scholarly journals Rhodococcus as Biofactories for Microbial Oil Production

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4871
Author(s):  
Héctor M. Alvarez ◽  
Martín A. Hernández ◽  
Mariana P. Lanfranconi ◽  
Roxana A. Silva ◽  
María S. Villalba

Bacteria belonging to the Rhodococcus genus are frequent components of microbial communities in diverse natural environments. Some rhodococcal species exhibit the outstanding ability to produce significant amounts of triacylglycerols (TAG) (>20% of cellular dry weight) in the presence of an excess of the carbon source and limitation of the nitrogen source. For this reason, they can be considered as oleaginous microorganisms. As occurs as well in eukaryotic single-cell oil (SCO) producers, these bacteria possess specific physiological properties and molecular mechanisms that differentiate them from other microorganisms unable to synthesize TAG. In this review, we summarized several of the well-characterized molecular mechanisms that enable oleaginous rhodococci to produce significant amounts of SCO. Furthermore, we highlighted the ability of these microorganisms to degrade a wide range of carbon sources coupled to lipogenesis. The qualitative and quantitative oil production by rhodococci from diverse industrial wastes has also been included. Finally, we summarized the genetic and metabolic approaches applied to oleaginous rhodococci to improve SCO production. This review provides a comprehensive and integrating vision on the potential of oleaginous rhodococci to be considered as microbial biofactories for microbial oil production.

2021 ◽  
Vol 14 (4) ◽  
pp. 1992-2001
Author(s):  
Bothaina A. Alaidaroos

In the past two decades, phenolic compounds have had different applications, however their use in densification has increased considerably due to Covid 19. Discharge of these dangerous materials is highly toxic and causes risk and severe problems to the environment and health of human and animals, in addition to it being harmful to the aquatic life. Phenol degradation is very important due to high toxicity and stability. The aim of this study is to isolate phenol-degrading aerobic bacteria from hydrocarbon contaminated soil or wastewater, collected from the industrial area of Jeddah. Minimal medium containing phenol as carbon source was used to isolate different bacteria. About 30 actinomycete isolates were obtained, purified and preserved on Starch nitrate. Out of 30 isolates, eight isolates (27%) grow well in medium containing 0.1% phenol. After growing in broth medium, isolate BA4 and isolate BA8 were very active in phenol degradation. Growth and phenol degradation was measured in liquid medium for the two isolates. Morphological and physiological characters of these isolates were detected using different methods. Using molecular methods, they were belonging to a genus of actinomycetes. They were identified as Streptomyces flavabus BA4 and Streptomyces sp. BA8.The effects of some growth factors on growth and phenol degradation were determined. Growth was measured by dry weight (mg/l) while phenol degradation was detected by assaying the residual phenol concentration. The presence of electron donors such as glucose, starch, glycine, peptone, and Na acetate affect both growth and phenol degradation. It was clear that addition of 1 g/l peptone enhanced both growth and phenol degradation. The isolate use phenol and its derivatives m-cresol and o-cresol as carbon sources and addition of vitamin B complex increased the bacterial growth. In conclusion, phenol degradation was detected by actinobacteria and was affected by some physical and biochemical factors. It was noticed that optimization of growth conditions enhanced both growth and phenol degradation by the two selected Streptomyces isolate. Degradation process by isolate BA4 could be a promising solution for removal of phenol from wastewater.


Foods ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 300 ◽  
Author(s):  
Tsakona ◽  
Papadaki ◽  
Kopsahelis ◽  
Kachrimanidou ◽  
Papanikolaou ◽  
...  

Diversified mixed confectionery waste streams were utilized in a two-stage bioprocess to formulate a nutrient-rich fermentation media for microbial oil production. Solid-state fermentation was conducted for the production of crude enzyme consortia to be subsequently applied in hydrolytic reactions to break down starch, disaccharides, and proteins into monosaccharides, amino acids, and peptides. Crude hydrolysates were evaluated in bioconversion processes using the red yeast Rhodosporidium toruloides DSM 4444 both in batch and fed-batch mode. Under nitrogen-limiting conditions, during fed-batch cultures, the concentration of microbial lipids reached 16.6–17 g·L−1 with the intracellular content being more than 40% (w/w) in both hydrolysates applied. R. toruloides was able to metabolize mixed carbon sources without catabolite repression. The fatty acid profile of the produced lipids was altered based on the substrate employed in the bioconversion process. Microbial lipids were rich in polyunsaturated fatty acids, with oleic acid being the major fatty acid (61.7%, w/w). This study showed that mixed food side-streams could be valorized for the production of microbial oil with high unsaturation degree, pointing towards the potential to produce tailor-made lipids for specific food applications. Likewise, the proposed process conforms unequivocally to the principles of the circular economy, as the entire quantity of confectionery by-products are implemented to generate added-value compounds that will find applications in the same original industry, thus closing the loop.


Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 530 ◽  
Author(s):  
Bao-Teng Wang ◽  
Shuang Hu ◽  
Xing-Ye Yu ◽  
Long Jin ◽  
Yun-Jia Zhu ◽  
...  

Polysaccharides are biopolymers made up of a large number of monosaccharides joined together by glycosidic bonds. Polysaccharides are widely distributed in nature: Some, such as peptidoglycan and cellulose, are the components that make up the cell walls of bacteria and plants, and some, such as starch and glycogen, are used as carbohydrate storage in plants and animals. Fungi exist in a variety of natural environments and can exploit a wide range of carbon sources. They play a crucial role in the global carbon cycle because of their ability to break down plant biomass, which is composed primarily of cell wall polysaccharides, including cellulose, hemicellulose, and pectin. Fungi produce a variety of enzymes that in combination degrade cell wall polysaccharides into different monosaccharides. Starch, the main component of grain, is also a polysaccharide that can be broken down into monosaccharides by fungi. These monosaccharides can be used for energy or as precursors for the biosynthesis of biomolecules through a series of enzymatic reactions. Industrial fermentation by microbes has been widely used to produce traditional foods, beverages, and biofuels from starch and to a lesser extent plant biomass. This review focuses on the degradation and utilization of plant homopolysaccharides, cellulose and starch; summarizes the activities of the enzymes involved and the regulation of the induction of the enzymes in well-studied filamentous fungi.


1991 ◽  
Vol 69 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Sharon Harney ◽  
Paul Widden

Fifty-four strains of the entomopathogenic fungus Paecilomyces farinosus, half of which had been isolated from balsam fir litter and half of which had been isolated from naturally infected spruce budworm larvae, were evaluated for their use of a number of complex carbohydrates and other carbon sources, to determine their potential saprophytic ability. The fungi were also tested for (i) their ability to grow on and to decompose balsam fir litter, and (ii) their ability to survive desiccation, which is likely to occur in the tree canopy. The fungi produced a wide range of enzymes, including cellulases, chitinases, and proteases. They also grew on and decomposed balsam fir litter. A discriminant analysis showed a tendency for the strains isolated from spruce budworm to grow better on gelatin, whereas those from the litter grew better on cellulose. We conclude that P. farinosus is a versatile saprophyte, capable of opportunistically parasitizing spruce budworm larvae. These characteristics could be important when considering P. farinosus as a possible agent of biological control. Key words: Paecilomyces farinosus, entomopathogen, spruce budworm, saprophytic ability, hydrolases.


2013 ◽  
Vol 63 (Pt_7) ◽  
pp. 2666-2671 ◽  
Author(s):  
Felizitas Bajerski ◽  
Lars Ganzert ◽  
Kai Mangelsdorf ◽  
Lisa Padur ◽  
André Lipski ◽  
...  

During diversity studies of the glacier forefields of the Larsemann Hills, East Antarctica, a novel psychrotolerant, non-motile Gram-negative, shiny yellow, rod-shaped, aerobic bacterium, designated strain PB4T was isolated from a soil sample. Strain PB4T produces indole from tryptophan and hydrolyses casein. It grows between 0 and 25 °C with an optimum growth temperature of 20 °C. A wide range of substrates are used as sole carbon sources and acid is produced from numerous carbohydrates. The major menaquinone is MK-6. Identified polar lipids are ethanolamines and ornithine lipids. Major fatty acids (>10 %) are iso-C15 : 0 (13.0 %) and iso-2OH-C15 : 0 (51.2 %). G+C content is 33.7 mol%. The polyamine pattern is composed of sym-homospermidine (25.1 µmol g−1 dry weight), minor amounts of cadaverine (0.2 µmol g−1 dry weight) and spermidine (0.4 µmol g−1 dry weight) and traces of putrescine and spermine (<0.1 µmol g−1 dry weight). Strain PB4T had highest 16S rRNA gene similarities with the type strains of Chryseobacterium humi (97.0 %) and Chryseobacterium marinum (96.5 %). Considering phenotypic and genotypic characterization, strain PB4T represents a novel species in the genus Chryseobacterium (family Flavobacteriaceae ), for which the name Chryseobacterium frigidisoli sp. nov. is proposed. The type strain is PB4T ( = DSM 26000T = LMG 27025T).


Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 795 ◽  
Author(s):  
Helberth Júnnior Santos Lopes ◽  
Nemailla Bonturi ◽  
Everson Alves Miranda

Microbial oil is a potential substitute for vegetable oils in the biodiesel industry. Efforts to obtain cheap carbon sources for the cultivation of lipid-producing microorganisms comprise an active research area. This work aimed to extract the hemicellulose fraction from Eucalyptus uograndis and to use its hydrolysate as a carbon source for Rhodotorula toruloides (an oleaginous yeast) cultivation for microbial oil production. Hemicellulose hydrothermal extractions were performed at different temperatures, times, and ratios of solid to liquid (S/L). Temperature and time showed a stronger effect on the solubilization of hemicellulose. Hemicellulose extraction at 155 °C, 195 min, and an S/L ratio of 1/2 resulted in a hydrolysate with a xylose content of 37.0 g/l. R. toruloides cultivation in this hydrolysate showed that initial pH had a strong influence on cell growth. At an initial pH of 6.2, cells grew to 6.0 g/l of biomass with a lipid content of 50%. Therefore, we believe that E. urograndis hemicellulose hydrolysate could be a potential substrate for R. toruloides for lipid production based on the biorefinery concept.


Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 68
Author(s):  
Agata Fabiszewska ◽  
Katarzyna Wierzchowska ◽  
Agnieszka Górska ◽  
Bartłomiej Zieniuk

Microbial oils, also called single-cell oils, are lipids synthesized by microorganisms exceeding 20% of the dry weight of the cell. The aim of this work was to investigate the possibility of applying a rapeseed post-frying oil from fish fillets as a carbon source in growth medium for Yarrowia lipolytica oleaginous yeast species in order to synthesize a microbial oil. The key contribution of this work is that the solution provides a sustainable method for valorization of post-frying waste oil. Shaken batch cultures were provided and the influence of triacylglyceride hydrolysis on yeast growth was evaluated. In conclusion, post-frying rapeseed oil seems to be an easily utilizable carbon source by yeast. Regardless of the method of lipid substrate pretreatment, the yeast strain preferentially accumulated oleic acid (C18: 1) from 52.07% to 66.62% and linoleic acid (C18: 2) from 12.98% to 24.10%. To the best of our knowledge, this is the first report of using the oxygen nanobubbles as an unconventional method of aerating the culture medium containing lipid carbon sources. The use of water oxygenated with nano-sized bubbles to prepare culture media resulted in obtaining a higher yield of biomass compared to the biomass yield in distilled water-based medium.


Author(s):  
Gehan F. Galal ◽  
Rania F. Ahmed

Some agro-industrial wastes such as clarified cane molasses, high test molasses, sweet whey, potato starch and corn steep liquor were tested as carbon sources or nitrogen source for growth and carotenoid accumulation using bacteria Erwinia uredovora DSMZ 30080 and yeast Rhodotorula glutinis number 32. Erlenmeyer flasks containing 100 ml of production media, the flasks were inoculated with 1 ml of standard inoculum and incubated at 150 rpm for 4 days at 30°C. Samples were collected periodical every 24h, cell dry weight and carotenoids concentration were determined. Sweet whey and highest molasses gave the highest growth being 2.85 and 7.34 gl-1, respectively and scored the same layout on carotenoids conc. which reach the peak during stationary phase (72 h of fermentation). Using of high test molasses and sweet whey as carotenoid production media were incremented carotenoid conc. about 1.7 and 2 fold (with respect to reference media). Increasing high test molasses conc. to give 5% initial sugar led to up great growth, carotenoids conc., productivity, yield and Yc/x from Rhodo. glutinis 32 to be 7.31 gl-1, 2.67 mgl-1, 0.037 mgl-1h-1, 0.067% and 0.365, respectively. Furthermore, using corn steep liquor (30%) as nitrogen sources augmented carotenoids concentration about 3.8 and 4fold for incomplete and complete production media using Rhodo. glutinis32. Also, a negligible effect on growth was observed with dark incubation with both strains which dropped about 75 and 48% with regard to control for E. uredovora DSMZ 30080 and Rhod. glutinis 32, respectively, whereas, carotenoids conc. was increased about 21% for E. uredovora DSMZ 30080 in dark condition.


2020 ◽  
Vol 64 (10) ◽  
Author(s):  
Olga Pacios ◽  
Lucia Blasco ◽  
Inés Bleriot ◽  
Laura Fernandez-Garcia ◽  
Antón Ambroa ◽  
...  

ABSTRACT Antibiotic failure not only is due to the development of resistance by pathogens but can also often be explained by persistence and tolerance. Persistence and tolerance can be included in the “persistent phenotype,” with high relevance for clinics. Two of the most important molecular mechanisms involved in tolerance and persistence are toxin-antitoxin (TA) modules and signaling via guanosine pentaphosphate/tetraphosphate [(p)ppGpp], also known as “magic spot.” (p)ppGpp is a very important stress alarmone which orchestrates the stringent response in bacteria; hence, (p)ppGpp is produced during amino acid or fatty acid starvation by proteins belonging to the RelA/SpoT homolog family (RSH). However, (p)ppGpp levels can also accumulate in response to a wide range of signals, including oxygen variation, pH downshift, osmotic shock, temperature shift, or even exposure to darkness. Furthermore, the stringent response is not only involved in responses to environmental stresses (starvation for carbon sources, fatty acids, and phosphates or heat shock), but it is also used in bacterial pathogenesis, host invasion, and antibiotic tolerance and persistence. Given the exhaustive and contradictory literature surrounding the role of (p)ppGpp in bacterial persistence, and with the aim of summarizing what is known so far about the magic spot in this bacterial stage, this review provides new insights into the link between the stringent response and persistence. Moreover, we review some of the innovative treatments that have (p)ppGpp as a target, which are in the spotlight of the scientific community as candidates for effective antipersistence agents.


2016 ◽  
Vol 851 ◽  
pp. 20-25 ◽  
Author(s):  
Stanislav Obruca ◽  
Leos Doskocil ◽  
Vladislav Krzyzanek ◽  
Kamila Hrubanova ◽  
Petr Sedlacek ◽  
...  

Since polyhydroxyalkanoates (PHAs) belong among the most widespread storage materials within bacteria genus, it can be assumed that the ability of PHAs accumulation represent significant advantage in the natural environments. Of course, probably the most obvious is the possibility to utilize PHAs when external carbon sources are depleted. Nevertheless, it is likely that PHAs play much more complex role in the stress response of bacteria. Therefore, the aim of this work was to investigate possible influence of PHA accumulation in bacteria on physical properties of the cells and their cytoplasm with respect to possible stress survival. Cells of bacteria Cupriavidus necator H16 with various poly(3-hydroxybutyrate) (PHB) content (25 – 91 % of cell dry weight) were subjected to analytical centrifugation employing LUMiSizer. We observed that slope of index instability of bacterial culture increased with rise of PHB content in cells. It indicates that accumulation of PHB granules in bacterial cells affects overall physico-mechanical properties of the cells in particular sedimentation potential and density which might influence their behavior in natural environment such as sedimentation, surface absorption and subsequent biofilm formation. Furthermore, when investigated by Cryo-SEM, the PHB containing cells showed needle-type plastic deformations while these structures were absent in the cells without polymer. This suggests that native intracellular PHB granules reveal completely different mechanical and physico-chemical properties than any other component of bacterial cytoplasm and their flexibility even in deeply-frozen state is significantly higher than that of PHB isolated from bacterial cells. Based on these observations, it can be expected that, aside from their involvement in metabolism, presence of PHB granules dramatically changes physico-mechanical properties of cytoplasm and overall properties of cells which might represent important advantage when cells are exposed to stress conditions.


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