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Kombucha, one of the ordinary fermented beverages consumed worldwide, is produced by fermenting tea and sugar with a symbiotic culture of bacteria and yeasts or so-called SCOBY. Kombucha can be made from different types of tea, such as black, green, white, red, and oolong teas, yielding various health benefits and properties. Several species of bacteria and yeasts are involved in the fermentation process, which generates many beneficial compounds, such as polyphenols, organic acids, amino acids, vitamins, minerals, organic nitrogens, and hydrolytic enzymes, which have significant health effects and therapeutic properties, such as antioxidant, anti-inflammatory, anticancer, and antimicrobial properties. This review describes recent research on kombucha fermentation, the microbial community in SCOBY, the chemical composition of kombucha, and its health benefits. The adverse effects and prospects of kombucha production were also discussed.

Enzymes excreted by rumen microbiome facilitate the conversion of ingested plant materials into major nutrients (e.g., volatile fatty acids (VFA) and microbial proteins) required for animal growth. Diet, animal age, and health affect the structure of the rumen microbial community. Pathogenic organisms in the rumen negatively affect fermentation processes in favor of energy loss and animal deprivation of nutrients in ingested feed. Drawing from the ban on antibiotic use during the last decade, the livestock industry has been focused on increasing rumen microbial nutrient supply to ruminants through the use of natural supplements that are capable of promoting the activity of beneficial rumen microflora. Selenium (Se) is a trace mineral commonly used as a supplement to regulate animal metabolism. However, a clear understanding of its effects on rumen microbial composition and rumen fermentation is not available. This review summarized the available literature for the effects of Se on specific rumen microorganisms along with consequences for rumen fermentation and digestibility. Some positive effects on total VFA, the molar proportion of propionate, acetate to propionate ratio, ruminal NH3-N, pH, enzymatic activity, ruminal microbiome composition, and digestibility were recorded. Because Se nanoparticles (SeNPs) were more effective than other forms of Se, more studies are needed to compare the effectiveness of synthetic SeNPs and lactic acid bacteria enriched with sodium selenite as a biological source of SeNPs and probiotics. Future studies also need to evaluate the effect of dietary Se on methane emissions.

Temperature plays a significant role in anaerobic digestion (AD) as it affects the microbial communities and ultimately controls the efficiency of the process. Few studies have looked at temperature-adjusted AD, but it is unclear how the temperature shifts affect biogas production and the dynamics of microorganisms involved in methanogenesis. This study tested two temperature shift scenarios in fed-batch mode using anaerobically digested sewage sludge and glucose-based substrate. The first scenario was acclimatized to upshifting temperatures from 42 °C to 48 °C while the second was acclimatized to downshifting temperatures from 55 °C to 45 °C. Both temperature shift scenarios resulted in a decrease in biogas production, especially at 45 °C. The upshifted scenario experienced a maximum decrease of 83%, and the downshifted scenario experienced a 16–33% decrease in methane production. Next-generation 16S rRNA sequencing revealed the domination of Methanoculleus in the upshifted scenario. However, a low correlation between the number of Methanoculleus and the other hydrogenotrophic methanogens to biogas production indicates inhibition in the hydrogenotrophic pathway. The downshifted scenario showed better biogas production due to the substantial domination of acetoclastic Methanosaeta and the low abundance of sulfate-reducing bacteria. Hence, the temperature shift affects the microbial communities, significantly affecting biogas production performance.

This review discusses the recent advancements in cost-effective fermentation methods for producing bacterial nanocellulose (BC) from food and agro-industrial waste. Achieving economical cell culture media is crucial for large-scale BC production, requiring nutrient-rich media at low cost to maximize cellulose yield. Various pretreatment methods, including chemical, physical, and biological approaches, are stated to break down waste into accessible molecules for cellulose-producing bacteria. Additionally, strategies such as dynamic bioreactors and genetic engineering methods are investigated to enhance BC production. This review also focuses on the environmental impact assessment and updated application challenges of BC such as medical applications, energy storage/electronics, filtration membranes, and food packaging. By providing insights from the recent literature findings, this review highlights the innovative potential and challenges in economically and efficiently producing BC from waste streams.

Coffee pulp, mucilage, and beans with mucilage were used to develop alcoholic beverages. The pulp of 45.3% pulp, 54.7% mucilage with seed, and 9.4% mucilage only were obtained during the wet processing of coffee. Musts were prepared for all to TSS (Total soluble solid) 18 °Bx and fermentation was carried out for 12–16 days until TSS decreased to 5 °Bx at 30 °C. Phenolic characteristics, chromatic structures, chemical parameters, and sensory characteristics were analyzed for the prepared alcoholic beverages. Methanol content, ester content, aldehyde, alcohol, total acidity, caffeine, polyphenols, flavonoids, chromatic structure, and hue of the alcoholic beverage from the pulp was 335 mg/L, 70.58 ppm, 9.15 ppm, 8.86 ABV%, 0.41%, 30.94 ppm, 845.7 mg GAE/g dry extract, 440.7 mg QE/g dry extract, 0.41, and 1.71, respectively. An alcoholic beverage from the pulp was found superior to an alcoholic beverage from mucilage with beans and a beverage from mucilage in sensory analysis. There is the possibility of developing fermented alcoholic beverages from coffee pulp and mucilage. However, further research is necessary for quality of the beans that were obtained from the fermentation with the mucilage.

The optimum fermentation conditions for ethanol production from sweet sorghum juice (SSJ) by the thermotolerant yeast Saccharomyces cerevisiae DBKKUY-53 were determined using a statistical experimental design. Based on the Plackett–Burman design (PBD), yeast cell concentration, sugar concentration, and yeast extract were the significant independent fermentation factors affecting the ethanol production from SSJ at 37 °C by S. cerevisiae DBKKUY-53. These significant factors were optimized using response surface methodology (RSM) based on a central composite design (CCD). The result revealed that the optimum conditions for ethanol fermentation were 7.85 × 107 cells/mL yeast cell concentration, 247 g/L sugar concentration, and 9.99 g/L yeast extract. Verification of the ethanol production using the optimum conditions revealed that the maximum ethanol concentration of 99.75 g/L and the productivity of 2.77 g/L/h were achieved. When the ethanol production was carried out in a 2 L fermentor under optimum conditions, the ethanol concentration was 101.81 g/L and the productivity was 2.83 g/L/h. This finding suggested that the thermotolerant yeast S. cerevisiae DBKKUY-53 has excellent potential for commercial ethanol production at high temperatures.

Spent coffee waste is the most common by-product of coffee processing, and it has the potential to be used as a source of organic compounds for ruminant diets. The objective of this study was to evaluate the optimal inclusion level and method for using spent coffee waste (SCW) as a ruminant feed and investigate its effects on rumen fermentation characteristics and methane (CH4) production. The present in vitro batch culture study was conducted using two different experimental designs. The first experimental design (TRIAL. 1) was performed using a control diet of 500 mg of fresh matter basal diet (60% hay/40% concentrate), with SCW being used as a feed additive at 1%, 10% and 20% of the substrate. The second experimental design was performed using the same control diet, with spent coffee waste replacing either part of the hay (TRIAL. 2) or some of the concentrate mixture (TRIAL. 3) at four different dosages (30:70, 50:50, 70:30 and 100). When SCW was supplemented as a feed additive, there were increases in the production of volatile fatty acids and gas; however, it did not show any suppressive effects on CH4 production. In contrast, when SCW was included as a replacement for hay or concentrate, there were significant reductions in CH4 production with increasing levels of SCW inclusion. These reductions in CH4 production were accompanied by negative effects on nutrient digestibility and total volatile fatty acid production. These findings demonstrate that SCW could potentially be used as a prebiotic feed additive. Additionally, when SCW is used as a replacement for silage at 70:30 and 50:50 dosages appear to be feasible as a substitute for animal feed (hay and concentrate).

This study investigated the impacts of different brown seaweed species—Ascophyllum nodosum, Sargassum fulvellum, Ecklonia maxima, Lessonia flavicans, Lessonia nigrescens, and Laminaria japonica—on rumen fermentation and methane (CH4) mitigation. The current in vitro batch culture study for 24 h at 39 °C evaluated these species in two experimental designs: as feed additive and as feed. The control group for both experimental designs was composed of 500 mg of basal diet (50% grass hay/50% concentrate). For the feed additives experimental design, each seaweed species was evaluated when it was added at 20% of the basal diet, while as a feed, the inclusion level of each species was 20% to partially replace the concentrate in the basal diet as follows (50% hay/30% concentrate/20% seaweed). Chemical analyses showed that the seaweeds were characterized by a high fiber content and high amounts of minerals such as calcium, potassium, and phosphorus, while the protein content ranged within 7 and 13%. When they were applied as feed additives, they increased the production of volatile fatty acids, with L. japonica being the most effective; however, they failed to suppress CH4 production. In contrast, their inclusion as a feed in the basal diet led to a significant reduction (p < 0.05) in CH4, especially for E. maxima and L. japonica, by up to 18 and 21%, respectively, but this was associated with general inhibition of the rumen fermentation. Therefore, the tested seaweeds could be used as a source of minerals and as a feed additive to improve rumen fermentation, but without anti-methanogenic potential. Meanwhile, their inclusion as feed at 20% could reduce CH4 production with an adverse effect on fermentation. Thus, further trials are needed to identify the appropriate inclusion level to achieve effective CH4 reduction without any detrimental effects on rumen fermentation.

Shrimp shell waste is a potential source of the biopolymer chitin. Through fermentation, chitin can be converted into its derivative products. This study aimed to isolate and characterize the products of the biodegradation of chitin from shrimp shell waste through a solid-state fermentation process using actinomycetes. Actinomycete isolates were obtained from tunicate marine biota collected from the waters of Buleleng, Bali, using a dilution technique on 1% chitin colloid agar medium. The isolated actinomycetes were cultivated on a shrimp shell waste medium for 7 days, and then the products of the biodegradation of the oligomers were extracted using water. The extracts of the biodegradation products of the shrimp shells were isolated through several chromatographic steps and analyzed using LC–MS–MS, and the bioactivity of the biodegradation products against fungi was tested. The morphological observations and phylogenetic analysis showed that the isolate 18D36-A1 was a rare actinomycete with the proposed name Pseudonocardia antitumoralis 18D36-A1. The results of the analysis using TLC showed that the solid-state fermented water isolate 18D36-A1 produced several oligomeric components. These results indicate that the isolate 18D36-A1 was able to convert chitin into chitooligosaccharides. Further isolation of the extract produced the active fraction D36A1C38, which can inhibit the growth of fungi by 74% at a concentration of 1 mg/mL. This initial information is very important for further studies related to the development of a solid-state fermentation process for obtaining bioactive compounds from shrimp shell waste.

Rice bran is known to have beneficial nutrients. Current studies suggest that solid-state fermentation affects the rice bran’s volatile profile. The aim of this study is to identify the volatile compounds and aroma description of fermented and nonfermented rice bran (FRB and NFRB) of Ciherang, Inpari30, IR64 and Inpari42. The fermentation was conducted using Rhizopus oligosporus solid-state fermentation. Headspace-solid phase microextraction coupled with GC/MS was performed, and the aroma was translated by 10 trained panelists through quantitative descriptive analysis (QDA). The result showed that 72 and 68 compounds were identified in FRB and NFRB, respectively. They are aldehydes, ketones, alcohols, acids, esters, fatty acid, phenol, benzenes, furan, thiazole, pyrazines, pyridine, lactones, terpenes, and hydrocarbons. The PCA showed that FRB was dominated by alcohols, whereas NFRB was dominated by aldehydes. The QDA described nine aromas, i.e., rancid, smoky, musty, grassy, green, earthy, cereal, and sweet in NFRB. The fermentation process added fermented attributes to the aroma description to FRB and enhanced the rancid, smoky, and musty aromas. These studies indicated that fermented rice bran might increase the volatile compound of rice bran. Thus, it may provide opportunities to develop the production of fermented rice bran as a functional ingredient.