Search

The massive yield of brewers' spent grain (BSG) waste inevitably threaten environmental health. Here, solid-state fermentation (SSF) technology featuring multi-strain (MS) inoculation and high-throughput sequencing technology were employed to facilitate the sustainable and clean recycling of BSG waste while revealing the associated underlying microbiological and metabolic mechanisms. MS inoculation displayed a lower pH value (3.91 vs. 4.12) and neutral detergent fiber content (446.24 vs. 476.23 g/kg DM), a higher levels of lactic acid (86.64 vs. 33.07 g/kg DM), acetic acid (6.13 vs. 4.87 g/kg DM), propionic acid (2.78 vs. 2.18 g/kg DM) and crude protein (307.5 vs. 289.15 g/kg DM) than those in the control group. Moreover, MS inoculation inhibited the formation of nonprotein- N and ammonia-N, and spoilage microorganism resuscitation, while enhanced substrate preservation. Microbiologically, during the SSF, the group treated with MS inoculation exhibited an increase in the relative abundance of Leuconostoc (0.58%-6.60%), Weissella (6.22%-15.42%), Enterococcus (3.15%-9.08%), Bacillus (17.63%-31.29%), Lactobacillus (12.89%-8.29%), Pseudoalteromonas (12.87%-16.29%), and a decrease in the relative abundance of Acinetobacter (0.79%-0.02%) and Enterobacteriaceae (0.78%-0.24%). Metabolically, starch and sucrose metabolism, arginine and proline metabolism, and phenylalanine metabolism significantly influenced the quality of extruded BSG fermented by MS during SSF. The examination of the correlation between the microbiota, metabolites, and fermentation parameters revealed that complex interactions between microbes and the environment factors impact metabolite production. Collectively, inoculating with MS improved fermentation quality and stability, facilitated the clean recycling of BSG, which is linked to complex interactions among microbes, the environment factors and metabolite production. [ABSTRACT FROM AUTHOR]

The massive yield of brewers' spent grain (BSG) waste inevitably threaten environmental health. Here, solid-state fermentation (SSF) technology featuring multi-strain (MS) inoculation and high-throughput sequencing technology were employed to facilitate the sustainable and clean recycling of BSG waste while revealing the associated underlying microbiological and metabolic mechanisms. MS inoculation displayed a lower pH value (3.91 vs. 4.12) and neutral detergent fiber content (446.24 vs. 476.23 g/kg DM), a higher levels of lactic acid (86.64 vs. 33.07 g/kg DM), acetic acid (6.13 vs. 4.87 g/kg DM), propionic acid (2.78 vs. 2.18 g/kg DM) and crude protein (307.5 vs. 289.15 g/kg DM) than those in the control group. Moreover, MS inoculation inhibited the formation of non-protein-N and ammonia-N, and spoilage microorganism resuscitation, while enhanced substrate preservation. Microbiologically, during the SSF, the group treated with MS inoculation exhibited an increase in the relative abundance of Leuconostoc (0.58%∼6.60%), Weissella (6.22%∼15.42%), Enterococcus (3.15%∼9.08%), Bacillus (17.63%∼31.29%), Lactobacillus (12.89%∼8.29%), Pseudoalteromonas (12.87%∼16.29%), and a decrease in the relative abundance of Acinetobacter (0.79%∼0.02%) and Enterobacteriaceae (0.78%∼0.24%). Metabolically, starch and sucrose metabolism, arginine and proline metabolism, and phenylalanine metabolism significantly influenced the quality of extruded BSG fermented by MS during SSF. The examination of the correlation between the microbiota, metabolites, and fermentation parameters revealed that complex interactions between microbes and the environment factors impact metabolite production. Collectively, inoculating with MS improved fermentation quality and stability, facilitated the clean recycling of BSG, which is linked to complex interactions among microbes, the environment factors and metabolite production., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Xie, Liu, Liu, Tang, Zhao, Chen, Tian, Liu, Cai and Jia.)

The conventional techniques for free cell inoculation, though inexpensive and easy to inoculate have limitations. Selection of carriers for the inoculants is crucial to support the storage of inoculants for marketing and the delivery of suitable amount of microorganism in good physiological condition. To overcome the limitations of scarcity of suitable carrier materials as well as to check the uncontrolled release of bacteria, encapsulated microorganism or alignate beads and irrigation based inocula delivery system have been developed. Apart from common inorganic, organic and polymeric compound used as carriers for microorganism delivery, research also being pursued to develop bacterial biofilms and nanoparticle based carriers. Idea of inoculation of bacteria into the plant cell suspension and their regeneration, though in infant stage, also seems to be one of the future possibilities. On the other hand, multi-strain inoculation claims to be better over single-strain inoculation. Critical and comprehensive analysis of the current knowledge of these technologies with emphasis on rice has been discussed in this review. [ABSTRACT FROM AUTHOR]