Chapter 13 Applications of mixed microbial cultures in industrial biotechnology

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.

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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

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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.

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