 17, 2020; DOI: https://doi.org/10.1007/s12275-021-0317-3

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18 Citations

Abstract: Peanut (Arachis hypogaea. L) is an important oil seed crop. Both arbuscular mycorrhizal fungi (AMF) symbiosis and calcium (Ca2+) application can ameliorate the impact of saline soil on peanut production, and the rhizosphere bacterial communities are also closely correlated with peanut salt tolerance; however, whether AMF and Ca2+ can withstand high-salinity through or partially through modulating rhizosphere bacterial communities is unclear. Here, we used the rhizosphere bacterial DNA from saline alkali soil treated with AMF and Ca2+ alone or together to perform high-throughput sequencing of 16S rRNA genes. Taxonomic analysis revealed that AMF and Ca2+ treatment increased the abundance of Proteobacteria and Firmicutes at the phylum level. The nitrogenfixing bacterium Sphingomonas was the dominant genus in these soils at the genus level, and the soil invertase and urease activities were also increased after AMF and Ca2+ treatment, implying that AMF and Ca2+ effectively improved the living environment of plants under salt stress. Moreover, AMF combined with Ca2+ was better than AMF or Ca2+ alone at altering the bacterial structure and improving peanut growth in saline alkali soil. Together, AMF and Ca2+ applications are conducive to peanut salt adaption by regulating the bacterial community in saline alkali soil.

Oecophyllibacter saccharovorans gen. nov. sp. nov., a bacterial symbiont of the weaver ant Oecophylla smaragdina: Kah-Ooi Chua , Wah-Seng See-Too , Jia-Yi Tan , Sze-Looi Song , Hoi-Sen Yong , Wai-Fong Yin , Kok-Gan Chan; J. Microbiol. 2020;58(12):988-997. Published online October 23, 2020; DOI: https://doi.org/10.1007/s12275-020-0325-8

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Abstract: In this study, bacterial strains Ha5T, Ta1, and Jb2 were isolated from different colonies of weaver ant Oecophylla smaragdina. They were identified as bacterial symbionts of the ant belonging to family Acetobacteraceae and were distinguished as different strains based on distinctive random-amplified polymorphic DNA (RAPD) fingerprints. Cells of these bacterial strains were Gram-negative, rod-shaped, aerobic, non-motile, catalase-positive and oxidase-negative. They were able to grow at 15–37°C (optimum, 28–30°C) and in the presence of 0–1.5% (w/v) NaCl (optimum 0%). Their predominant cellular fatty acids were C18:1 ω7c, C16:0, C19:0 ω8c cyclo, C14:0, and C16:0 2-OH. Strains Ha5T, Ta1, and Jb2 shared highest 16S rRNA gene sequence similarity (94.56–94.63%) with Neokomagataea tanensis NBRC106556T of family Acetobacteraceae. Both 16S rRNA gene sequence-based phylogenetic analysis and core gene-based phylogenomic analysis placed them in a distinct lineage in family Acetobacteraceae. These bacterial strains shared higher than species level thresholds in multiple overall genome-relatedness indices which indicated that they belonged to the same species. In addition, they did not belong to any of the current taxa of Acetobacteraceae as they had low pairwise average nucleotide identity (< 71%), in silico DNA-DNA hybridization (< 38%) and average amino acid identity (< 67%) values with all the type members of the family. Based on these results, bacterial strains Ha5T, Ta1, and Jb2 represent a novel species of a novel genus in family Acetobacteraceae, for which we propose the name Oecophyllibacter saccharovorans gen. nov. sp. nov., and strain Ha5T as the type strain.

In vitro disinfection efficacy and clinical protective effects of common disinfectants against acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio isolates in Pacific white shrimp Penaeus vannamei: Peizhuo Zou , Qian Yang , Hailiang Wang , Guosi Xie , Zhi Cao , Xing Chen , Wen Gao , Jie Huang; J. Microbiol. 2020;58(8):675-686. Published online July 27, 2020; DOI: https://doi.org/10.1007/s12275-020-9537-1

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Abstract: Acute hepatopancreatic necrosis disease (AHPND) is one of the most significant bacterial diseases in global shrimp culture, causing severe economic losses. In the present study, we carried out in vitro antimicrobial tests to investigate the disinfection efficacy of 14 common disinfectants toward different AHPND-causing Vibrio spp., including eight isolates of V. parahaemolyticus, four isolates of V. campbellii, and one isolate of V. owensii. Polyhexamethylene biguanidine hydrochloride (PHMB) was revealed to possess the strongest inhibitory activity. Through analyzing and evaluating the results of antimicrobial tests and acute toxicity test, we selected PHMB and hydrogen peroxide (H2O2) for further clinical protection test. Clinical manifestations indicated that both PHMB (2 mg/L and 4 mg/L) and H2O2 (12 mg/L) could effectively protect juvenile Penaeus vannamei from the infection of V. parahaemolyticus isolate Vp362 at 106 CFU/ml, and the survival rate was over 80%. When the bacterial concentration was reduced to 105 CFU/ml, 104 CFU/ml, and 103 CFU/ml, the survival rate after treated by 1 mg/L PHMB was 64.44%, 93.33%, and 100%, respectively. According to the results, PHMB and H2O2 showed a lower toxicity while a better protection activity, particularly against a lower concentration of the pathogens. Therefore, these two disinfectants are proved to be promising disinfectants that can be applied to prevent and control AHPND in shrimp culture. Moreover, the methods of this study also provided valuable information for the prevention of other important bacterial diseases and suggested a reliable means for screening potential drugs in aquaculture.

The relationship between bacterial diversity and organic carbon mineralization in soft rock and sand compound soil: Zhen Guo , Juan Li , Lei Ge , Chenxi Yang , Jichang Han; J. Microbiol. 2020;58(9):750-760. Published online July 24, 2020; DOI: https://doi.org/10.1007/s12275-020-0130-4

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Abstract: The soil organic carbon (SOC) mineralization rate in sandy soil plays an important role in improving soil quality, and a research is needed to determine management practices that optimize the mineralization rate. When sandy soil is improved by adding soft rock, the specific promotion process of bacterium to SOC mineralization remain unclear. To investigate these mechanisms, we selected four treatments with soft rock to sand volume ratios of 0:1 (CK), 1:5 (C1), 1:2 (C2) and 1:1 (C3) to study. The mineralization rate of organic carbon was measured using the lye absorption method. Highthroughput sequencing and scanning electron microscopy were used to determine the bacterial community structure and soil microstructure, respectively. The results showed that the organic carbon content of the sandy soil increased significantly (182.22–276.43%) after using the soft rock treatments. The SOC mineralization rate could be divided into two stages: a rapid decline during days 1–8 and a slow decline during days 8–60. With increased incubation time, the intensity of the cumulative release of organic carbon gradually weakened. Compared with the CK treatment, the SOC mineralization accumulation (Ct) and the potential mineralizable organic carbon content (C0) in the C1, C2, and C3 treatments increased significantly, by 106.98–225.94% and 112.22– 254.08%, respectively. The cumulative mineralization rate (Cr) was 18.11% and 21.38% smaller with treatments C2 and C3, respectively. The SOC mineralization rate constant (k) decreased significantly after the addition of soft rock, while the half-turnover period (Th) changed inversely with k. Compared with the CK treatment, the number of gene copies of the soil bacteria increased by 15.38–272.53% after adding soft rock, with the most significant increase in treatment C3. The bacterial diversity index also increased significantly under treatment C3. The three dominant bacteria were Proteobacteria, Actinobacteria, and Chloroflexi. The correlation between Cr and one of the non-dominant bacteria, Firmicutes, was large, and the bacteria had a significant positive correlation with k. At the same time, the abundance of Firmicutes under treatments C2 and C3 was small. As the proportion of soft rock increased, the soil particles changed from point contact to surface contact, and the adhesion on the surface of the particles gradually increased. Results from this study show that the retention time of SOC can be increased and the carbon sequestration effect is better when the ratio of soft rock to sand is set to 1:2.

The effects of deletion of cellobiohydrolase genes on carbon source-dependent growth and enzymatic lignocellulose hydrolysis in Trichoderma reesei: Meibin Ren , Yifan Wang , Guoxin Liu , Bin Zuo , Yuancheng Zhang , Yunhe Wang , Weifeng Liu , Xiangmei Liu , Yaohua Zhong; J. Microbiol. 2020;58(8):687-695. Published online June 10, 2020; DOI: https://doi.org/10.1007/s12275-020-9630-5

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Abstract: The saprophytic fungus Trichoderma reesei has long been used as a model to study microbial degradation of lignocellulosic biomass. The major cellulolytic enzymes of T. reesei are the cellobiohydrolases CBH1 and CBH2, which constitute more than 70% of total proteins secreted by the fungus. However, their physiological functions and effects on enzymatic hydrolysis of cellulose substrates are not sufficiently elucidated. Here, the cellobiohydrolase-encoding genes cbh1 and cbh2 were deleted, individually or combinatively, by using an auxotrophic marker-recycling technique in T. reesei. When cultured on media with different soluble carbon sources, all three deletion strains (Δcbh1, Δcbh2, and Δcbh1Δcbh2) exhibited no dramatic variation in morphological phenotypes, but their growth rates increased apparently when cultured on soluble cellulase-inducing carbon sources. In addition, Δcbh1 showed dramatically reduced growth and Δcbh1Δcbh2 could hardly grew on microcrystalline cellulose (MCC), whereas all strains grew equally on sodium carboxymethyl cellulose (CMC-Na), suggesting that the influence of the CBHs on growth was carbon source-dependent. Moreover, five representative cellulose substrates were used to analyse the influence of the absence of CBHs on saccharification efficiency. CBH1 deficiency significantly affected the enzymatic hydrolysis rates of various cellulose substrates, where acid pre-treated corn stover (PCS) was influenced the least. CBH2 deficiency reduced the hydrolysis of MCC, PCS, and acid pre-treated and delignified corncob but improved the hydrolysis ability of filter paper. These results demonstrate the specific contributions of CBHs to the hydrolysis of different types of biomass, which could facilitate the development of tailor-made strains with highly efficient hydrolysis enzymes for certain biomass types in the biofuel industry.

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