Beer is the most popular low-alcohol beverage consumed in large amounts in many countries each year. The brewing industry is an important global business with huge annual revenues. It is profitable and important for the economies of many countries around the world. The brewing process involves several steps, which lead to fermentation of sugars contained in malt and conversion thereof into alcohol and carbon dioxide by yeasts. Beer brewing generates substantial amounts of by-products. The three main brewing industry wastes include brewer’s spent grain, hot trub, and residual brewer’s yeast. Proper management of these wastes may bring economical benefits and help to protect the environment from pollution caused by their excessive accumulation. The disposal of these wastes is cumbersome for the producers, however they are suitable for reuse in the food industry. Given their composition, they can serve as a low-cost and highly nutritional source of feed and food additives. They also have a potential to be a cheap material for extraction of compounds valuable for the food industry and a component of media used in biotechnological processes aimed at production of compounds and enzymes relevant for the food industry.

Microorganisms have been harnessed to process raw plants into fermented foods. The adaptation to a variety of plant environments has resulted in a nearly inseparable association between the bacterial species and the plant with a characteristic chemical profile. Lactic acid bacteria, which are known for their ability to adapt to nutrient-rich niches, have altered their genomes to dominate specific habitats through gene loss or gain. Molecular biology approaches provide a deep insight into the evolutionary process in many bacteria and their adaptation to colonize the plant matrix. Knowledge of the adaptive characteristics of microorganisms facilitates an efficient use thereof in fermentation to achieve desired final product properties. With their ability to acidify the environment and degrade plant compounds enzymatically, bacteria can modify the textural and organoleptic properties of the product and increase the bioavailability of plant matrix components. This article describes selected microorganisms and their competitive survival and adaptation in fermented fruit and vegetable environments. Beneficial changes in the plant matrix caused by microbial activity and their beneficial potential for human health are discussed as well.

The main tenets of the sustainable food production model are to reduce the adverse environmental impacts of production and to use available resources more efficiently. The sustainable food production model allows companies to adapt their strategies to current challenges and requirements while maintaining long-term production stability and competitiveness. To ensure that sustainable food chain participants implement appropriate practices, research is being conducted to develop new solutions. Among the important issues that are of great interest to researchers is the use of lactic acid bacteria (LAB). These bacteria play a pivotal role in sustainable food production, encompassing environmental, economic, and social aspects. The following article highlights recent innovations and advancements in LAB applications, contributing to enhanced efficiency and sustainable development of food products. By fermenting food, LAB effectively enhances food safety, prolong shelf life, and augment nutritional values, while simultaneously eliminating or outcompeting foodborne pathogens, thus preventing food poisoning. This article underscores these often-overlooked aspects of LAB, such as the critical role of fermented food in sustaining humanity during challenging times, by providing essential nutrients, and supporting health through its unique preservative and probiotic properties. It also points out the lesser-known applications of these microorganisms, including the degradation of organic waste or biogas and bioplastics production.

The acidic exopolysaccharide (EPS) produced by Rhizobium leguminosarum bv. trifolii is required for the establishment of effective symbiosis with compatible host plants (Trifolium spp.). In the rhizobium-legume interaction, early stages of root infection and nodule development have been well studied from a genetic standpoint. However, factors important for colonization of several surfaces by rhizobia, including soil particles and roots, have not yet been thoroughly investigated. The aim of this study was establishing of environmental factors affecting production of EPS by R. leguminosarum bv. trifolii strain 24.2 and the role of this polysaccharide in bacterial surface properties and attachment ability.

Rhizobium leguminosarum bv. trifolii is a soil bacterium capable of establishing a symbiotic relationship with red clover (Trifolium pratense). The presence of surface polysaccharides and other extracellular components as well as motility and competitiveness are essential traits for both adaptation of this bacterium to changing environmental conditions and successful infection of host plant roots. The R. leguminosarum bv. trifolii rosR gene encodes a protein belonging to the family of Ros/MucR transcriptional regulators, which contain a Cys2His2-type zinc-finger motif and are involved in the regulation of exopolysaccharide synthesis in several rhizobial species. Previously, it was established that a mutation in the rosR gene significantly decreased exopolysaccharide synthesis, increased bacterial sensitivity to some stress factors, and negatively affected infection of clover roots. RNA-Seq analysis performed for the R. leguminosarum bv. trifolii wild-type strain Rt24.2 and its derivative Rt2472 carrying a rosR mutation identified a large number of genes which were differentially expressed in these two backgrounds. A considerable majority of these genes were up-regulated in the mutant (63.22 %), indicating that RosR functions mainly as a repressor. Transcriptome profiling of the rosR mutant revealed a role of this regulator in several cellular processes, including the synthesis of cell-surface components and polysaccharides, motility, and bacterial metabolism. Moreover, it was established that the Rt2472 strain was characterized by a longer generation time and showed an increased aggregation ability, but was impaired in motility as a result of considerably reduced flagellation of its cells. The comparative transcriptome analysis of R. leguminosarum bv. trifolii wild-type Rt24.2 and the Rt2472 mutant identified a set of genes belonging to the RosR regulon and confirmed the important role of RosR in the regulatory network. The data obtained in this study indicate that this protein affects several cellular processes and plays an important role in bacterial adaptation to environmental conditions.