Isolation, identification, and tolerance analysis of yeast during the natural fermentation process of Sidamo coffee beans.

Yeast, which plays a pivotal role in the brewing, food, and medical industries, exhibits a close relationship with human beings. In this study, we isolated and purified 60 yeast strains from the natural fermentation broth of Sidamo coffee beans to screen for indigenous beneficial yeasts. Among them, 25 strains were obtained through morphological characterization on nutritional agar medium from Wallerstein Laboratory (WL), with molecular biology identifying Saccharomyces cerevisiae strain YBB-47 and the remaining 24 yeast strains identified as Pichia kudriavzevii. We investigated the fermentation performance, alcohol tolerance, SO2 tolerance, pH tolerance, sugar tolerance, temperature tolerance, ester production capacity, ethanol production capacity, H2S production capacity, and other brewing characteristics of YBB-33 and YBB-47. The results demonstrated that both strains could tolerate up to 3% alcohol by volume at a high sucrose mass concentration (400 g/L) under elevated temperature conditions (40 ℃), while also exhibiting a remarkable ability to withstand an SO2 mass concentration of 300 g/L at pH 3.2. Moreover, S. cerevisiae YBB-47 displayed a rapid gas production rate and strong ethanol productivity. whereas P. kudriavzevii YBB-33 exhibited excellent alcohol tolerance. Furthermore, this systematic classification and characterization of coffee bean yeast strains from the Sidamo region can potentially uncover additional yeasts that offer high-quality resources for industrial-scale coffee bean production.

Investigation on screening, identification, and fermentation characteristics of Yunnan olive in the fermented liquid utilizing five strains of Saccharomyces cerevisiae.

Refined indigenous Saccharomyces cerevisiae can enhance refinement, sophistication, and subtlety of fruit wines by showcasing exceptional regional characteristics. In order to identify exceptional indigenous S. cerevisiae strains from Yunnan olive, this study isolated 60 yeast strains from wild Yunnan olive fermentation mash. The five S. cerevisiae strains were subjected to morphological and molecular biological identification, followed by evaluation of their fermentation performance, ethanol production capacity, ester production capacity, H2S production capacity, killing capacity, and tolerance. Strains LJM-4, LJM-10, and LJM-26 exhibited robust tolerance to 6% ethanol volume fraction, pH 2.8, sucrose concentration of 400 g/L, SO2 concentration of 0.3 g/L, glucose concentration of 400 g/L at both 40 °C and 15 °C. Additionally, strain LJM-10 demonstrated a faster fermentation rate compared to the other strains. Among the tested S. cerevisiae strains evaluated in this study for olive wine fermentation process in Yunnan region; strain LJM-10 displayed superior abilities in terms of ester and ethanol production while exhibiting the lowest H2S production levels. These findings suggest that strain LJM-10 holds great potential as an excellent candidate for optimizing fruit wine S. cerevisiae fermentation processes in Yunnan olive fruit wine.

Psychromicrobium Xiongbiense sp. nov., an Actinobacterium Isolated from Forest Soil.

A novel Gram-stain-positive, oval-shaped, and non-flagellated bacterial strain YIM S02556T was isolated from forest soil in Xiongbi Town, Shizong County, Qujing City, Yunnan Province, southwestern China. The strain exhibited high pairwise 16 S rRNA gene sequence similarity with Psychromicrobium lacuslunae (97.3%) and Psychromicrobium silvestre (96.3%). Strain YIM S02556T exhibited an average nucleotide identity (ANI) of 72.5% with P. lacuslunae IHBB 11,108T and 72.8% ANI with P. silvestre AK 20-18T. The digital DNA-DNA hybridization (dDDH) value between strain YIM S02556T and P. lacuslunae IHBB 11,108T was 20.2%, while with P. silvestre AK 20-18T, the dDDH value was 20.8%. Strain YIM S02556T exhibited optimal growth at 28 °C, pH 7.0, without NaCl. Growth occurred within 10-37 ℃, pH 5.0-8.0, and in the presence of up to 5% w/v NaCl concentration. The genome size was 3.1 Mbp with 64.2% G + C content. The predominant menaquinone was MK-8(H4). The major cellular fatty acid was anteiso-C15:0. Based on the polyphasic analysis, strain YIM S02556T (= KCTC 49,805T = CCTCC AB2020166T) represents a novel Psychromicrobium species in which the name Psychromicrobium xiongbiense sp.nov. was proposed.

Cultivar-specific response of rhizosphere bacterial community to uptake of cadmium and mineral elements in rice (Oryza sativa L.).

Toxic metal-contaminated farmland from Cadmium (Cd) can enhance the accumulation of Cd and impair the absorption of mineral elements in brown rice. Although several studies have been conducted on Cd exposure on rice, little has been reported on the relationship between Cd and mineral elements in brown rice and the regulatory mechanism of rhizosphere microorganisms during element uptake. Thus, a field study was undertaken to screen japonica rice cultivars with low Cd and high mineral elements levels, analyze the quantitative relationship between Cd and seven mineral elements, and investigate the cultivar-specific response of rice rhizosphere bacterial communities to differences in Cd and mineral uptake in japonica rice. Results showed that Huaidao-9 and Xudao-7 had low Cd absorption and high amounts of mineral nutrient elements (Fe, Zn, Mg, and Ca, LCHM group), whereas Zhongdao-1 and Xinkedao-31 showed opposite accumulation characteristics (HCLM group). Stepwise regression analysis showed that zinc, iron, and potassium are the key minerals that affect Cd accumulation in japonica rice and zinc was the most important factor, accounting for 68.99 %. The accumulation of Cd and mineral elements is potentially associated with rhizosphere soil bacteria. Taxa enriched in the LCHM rhizosphere (phyla Acidobacteriota and MBNT15) indicated the high nutrient characteristics of the soil and reduced activity of Cd in soil. The HCLM rhizosphere was highly colonized by metal-activating bacteria (Actinobacteria), lignin-degrading bacteria (Actinobacteria and Chlorofexi), and bacteria scavenging nutrients and trace elements (Anaerolinea and Ketobacter). Moreover, the differences in the uptake of Cd and mineral elements affected predicted functions of microbial communities, including sulfur oxidation and sulfur derivative formation, human or plant pathogen, and functions related to the iron oxidation and nitrate reduction. The results indicate a potential association of Cd and mineral elements uptake and accumulation with rhizosphere bacteria in rice, thus providing theoretical basis and a new perspective on the maintenance of rice security and high quality simultaneously.

Selection of low-cadmium and high-micronutrient wheat cultivars and exploration of the relationship between agronomic traits and grain cadmium.

The cadmium (Cd) and micronutrient contents in grains were used as screening indicators through a pot experiment, and the hierarchical cluster analysis was used to select wheat cultivars with low Cd and high micronutrient contents. The potential human health risks caused by wheat intake and the relationship between the Cd concentration in wheat grains and 12 agronomic traits were also investigated using the risk assessment model and logistic equation fitting, respectively. Yannong-23, Zhongmmai-175, and Luyuan-502, the main wheat cultivars promoted in the Huang-Huai-Hai region of China, were screened for low Cd accumulation and high micronutrient. Health risk assessment results demonstrated that children showed a high noncarcinogenic risk and that adults posed a high carcinogenic risk. The results of the agronomic trait analysis showed that low-Cd accumulation wheat cultivars had high spikelet number and fresh and dry weights of root, stem, and leaf (p < 0.05). Logistic curve fitting results showed that among all agronomic traits, the root dry weight was the most suitable factor with remarkable goodness of fit and showed a significant negative correlation. The Cd concentration in wheat grains could be predicted by the logistic curve equation obtained by fitting this trait. Results provided theoretical support for the safe use of slightly to moderately contaminated farmland, formulation of health risk management policies for different populations, and breeding of high-quality wheat.

Screening stably low cadmium and moderately high micronutrients wheat cultivars under three different agricultural environments of China.

Heavy metal-contaminated farmland, especially for cadmium (Cd), is being used for agricultural production in large scale due to the increasing food demand. Thus, minimizing the influx of Cd to the human food chain is urgently needed. Screening for stably low Cd and moderately high micronutrient wheat cultivars is one of the most feasible and effective approaches to ensure food safety and quality. Here, the Cd accumulation by 72 wheat cultivars was identified in field 1, and the stability of Cd accumulation in these cultivars was tested in fields 2 and 3. The effects of Cd on micronutrient (zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), and boron (B)) uptake in grains were also investigated. Nine of the 24 low-Cd wheat cultivars identified by screening showed stably low-Cd and moderately high micronutrient concentrations in grain. Nine cultivars exhibited unstable low-Cd accumulation characteristics, and another five cultivars contained significantly lower Zn concentrations in grain in at least two experimental fields. One low-Cd cultivar also had low Zn, Cu and Mn concentrations in grain. The accumulation of Cd in wheat grain had little effects on the uptake of Fe. Grain Cd concentration correlated positively with the dry weight of stem and root, and negatively with the spike length. There was no correlation between grain Cd concentration and wheat yield. The selected cultivars with stably low-Cd accumulation and moderately high micronutrient concentrations in grain are recommended for cultivation in slightly to moderately Cd-contaminated farmland to ensure food safety for the growing human population.