Exploring the tolerance of marine yeast to inhibitory compounds for improving bioethanol production

Greetham, Darren; Zaky, Abdelrahman Saleh; Du, Chenyu

doi:10.1039/c9se00029a

Cited by 30 publications

(25 citation statements)

References 40 publications

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“…Furfural affected conidial germination and subsequent colony development in a dose-dependent manner with an IC 50 ~ 12.5 mM, as measured 20 h post inoculation (Additional file 1: Figure S1A). The inhibitory value we measured was similar to the IC 50 of 16 mM measured for S. cerevisiae [38].…”

Section: Resultssupporting

confidence: 85%

“…In this study, we focused on the ascomycete fungus N. crassa as a potential source of genes for yeast strain improvement. This fungus is able to grow on burned trees and is thus exposed to the inhibitory compound furfural in its natural habitat [25], even though the IC 50 for furfural was similar in N. crassa and yeast [38]. To understand the molecular and metabolic basis and to identify new genes involved in tolerance toward furfural in N. crassa, we used a combination of approaches, including RNA-seq, hypothesis-driven reverse genetics and random promotor insertional mutagenesis.…”

Section: Discussionmentioning

confidence: 99%

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Identification and manipulation of Neurospora crassa genes involved in sensitivity to furfural

Feldman

Kowbel

Cohen

et al. 2019

Biotechnol Biofuels

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Background Biofuels derived from lignocellulosic biomass are a viable alternative to fossil fuels required for transportation. Following plant biomass pretreatment, the furan derivative furfural is present at concentrations which are inhibitory to yeasts. Detoxification of furfural is thus important for efficient fermentation. Here, we searched for new genetic attributes in the fungus Neurospora crassa that may be linked to furfural tolerance. The fact that furfural is involved in the natural process of sexual spore germination of N. crassa and that this fungus is highly amenable to genetic manipulations makes it a rational candidate for this study. Results Both hypothesis-based and unbiased (random promotor mutagenesis) approaches were performed to identify N. crassa genes associated with the response to furfural. Changes in the transcriptional profile following exposure to furfural revealed that the affected processes were, overall, similar to those observed in Saccharomyces cerevisiae . N. crassa was more tolerant (by ~ 30%) to furfural when carboxymethyl cellulose was the main carbon source as opposed to sucrose, indicative of a link between carbohydrate metabolism and furfural tolerance. We also observed increased tolerance in a Δ cre - 1 mutant (CRE-1 is a key transcription factor that regulates the ability of fungi to utilize non-preferred carbon sources). In addition, analysis of aldehyde dehydrogenase mutants showed that ahd - 2 (NCU00378) was involved in tolerance to furfural as well as the predicted membrane transporter NCU05580 ( flr - 1 ), a homolog of FLR1 in S. cerevisiae . Further to the rational screening, an unbiased approach revealed additional genes whose inactivation conferred increased tolerance to furfural: (i) NCU02488, which affected the abundance of the non-anchored cell wall protein NCW-1 (NCU05137), and (ii) the zinc finger protein NCU01407. Conclusions We identified attributes in N. crassa associated with tolerance or degradation of furfural, using complementary research approaches. The manipulation of the genes involved in furan sensitivity can provide a means for improving the production of biofuel producing strains. Similar research approaches can be utilized in N. crassa and other filamentous fungi to identify additional attributes relevant to other furans or toxic chemicals.

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Section: Resultssupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Identification and manipulation of Neurospora crassa genes involved in sensitivity to furfural

Feldman

Kowbel

Cohen

et al. 2019

Biotechnol Biofuels

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“…Current industrial probiotic microbial strains are predominantly isolated from terrestrial environment. It has been reported that marine yeasts are phenotypically distinct for terrestrial yeasts and highly tolerant to growth inhibitors such as salt, acid, and temperature [71]. Marine microorganisms, especially marine yeasts, have shown interesting probiotic properties [72, 73].…”

Section: Discussionmentioning

confidence: 99%

Investigating the probiotic characteristics of four microbial strains with potential application in feed industry

Kim¹,

Bayo

Cha³

et al. 2019

PLoS ONE

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The present study aimed to evaluate the probiotic characteristics of certain microbial strains for potential use as feed additives. Three bacterial strains and a yeast previously isolated from different environments were investigated. The strains were subjected to molecular identification and established as Lactobacillus paracasei CP133, Lactobacillus plantarum CP134, Bacillus subtilis CP350 and Saccharomyces cerevisiae CP605. Lactobacillus sp. CP133 and CP134 exhibited antibiosis, antibiotic activity, and relative odor reduction ability. Bacillus subtilis CP350 was thermotolerant, reduced hydrogen sulfide gas and showed significant proteolytic activity, whereas Saccharomyces cerevisiae CP605 exhibited high acid and bile salt tolerance. In general, the isolates in this study demonstrated improved functional characteristics, particularly acid and bile tolerance and relative cell adhesion to HT-29 monolayer cell line. Results in this work provides multifunctional probiotic characteristics of the strains for potential development of probiotics and cleaning of the environment.

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“…The conventional method for producing BNC using glucose as carbon source is a high cost process and cannot be produced on large industrial scale. Therefore, production of BNC using cheap industrial waste as carbon, nitrogen and energy sources is required and has been extensively studied 20 – 23 . Coffee cherry husk extract (a byproduct from the coffee processing) 21 was used as less expensive source of carbon and a lot of other wastes like waste from fruit processing 22 .…”

Section: Introductionmentioning

confidence: 99%

Novel research on nanocellulose production by a marine Bacillus velezensis strain SMR: a comparative study

Abouelkheir

Kamara

Atia

et al. 2020

Sci Rep

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Bacterial nanocellulose (BNC) is a nanofibrillar polymer that possesses unique characteristics such as high chemical purity, mechanical strength, flexibility, and absorbency. In addition, different bacterial strains can form nanocellulose (NC) in multiple shapes and sizes. This study describes the first report of a marine Bacillus strain that is able to synthesize NC. The strain identified as B. velezensis SMR based on 16S rDNA sequencing, produced highly structured NC, as confirmed by X-ray diffraction (XRD) and Scanning Electron Microscopic Analysis (SEM). In Hestrin-Schramm (HS) medium, B. velezensis SMR produced twice the quantity of BNC in comparison to the reference strain, G. xylinus ATCC 10245. The ability of B. velezensis SMR to produce NC using different industrial waste materials as growth media was tested. Growth in Ulva seaweed extract supported a 2.5-fold increase of NC production by B. velezensis SMR and a threefold increase in nc production by G. xylinus ATCC 10245. As proof of principle for the usability of nc from B. velezensis SMR, we successfully fabricated a BNCbased polyvinyl alcohol hydrogel (BNC-PVA) system, a promising material used in different fields of application such as medicine, food, and agriculture. Bacterial nanocellulose (BNC), an extracellular produced structure, is considered a highly desirable biomaterial due to its superior qualities in comparison to other cellulose-containing structures. Compared to plant cellulose, nanofibril network of biocellulose possesses high water retaining capacity, degree of polymerization, chemical purity, high crystallinity, in vivo biocompatibility to be used as a scaffold in tissue engineering, and excellent mechanical properties 1,2. BNC production has been reported in both Gram-negative bacteria such as G. xylinus, Agrobacterium, Achromobacter, Aerobacter, Azotobacter, Pseudomonas, and Rhizobium, and Gram-positive bacteria such as Sarcina 3. Among the different BNC-producing bacteria, G. xylinus is the most commonly studied species 4. Synthesis of BNC is a complex process involving polymerization of glucose monomers and secretion of the complex cellulose structures to the external environment to create a three-dimensional microfibril and nanofibril network. During the fermentation process, bacteria either move freely in the media or attach to cellulose fibers, producing a highly swollen gel structure 5. Purification of NC from the culture medium involves the removal of bacterial cells and collection of the cellulose matrix from the cultural medium. This is a crucial step to ensure the quality of BNC and can be performed either by repeated washing using a hot sodium hydroxide solution, followed by water until reaching a neutral pH or by other methods, such as gamma radiation 6. While BNC-production by several bacterial species have been reported, it has never been shown that members of the genus Bacillus were able to produce NC. B. velezensis is a Gram-positive bacterium that has been extensively studied for its ability to induce plant growth-...

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Exploring the tolerance of marine yeast to inhibitory compounds for improving bioethanol production

Abstract: Inhibitor tolerance is one of the key challenges in lignocellulosic bioethanol production.

Cited by 30 publications

References 40 publications

Identification and manipulation of Neurospora crassa genes involved in sensitivity to furfural

Identification and manipulation of Neurospora crassa genes involved in sensitivity to furfural

Investigating the probiotic characteristics of four microbial strains with potential application in feed industry

Novel research on nanocellulose production by a marine Bacillus velezensis strain SMR: a comparative study

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