Acetylated sophorolipid (SL) esters exhibit surface-active as well as bioactive properties. Their synthesis requires a three-step route comprising microbial production of the SL lactone followed by chemical transesterification and enzymatic re-acetylation. Here, a direct microbial synthesis of SL esters was investigated using three-component feeding of glucose, oleic acid and a wide variety of alcohols. Straight-chain primary alcohols with chain lengths of C3–C12 impaired SL production of Starmerella bombicola severely, whereas toxicity of short-chain primary, secondary and branched-chain alcohols was significantly lower, and total SL production of up to 60 g l−1 was obtained in initial shake-flask cultures. Besides lactonic, acidic and bolaform SLs, acetylated SL esters were detected in small quantities in the fermentation broth. Upon continuous alcohol feeding the SL ester fraction could be increased to 10–40 g l−1 of methyl, ethyl, isopropyl and isobutyl SL esters under optimized conditions. Following chromatographic purification, the ester structures were verified by LC–MS and NMR spectroscopy. The synthesis of the isopropyl SL ester was scaled up successfully to a 2 l bioreactor, yielding 100 g l−1 total SL including 30 g l−1 of the isopropyl ester. To elucidate the SL ester formation capabilities within the Starmerella clade, five additional species were screened. SL synthesis was shown for the first time with S. caucasica and S. davenportii. With all strains, including ω-hydroxylating open-chain SL producing S. kuoi and S. batistae, SL ester formation was detected. Thus, the ability for SL ester synthesis seems to be ubiquitous among SL producing Starmerella strains.
Virus-like particles (VLPs) have good potential for novel vaccine development. Particularly, HIV-1 Gag VLPs, present a robust platform for vaccine production. However, successful translation from the laboratory to biomanufacturing requires focus on formulation, with lyophilization playing a pivotal role in enhancing stability and facilitating distribution. The challenge lies in the potential damage inflicted during the lyophilization, impacting product integrity and stability. To address this, optimization of formulations and methodologies are imperative. Formulation excipients, play an important role, with cryo-lyo protectants, bulking agents, buffers, tonicity modifiers, and surfactants being commonly utilized. This work focuses on optimizing lyophilization formulation for Gag::eGFP VLPs, employing a Design of Experiments approach. The impact of five main excipients is studied, using size, concentration, and quality of the Gag::eGFP VLPs as attributes to characterize. Moreover, the impact of specific storage conditions after lyophilization is also evaluated. The lyophilized Gag::eGFP VLPs, formulated with the optimized formulation, exhibited characteristics akin to those observed in the non-lyophilized Gag::eGFP VLPs. The stability studies revealed the Gag::eGFP VLPs stored at 4 °C for 4 weeks, in lyophilized or reconstituted form maintain their integrity. While these results demonstrate short-term stability as a proof of concept, further studies are required to assess long-term shelf life. This work provides a systematic DoE-based framework for the optimization of lyophilized HIV-1 Gag VLP formulations and contributes new insights into the preservation of physicochemical quality attributes during freeze-drying and subsequent storage, supporting the future development of stable VLP-based vaccine platforms.
Captive conditions and shared diets may constrain gut microbial variation among host species, while residual differences may reflect species-associated patterns under the studied captive conditions. Sika deer (Cervus nippon) and fallow deer (Dama dama) are both cervids maintained under comparable zoo conditions, providing a useful model for examining whether microbiome differences persist when environmental variation is minimized. We characterized the fecal microbiota of 22 adult deer housed at Yinchuan City Zoo, including sika deer and fallow deer, using shotgun metagenomic sequencing. Firmicutes and Bacteroidetes dominated both groups, indicating a shared dominant phylum. Fallow deer exhibited higher Shannon diversity, whereas the other diversity indices showed no significant differences. Overall community structure showed substantial overlap between groups, with no significant separation detected by complementary statistical analyses. Nevertheless, specific bacterial and archaeal taxa differed between the two deer groups, and pathways related to allantoin, amino acid, glycosaminoglycan, and bioactive amine metabolism showed differential enrichment. Because several pathway differences were significant only before multiple-testing correction, they should be regarded as exploratory candidate functional signals requiring further validation. Overall, the two deer species shared a conserved fecal microbiome and basic functional framework, with between-group differences mainly involving specific microbial taxa and candidate metabolic pathways under the studied captive conditions.
The increasing cost of commercial culture media and the demand for sustainable bioprocesses have encouraged the use of agro-industrial by-products as alternative fermentation substrates. This study evaluated combined agro-dairy by-products for the growth of Lactiplantibacillus plantarum and postbiotic production. Rice bran and sugar beet pulp extracts were combined with whey powder and corn steep liquor (CSL) to formulate three waste-based media (WBM): WBM5, WBM8, and WBM11, containing the solid-derived components at 5, 8, and 11 g/L and CSL at 15, 20, and 25 mL/L, respectively. The formulations were compared with Base and de Man, Rogosa and Sharpe (MRS) media. Among the waste-based formulations, WBM8 showed the best overall performance, reaching an OD600 of 5.48 and 3.91 × 109 CFU/mL, compared with 6.36 and 8.10 × 109 CFU/mL in MRS. WBM8 produced 2.65 g/L lactic acid, 0.79 g/L acetic acid, 165.67 mg GAE/L total phenolic content, and 265 mg/L soluble protein. MRS showed higher lactic acid (3.11 g/L) and soluble protein (281.67 mg/L), while TPC was statistically comparable between MRS (168.67 mg GAE/L) and WBM8. WBM8 yielded a DPPH IC50 of 450 µg/mL and FRAP of 200 µmol Fe2+/g DW versus 478 µg/mL and 190 µmol Fe2+/g DW for MRS; these antioxidant indices did not differ significantly between WBM8 and MRS (p > 0.05). Approximately 87
The study aimed to investigate the upscaled culture-based production of the predatory bacterium, Bdellovibrio bacteriovorus (B. bacteriovorus) PF13 (isolated from wastewater) using metabolically active and heat-inactivated Escherichia coli (E. coli) ATCC 417373 as prey. This approach was used to assess whether heat-treated prey cells could support the production of predatory stock lysates. Heat-inactivation was validated using resazurin assays, which showed reduced relative fluorescence units (RFU) in all heat-treated, E. coli ATCC 417373 samples in comparison to the untreated controls, with the 65 °C treatment yielding the lowest RFU. The predatory lysate was then upscaled, using suspensions of either metabolically active or heat-inactivated (65 °C) E. coli ATCC 417373, from 100 mL to 1 L, and finally to 2.5 L. For the 100 mL, 1 L and 2.5 L co-cultures, using B. bacteriovorus PF13 and metabolically active E. coli ATCC 417373, the PFU/mL and cells/mL of B. bacteriovorus PF13 increased by 2.84 and 1.12 logs, 1.40 and 0.86 logs, and 2.37 and 0.80 logs, respectively. For the 100 mL, 1 L and 2.5 L co-cultures, using B. bacteriovorus PF13 and heat-inactivated E. coli ATCC 417373, the cells/mL of B. bacteriovorus PF13 then increased by 1.27 logs, 1.23 logs, and 0.29 logs, respectively. While further optimisation is required to produce predatory lysates in shorter incubation time periods, this study demonstrated the feasibility of upscaling B. bacteriovorus production using heat-inactivated prey and culture-based methods. This strategy may potentially circumvent the need for bioreactor infrastructure, which is particularly crucial for laboratories in resource-limited countries.
