To find whether productivity of bacteriocin is controlled between different species under unusual cultural conditions, we used Rhodobacter capsulatus ATCC 17016 as a producer and Rhodopseudomonas palustris ATCC 17003 as an indicator. Rhodobacter capsulatus was cultured under aerobic conditions in the dark in Lascelles medium containing 0.3% Triton X-100. As a result, bacteriocin productivity increased enormously. The optimal pH range of bacteriocin production was 6~7.8. Through partial purification of bacteriocin, the molecular weight was roughly estimated at 14 kDa. Plasmid had no influence on bacteriocin production by Rhodobacter capsulatus. Our findings indicate that culture conditions affect bacteriocin productivity between more distantly related species, and bacteriocin of Rhodobacter capsulatus is not encoded by a plasmid.
Bacteria ; Efficiency ; Hydrogen-Ion Concentration ; Molecular Weight ; Octoxynol ; Plasmids ; Rhodobacter ; Rhodobacter capsulatus ; Rhodopseudomonas

5-Aminolevulinic acid is the key intermediate of the tetrapyrrole biosynthesis pathway in organisms and has broad application potentials. This review summarized and discussed recent progress in microbial production of 5-aminolevulinic acid, including screening, isolation and mutation of microbes to produce 5-aminolevulinic acid; microbial whole-cell transformation to synthesize 5-aminolevulinic acid depending on the C4 pathway; construction of high-yield 5-aminolevulinic acid producing strains by metabolic engineering. Finally, future research directions in microbial production of 5-aminolevulinic acid were addressed.
Aminolevulinic Acid ; metabolism ; Escherichia coli ; genetics ; metabolism ; Metabolic Engineering ; Mutation ; Rhodobacter sphaeroides ; genetics ; metabolism

5-aminolevulinic acid (5-ALA) plays an important role in the fields of medicine and agriculture. 5-ALA can be produced by engineered Escherichia coli and Corynebacterium glutamicum. We systematically engineered the C4 metabolic pathway of C. glutamicum to further improve its ability to produce 5-ALA. Firstly, the hemA gene encoding 5-ALA synthase (ALAS) from Rhodobacter capsulatus and Rhodopseudomonas palustris were heterologously expressed in C. glutamicum, respectively. The RphemA gene of R. palustris which showed relatively high enzyme activity was selected. Screening of the optimal ribosome binding site sequence RBS5 significantly increased the activity of RphemA. The ALAS activity of the recombinant strain reached (221.87±3.10) U/mg and 5-ALA production increased by 14.3%. Subsequently, knocking out genes encoding α-ketoglutarate dehydrogenase inhibitor protein (odhI) and succinate dehydrogenase (sdhA) increased the flux of succinyl CoA towards the production of 5-ALA. Moreover, inhibiting the expression of hemB by means of sRNA reduced the degradation of 5-ALA, while overexpressing the cysteine/O-acetylserine transporter eamA increased the output efficiency of intracellular 5-ALA. Shake flask fermentation using the engineered strain C. glutamicum 13032/∆odhI/∆sdhA-sRNAhemB- RBS5RphemA-eamA resulted in a yield of 11.90 g/L, which was 57% higher than that of the original strain. Fed-batch fermentation using the engineered strain in a 5 L fermenter produced 25.05 g/L of 5-ALA within 48 h, which is the highest reported-to-date yield of 5-ALA from glucose.
Aminolevulinic Acid/metabolism* ; Corynebacterium glutamicum/metabolism* ; Fermentation ; Metabolic Engineering ; Rhodobacter capsulatus/enzymology* ; Rhodopseudomonas/enzymology*

The objectives of this study were to assess the potential of two photosynthetic bacteria (PSB), Rhodopseudomonas palustris HZ0301 and Rhodobacter sphaeroides HZ0302, as probiotics in aquaculture. The viability of HZ0301 and HZ0302 in simulated gastric transit conditions (pH 2.0, pH 3.0 and pH 4.0 gastric juices) and in simulated small intestinal transit conditions (pH 8.0, with or without 0.3% bile salts) was tested. The effects of HZ0301 and HZ0302 on the viability and permeability of intestinal epithelial cell in primary culture of tilapias, Oreochromis nilotica, were also detected. All the treatments were determined with three replicates. The simulated gastric transit tolerance of HZ0301 and HZ0302 strains was pH-dependent and correspondingly showed lower viability at pH 2.0 after 180 min compared with pH 3.0 and pH 4.0. Both HZ0301 and HZ0302 were tolerant to simulated small intestine transit with or without bile salts in our research. Moreover, there was no significant difference (P>0.05) among three treatments including the control and the groups treated with HZ0301 or HZ0302 both in intestinal epithelial cell viability and membrane permeability, showing no cell damage. In summary, this study demonstrated that HZ0301 and HZ0302 had high capacity of upper gastrointestinal transit tolerance and were relatively safe for intestinal epithelial cells of tilapias.
Animals ; Gastrointestinal Tract ; microbiology ; Microbial Viability ; Phototrophic Processes ; Rhodobacter sphaeroides ; isolation & purification ; physiology ; Rhodopseudomonas ; isolation & purification ; physiology ; Species Specificity ; Tilapia ; microbiology

Coenzyme Q10 (CoQ10) is a lipophilic antioxidant that improves human immunity, delays senility and enhances the vitality of the human body and has wide applications in pharmaceutical and cosmetic industries. Microbial fermentation is a sustainable way to produce CoQ10, and attracts increased interest. In this work, the native CoQ8 synthetic pathway of Escherichia coli was replaced by the CoQ10 synthetic pathway through integrating decaprenyl diphosphate synthase gene (dps) from Rhodobacter sphaeroides into chromosome of E. coli ATCC 8739, followed by deletion of the native octaprenyl diphosphate synthase gene (ispB). The resulting strain GD-14 produced 0.68 mg/L CoQ10 with a yield of 0.54 mg/g DCW. Modulation of dxs and idi genes of the MEP pathway and ubiCA genes in combination led to 2.46-fold increase of CoQ10 production (from 0.54 to 1.87 mg/g DCW). Recruiting glucose facilitator protein of Zymomonas mobilis to replace the native phosphoenolpyruvate: carbohydrate phosphotransferase systems (PTS) further led to a 16% increase of CoQ10 yield. Finally, fed-batch fermentation of the best strain GD-51 was performed, which produced 433 mg/L CoQ10 with a yield of 11.7 mg/g DCW. To the best of our knowledge, this was the highest CoQ10 titer and yield obtained for engineered E. coli.
Alkyl and Aryl Transferases ; genetics ; Bacterial Proteins ; genetics ; Batch Cell Culture Techniques ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Gene Deletion ; Industrial Microbiology ; Metabolic Engineering ; Rhodobacter sphaeroides ; enzymology ; genetics ; Ubiquinone ; analogs & derivatives ; biosynthesis ; Zymomonas ; genetics