Clove Oil (Syzygium aromaticum L.) Activity against Alicyclobacillus acidoterrestris Biofilm on Technical Surfaces

Acidotermophilic bacteria Alicyclobacillus acidoterrestris is one of the main contaminants in the fruit industry forming biofilms which are difficult to remove from the production line by conventional methods. An alternative approach aims for the use of essential oils to prevent Alicyclobacillus biofilm development. The effect of clove essential oil on A. acidoterrestris biofilms on glass and polyvinyl chloride surfaces under static and agitated culture conditions was investigated by atomic force microscopy and the plate count method. The medium-flow and the type of technical surface significantly influenced A. acidoterrestris biofilm. The PVC was colonized in a greater extent comparing to glass. Clove essential oil in 0.05% (v/v) caused 25.1–65.0% reduction of biofilms on the technical surfaces along with substantial changes in their morphology by a decrease in the biofilm: height, surface roughness, and surface area difference. The oil also induced alteration in individual bacterial cells length and visible increase of their roughness. Clove essential oil seems to release EPS from biofilm and thus induce detachment of bacteria from the surface. Due to anti-A. acidoterrestris biofilm activity, the clove oil may be used in the juice industry to hinder a development of A. acidoterrestris biofilms on production surfaces.

Production and Characterization of Bacterial Cellulose from Rice Washing Drainage (RWD) by Komagataeibacter nataicola Li1

Bacterial cellulose (BC), produced by some bacteria has received attention because its high purity and robust characteristics enable its use in medicine and industry. This study aimed to screen bacteria capable of producing BC from fruits, and to optimize the BC production in both traditional YE yeast fermentation and Schramm and Hestrin (SH) media. The rice washing drainage without any pretreatment as the sole carbon source in the yeast medium was also investigated for BC production in both static and agitated cultures. The bacterial strain Li1 isolated from apple (Malus pumila) was identified as Komagataeibacter (Gluconacetobacter) nataicola based on 16S rDNA sequence analysis. K. nataicola Li1 cultured in a YE medium produced significantly more BC than that in a SH medium in the static culture. Moreover, the weight yields of dry BC films obtained from rice washing drainage and YE media in the static cultures were not significantly different. However, in the agitated culture, the weight yields of dry BC films were more significant in the YE medium than in rice washing drainage medium. In addition, the structure and properties of BC were determined using SEM, FTIR, DSC and XRD. This study shows that rice washing drainage can be used as the carbon source for BC production by K. nataicola Li1.

A Mini-Review on the Progress of Spherical Bacterial Cellulose Production

Bacterial cellulose (BC) is a polymer produced by some bacteria and it is highly pure when compared to plant cellulose. Its structure and properties are unique, which makes it a material of a large commercial interest due to its broad potential of applications. The biosynthesis of BC may be carried out in two ways either static or agitated culture. Static culture usually generates BC membranes whereas agitated tends to produce spherical shapes. The production in agitated culture often enables an increase of yield for cellulose production. However, it provides a material with lower mechanical properties compared to static culture. The processing parameters and the phenomena governing the formation of BC in agitated cultivation have not fully established. A greater understanding of the phenomena and parameters inherent in the production of BC in agitated culture is necessary to achieve a technological progress. Some limitations concerning molecular weight control and BC structure made in agitated culture can improve with a better understanding of the culture conditions and the biosynthesis evolution. The ex-situ or in-situ insertion of additives may be performed to increase some specific properties of BC over agitated culture. Thus, the principal objective of this work is to discuss and provide a broad literature review on the techniques of BC production by agitated culture.