Fermentation, Volume 2, Issue 4 (December 2016) – 4 articles

The sparkling wine market has expanded in recent years, boosted by the increasing demand of the global market. As for other fermented beverages, technological yeasts and bacteria selected to design commercial starter cultures represent key levers to maximize product quality and safety. The increasing economic interest in the sector of sparkling wine has also implied a renewed interest in microbial resource management. In this review, after a brief introduction, we report an overview of the main characterization criteria in order to select Saccharomyces cerevisiae strains suitable for use as starter cultures for the production of base wines and to drive re-fermentation of base wines to obtain sparkling wines. Particular attention has been reserved to the technological characterization aspects of re-fermenting phenotypes. We also analysed the possible uses of selected non-Saccharomyces and malolactic strains in order to differentiate specific productions. Finally, we highlighted the main safety aspects related to microbes of enological interest and underlined some microbial-based biotechnological applications helpful to pursue product and process innovations. Overall, the sparkling wine industry may find a relevant benefit from the exploitation of the wide resources associated with vineyard/wine microbial diversity. Full article

(1) Background: Probiotication is an important method in the food industry, and the use of probiotic dairy products has prevented lactose intolerant patients and vegetarians from their consumption. Hence, there is a need to incorporate probiotics in fruit juice without lactose; (2) Method: Probiotic viability, and physicochemical and sensory evaluation of stored probioticated pineapple juice using lactic acid bacteria (LAB) (Pediococcus pentosaceus LaG1, Lactobacillus rhamnosus GG, Pediococcus pentosaceus LBF2) as a single and mixed starter was investigated; (3) Results: There was an increase in the lactic acid production, and reduction in pH, vitamin C content, and colour during storage. At weeks 3 and 4, Propp2 and Pcontrol samples had the highest lactic acid content (317.9 mg/L and 160.34 mg/L). The vitamin C content ranged from 2.91–7.10 mg/100 g. There was a general reduction in total soluble solids during storage. The probiotic LAB were viable throughout the storage time (1.05–1.10 × 10⁹ cfu/mL) in the juice samples. There was no significant difference in terms of taste, aroma, colour, or appearance during the time of storage; (4) Conclusion: The pineapple juice supported the viability, lactic acid production, vitamin C development, and the antagonistic potential of the probiotic candidate. This result is useful for the development of probiotic fruit juice as functional foods and nutraceuticals with health beneficial effect. Full article

Pretreatment is the requisite step for the bioconversion of lignocellulosics. Since most of the pretreatment strategies are cost/energy intensive and environmentally hazardous, there is a need for the development of an environment-friendly pretreatment process. An ionic liquid (IL) based pretreatment approach has recently emerged as the most appropriate one as it can be accomplished under ambient process conditions. However, IL-pretreated biomass needs extensive washing prior to enzymatic saccharification as the enzymes may be inhibited by the residual IL. This necessitated the exploration of IL-stable saccharification enzymes (cellulases). Current study aims at optimizing the bioprocess variables viz. carbon/nitrogen sources, medium pH and fermentation time, by using a Design of Experiments approach for achieving enhanced production of ionic liquid tolerant cellulase from a bacterial isolate Bacillus subtilis SV1. The cellulase production was increased by 1.41-fold as compared to that under unoptimized conditions. IL-stable cellulase was employed for saccharification of IL (1-ethyl-3-methylimidazolium methanesulfonate) pretreated pine needle biomass in a newly designed bioprocess named as “one pot consolidated bioprocess” (OPCB), and a saccharification efficiency of 65.9% was obtained. Consolidated bioprocesses, i.e., OPCB, offer numerous techno-economic advantages over conventional multistep processes, and may potentially pave the way for successful biorefining of biomass to biofuel, and other commercial products. Full article

Yeast nanobiotechnology is a recent field where nanotechniques are used to manipulate and analyse yeast cells and cell constituents at the nanoscale. The aim of this review is to give an overview and discuss nanobiotechnological analysis and manipulation techniques that have been particularly applied to yeast cells. These techniques have mostly been applied to the model yeasts Saccharomyces cerevisiae and Schizosaccaromyces pombe, and the pathogenic model yeast Candida albicans. Nanoscale imaging techniques, such as Atomic Force Microscopy (AFM), super-resolution fluorescence microscopy, and electron microscopy (scanning electron microscopy (SEM), transmission electron microscopy (TEM), including electron tomography) are reviewed and discussed. Other nano-analysis methods include single-molecule and single-cell force spectroscopy and the AFM-cantilever-based nanomotion analysis of living cells. Next, an overview is given on nano/microtechniques to pattern and manipulate yeast cells. Finally, direct contact cell manipulation methods, such as AFM-based single cell manipulation and micropipette manipulation of yeast cells, as well as non-contact cell manipulation techniques, such as optical, electrical, and magnetic cells manipulation methods are reviewed. Full article