Carbon Source Applied in Enrichment Stage of Mixed Microbial Cultures Limits the Substrate Adaptability for PHA Fermentation Using the Renewable Carbon

Production of polyhydroxyalkanoates (PHA) has generated great interest as building blocks for bioplastic production. Their production using mixed microbial cultures represents an interesting alternative, since it enables the use of organic wastes as a carbon source. Feast/famine strategy is a common way to promote selection of microorganisms with PHA accumulation capacity. However, when using waste sources, changes in substrate concentration are expected, that may affect performance and efficiency of the process. This study showed how the dissolved oxygen level can be used for online control of the cycle time, ensuring that the desired feast/famine ratio is effectively applied. An operation strategy is presented and validated, using sequential batch reactors fed with acetate as the carbon source. Production of polyhydroxybutyrate (PHB) was studied, which is the expected type of PHA to be synthetized when using acetate as substrate. Two reactors were operated by applying the proposed control strategy, to provide F/F ratios of 0.2 and 0.6, respectively. A third reactor was operated with a fixed cycle time, for comparison purposes. Results showed that the reactor that operated at an F/F ratio of 0.6 promoted higher biomass productivity and PHB content, as a result of a better use of available time, preventing unnecessary long famine times. The application of the tested strategy is a simple a reliable way to promote a better performance of feast/famine-based bioreactors involving mixed microbial cultures for PHB production.

Download Full-text

Beyond PHA: Stimulating intracellular accumulation of added-value compounds in mixed microbial cultures

Bioresource Technology ◽

10.1016/j.biortech.2021.125381 ◽

2021 ◽

pp. 125381

Author(s):

F. Pinto-Ibieta ◽

A. Serrano ◽

M. Cea ◽

G. Ciudad ◽

F.G. Fermoso

Keyword(s):

Added Value ◽

Intracellular Accumulation ◽

Microbial Cultures ◽

Mixed Microbial Cultures

Download Full-text

Assessment of Long-Term Fermentability of PHA-Based Materials from Pure and Mixed Microbial Cultures for Potential Environmental Applications

Water ◽

10.3390/w13070897 ◽

2021 ◽

Vol 13 (7) ◽

pp. 897

Author(s):

Neda Amanat ◽

Bruna Matturro ◽

Marta Maria Rossi ◽

Francesco Valentino ◽

Marianna Villano ◽

...

Keyword(s):

Environmental Remediation ◽

Volatile Fatty Acids ◽

Rapid Onset ◽

Pilot Scale ◽

Point Of View ◽

Microbial Cultures ◽

Extraction And Purification ◽

Fermentation Pattern ◽

Mixed Microbial Cultures

The use of polyhydroxyalkanoates (PHA) as slow-release electron donors for environmental remediation represents a novel and appealing application that is attracting considerable attention in the scientific community. In this context, here, the fermentation pattern of different types of PHA-based materials has been investigated in batch and continuous-flow experiments. Along with commercially available materials, produced from axenic microbial cultures, PHA produced at pilot scale by mixed microbial cultures (MMC) using waste feedstock have been also tested. As a main finding, a rapid onset of volatile fatty acids (VFA) production was observed with a low-purity MMC-deriving material, consisting of microbial cells containing 56% (on weight basis) of intracellular PHA. Indeed, with this material a sustained, long-term production of organic acids (i.e., acetic, propionic, and butyric acids) was observed. In addition, the obtained yield of conversion into acids (up to 70% gVFA/gPHA) was higher than that obtained with the other tested materials, made of extracted and purified PHA. These results clearly suggest the possibility to directly use the PHA-rich cells deriving from the MMC production process, with no need of extraction and purification procedures, as a sustainable and effective carbon source bringing remarkable advantages from an economic and environmental point of view.

Download Full-text

Insights into enhanced polyhydroxyalkanoate production by the synergistic use of waste wood hydrolysate and volatile fatty acids by mixed microbial cultures

Bioresource Technology ◽

10.1016/j.biortech.2021.125488 ◽

2021 ◽

pp. 125488

Author(s):

Dongna Li ◽

Xiaojun Ma ◽

Jianing Li ◽

Binqing Sun

Keyword(s):

Fatty Acids ◽

Volatile Fatty Acids ◽

Waste Wood ◽

Microbial Cultures ◽

Mixed Microbial Cultures ◽

Wood Hydrolysate

Download Full-text

Use of Bioproducts Derived from Mixed Microbial Cultures Grown with Crude Glycerol to Protect Recycled Concrete Surfaces

Materials ◽

10.3390/ma14082057 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2057

Author(s):

Lorena Serrano-González ◽

Daniel Merino-Maldonado ◽

Manuel Ignacio Guerra-Romero ◽

Julia María Morán-del Pozo ◽

Paulo Costa Lemos ◽

...

Keyword(s):

Water Absorption ◽

Crude Glycerol ◽

Protective Layer ◽

Recycled Concrete ◽

Recycled Aggregate ◽

World Population ◽

Management Problem ◽

Waste Glycerol ◽

Microbial Cultures ◽

Mixed Microbial Cultures

The large increase in the world population has resulted in a very large amount of construction waste, as well as a large amount of waste glycerol from transesterification reactions of acyl glycerides from oils and fats, in particular from the production of biodiesel. Only a limited percentage of these two residues are recycled, which generates a large management problem worldwide. For that reason, in this study, we used crude glycerol as a carbon source to cultivate polyhydroxyalkanoates (PHA)-producing mixed microbial cultures (MMC). Two bioproducts derived from these cultures were applied on the surface of concrete with recycled aggregate to create a protective layer. To evaluate the effect of the treatments, tests of water absorption by capillarity and under low pressure with Karsten tubes were performed. Furthermore, SEM-EDS analysis showed the physical barrier caused by biotreatments that produced a reduction on capillarity water absorption of up to 20% and improved the impermeability of recycled concrete against the penetration of water under pressure up to 2.7 times relative to the reference. Therefore, this bioproduct shown to be a promising treatment to protect against penetration of water to concrete surfaces increasing its durability and useful life.

Download Full-text