alternative carbon source
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2023 ◽  
Vol 83 ◽  
Author(s):  
B. Kalim ◽  
N. M. Ali ◽  
A. Iqbal ◽  
M. T. Zahid ◽  
S. Rehman ◽  
...  

Abstract In recent days, cheapest alternative carbon source for fermentation purpose is desirable to minimize production cost. Xylanases have become attractive enzymes as their potential in bio-bleaching of pulp and paper industry. The objective of the present study was to identify the potential ability on the xylanase production by locally isolated Bacillus pumilus BS131 by using waste fiber sludge and wheat bran media under submerged fermentation. Culture growth conditions were optimized to obtain significant amount of xylanase. Maximum xylanase production was recorded after 72 hours of incubation at 30 °C and 7 pH with 4.0% substrate concentration. In the nutshell, the production of xylanase using inexpensive waste fiber sludge and wheat-bran as an alternative in place of expensive xylan substrate was more cost effective and environment friendly.


Author(s):  
Zhishuai Chang ◽  
Wei Dai ◽  
Yufeng Mao ◽  
Zhenzhen Cui ◽  
Zhidan Zhang ◽  
...  

Acetate is an economical and environmental-friendly alternative carbon source. Herein, the potential of harnessing Corynebacterium glutamicum as a host to produce 3-hydroxypropionic acid (3-HP) from acetate was explored. First, the expression level of malonyl-CoA reductase from Chloroflexus aurantiacus was optimized through several strategies, strain Cgz2/sod-N-C* showed an MCR enzyme activity of 63 nmol/mg/min and a 3-HP titer of 0.66 g/L in flasks. Next, the expression of citrate synthase in Cgz2/sod-N-C* was weakened to reduce the acetyl-CoA consumption in the TCA cycle, and the resulting strain Cgz12/sod-N-C* produced 2.39 g/L 3-HP from 9.32 g/L acetate. However, the subsequent deregulation of the expression of acetyl-CoA carboxylase genes in Cgz12/sod-N-C* resulted in an increased accumulation of intracellular fatty acids, instead of 3-HP. Accordingly, cerulenin was used to inhibit fatty acid synthesis in Cgz14/sod-N-C*, and its 3-HP titer was further increased to 4.26 g/L, with a yield of 0.50 g 3-HP/g-acetate. Finally, the engineered strain accumulated 17.1 g/L 3-HP in a bioreactor without cerulenin addition, representing the highest titer achieved using acetate as substrate. The results demonstrated that Corynebacterium glutamicum is a promising host for 3-HP production from acetate.


2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Prasansah Shrestha ◽  
Min-Su Kim ◽  
Ermal Elbasani ◽  
Jeong-Dong Kim ◽  
Tae-Jin Oh

Abstract Background Metabolism including anabolism and catabolism is a prerequisite phenomenon for all living organisms. Anabolism refers to the synthesis of the entire compound needed by a species. Catabolism refers to the breakdown of molecules to obtain energy. Many metabolic pathways are undisclosed and many organism-specific enzymes involved in metabolism are misplaced. When predicting a specific metabolic pathway of a microorganism, the first and foremost steps is to explore available online databases. Among many online databases, KEGG and MetaCyc pathway databases were used to deduce trehalose metabolic network for bacteria Variovorax sp. PAMC28711. Trehalose, a disaccharide, is used by the microorganism as an alternative carbon source. Results While using KEGG and MetaCyc databases, we found that the KEGG pathway database had one missing enzyme (maltooligosyl-trehalose synthase, EC 5.4.99.15). The MetaCyc pathway database also had some enzymes. However, when we used RAST to annotate the entire genome of Variovorax sp. PAMC28711, we found that all enzymes that were missing in KEGG and MetaCyc databases were involved in the trehalose metabolic pathway. Conclusions Findings of this study shed light on bioinformatics tools and raise awareness among researchers about the importance of conducting detailed investigation before proceeding with any further work. While such comparison for databases such as KEGG and MetaCyc has been done before, it has never been done with a specific microbial pathway. Such studies are useful for future improvement of bioinformatics tools to reduce limitations.


Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 977
Author(s):  
Maria Cristina Collivignarelli ◽  
Alessandro Abbà ◽  
Francesca Maria Caccamo ◽  
Marco Carnevale Miino ◽  
Angela Durante ◽  
...  

Minimizing the biological sewage sludge (BSS) produced by wastewater treatment plants (WWTPs) represents an increasingly difficult challenge. With this goal, tests on a semi-full scale Thermophilic Alternate Membrane Biological Reactor (ThAlMBR) were carried out for 12 months. ThAlMBR was applied both on thickened (TBSS) and digested biological sewage sludge (DBSS) with alternating aeration conditions, and emerged: (i) high COD removal yields (up to 90%), (ii) a low specific sludge production (0.02–0.05 kgVS produced/kgCODremoved), (iii) the possibility of recovery the aqueous carbon residue (permeate) in denitrification processes, replacing purchased external carbon sources. Based on the respirometric tests, an excellent biological treatability of the permeate by the mesophilic biomass was observed and the denitrification kinetics reached with the diluted permeate ((4.0 mgN-NO3−/(gVSS h)) were found comparable to those of methanol (4.4 mgN-NO3−/(gVSS h)). Moreover, thanks to the similar results obtained on TBSS and DBSS, ThAlMBR proved to be compatible with diverse sludge line points, ensuring in both cases an important sludge minimization.


PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0260032
Author(s):  
Irina B. Ivshina ◽  
Elena A. Tyumina ◽  
Grigory A. Bazhutin ◽  
Elena V. Vikhareva

The article expands our knowledge on the variety of biodegraders of ibuprofen, one of the most frequently detected non-steroidal anti-inflammatory drugs in the environment. We studied the dynamics of ibuprofen decomposition and its relationship with the physiological status of bacteria and with additional carbon and energy sources. The involvement of cytoplasmic enzymes in ibuprofen biodegradation was confirmed. Within the tested actinobacteria, Rhodococcus cerastii IEGM 1278 was capable of complete oxidation of 100 μg/L and 100 mg/L of ibuprofen in 30 h and 144 h, respectively, in the presence of an alternative carbon source (n-hexadecane). Besides, the presence of ibuprofen induced a transition of rhodococci from single- to multicellular lifeforms, a shift to more negative zeta potential values, and a decrease in the membrane permeability. The initial steps of ibuprofen biotransformation by R. cerastii IEGM 1278 involved the formation of hydroxylated and decarboxylated derivatives with higher phytotoxicity than the parent compound (ibuprofen). The data obtained indicate potential threats of this pharmaceutical pollutant and its metabolites to biota and natural ecosystems.


2021 ◽  
pp. 126312
Author(s):  
Yaning Xu ◽  
Xuemei Wang ◽  
Zifu Li ◽  
Shikun Cheng ◽  
Jiacheng Jiang

2021 ◽  
Vol 89 (2) ◽  
Author(s):  
Diah - RATNANINGRUM ◽  
Een Sri ENDAH ◽  
Puspita LISDIYANTI ◽  
Sri PRIATNI ◽  
Vienna SARASWATY

Burkholderia sp. has been reported as a poly-hydroxy-butyrate (PHB) producer. PHB is a natural polyester class with a wide range of applications in foods, medicines, and biomedicines. However, the high production cost of PHB may limit its potential. Molasses, a by-product of the sugarcane industry available abundantly, may be used as an alternative carbon source of PHB production. In this research, we aimed to evaluate PHB production by Burkholderia sp. B73 in fermentation media using molasses as an alternative carbon source. Small-scale experiments were performed in Erlenmeyer flasks on a shaker at 150 rpm and 30 °C to evaluate the best initial C/N ratio for biomass accumulation and PHB production. A set of parameters including bacterial growth, dry cell weight, yield, and FTIR spectrum of PHB were observed.  The results showed that molasses could be used to grow Burkholderia sp. B73 and the highest PHB production was obtained when a 20:1 C/N ratio of molasses was applied in the fermentation medium. In addition, when the initial pH was adjusted to 7.0, the highest PHB yield was also produced. More importantly, the use of molasses as a carbon source improved the PHB yield by nearly 2-fold compared with our previous report using a synthetic Ramsay’s minimal medium. In conclusion, the experiment results showed that molasses could be used as a low-cost carbon source for PHB production by Burkholderia sp. B73 bacteria.


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