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Azospirillum is one of the most studied plant growth-promoting bacteria (PGPB); it represents a common model for plant-bacterial interactions. While Azospirillum brasilense is the species that is most widely known, at least 22 species, including 17 firmly validated species, have been identified, isolated from agricultural soils as well as habitats as diverse as contaminated soils, fermented products, sulfide springs, and microbial fuel cells. Over the last 40 years, studies on Azospirillum-plant interactions have introduced a wide array of mechanisms to demonstrate the beneficial impacts of this bacterium on plant growth. Multiple phytohormones, plant regulators, nitrogen fixation, phosphate solubilization, a variety of small-sized molecules and enzymes, enhanced membrane activity, proliferation of the root system, enhanced water and mineral uptake, mitigation of environmental stressors, and competition against pathogens have been studied, leading to the concept of the Multiple Mechanisms Hypothesis. This hypothesis is based on the assumption that no single mechanism is involved in the promotion of plant growth; it posits that each case of inoculation entails a combination of a few or many mechanisms. Looking specifically at the vast amount of information about the stimulatory effect of phytohormones on root development and biological nitrogen fixation, the Efficient Nutrients Acquisition Hypothesis model is proposed. Due to the existence of extensive agriculture that covers an area of more than 60 million hectares of crops, such as soybeans, corn, and wheat, for which the bacterium has proven to have some agronomic efficiency, the commercial use of Azospirillum is widespread in South America, with over 100 products already in the market in Argentina, Brazil, and Uruguay. Studies on Azospirillum inoculation in several crops have shown positive and variable results, due in part to crop management practices and environmental conditions. The combined inoculation of legumes with rhizobia and Azospirillum (co-inoculation) has become an emerging agriculture practice in the last several years, mainly for soybeans, showing high reproducibility and efficiency under field conditions. This review also addresses the use of Azospirillum for purposes other than agriculture, such as the recovery of eroded soils or the bioremediation of contaminated soils. Furthermore, the synthetic mutualistic interaction of Azospirillum with green microalgae has been developed as a new and promising biotechnological application, extending its use beyond agriculture.

Fermentation is an ancient technique for preserving food and feed, and for moderating taste and texture of foods. Fermentation of seaweeds for generating novel food products has yet only been described for few red algae. Here, sugar kelp (Saccharina latissima) was heat-treated and fermented using lactic acid bacteria (LAB). Taste, smell and texture of the fermented product was compared to fresh sugar kelp and two commercial seaweed products (nori and wakame). Tissue contents of dry matter, nitrogen, mannitol, and selected minerals and trace metals of the fresh and fermented sugar kelp were quantified and compared. In the fermentation process, the pH was reduced to 4.5 within 40 h, with LAB counts increasing 100-fold and no Bacillus cereus present. Heat-treatment and fermentation caused a reduced saltiness and umami flavour of the sugar kelp, a less slimy visual appearance and a reduced smell of sea, whereas the texture and protein content was unchanged compared to the fresh sugar kelp. The fermented sugar kelp had a stronger bite than nori and wakame, a stronger smell of sea and a more salty, irony and umami rich taste than nori, but less umami and salt taste than wakame. The fermentation process reduced the contents of sodium (− 15%), cadmium (− 35%) and mercury (− 37%) in the sugar kelp. LAB fermentation of sugar kelp showed promising for broadening the food market for seaweeds as the fermented product had a milder taste, improved visual impression and smell, and a reduced content of harmful trace metals.

Aquaculture reliance on fishmeal protein has become a bottleneck due to long-term sustainability concerns and increasing costs. Given its abundance and nutrient-rich profile, the green macroalga Ulva rigida is a promising alternative protein source. However, the bioaccessibility of its proteins is hindered by an embedding matrix of ulvan, a gel-forming polysaccharide. Saccharification of the alga crude fiber followed by microbial fermentation improves protein bioaccessibility and leads to products of higher protein content and quality. Also, upon fermentation, the nutritional and bioactive properties of these feed ingredients are enhanced, since microorganisms synthesize vitamins, new proteins, and essential amino acids. The carbohydrate fraction of Ulva rigida was hydrolyzed into a sugar-rich syrup and subsequently used as a substrate in microbial fermentations. Three types of fermentation were tested, namely, with a consortium of four lactic acid bacteria (LAB), with Saccharomyces cerevisiae, and with a co-culture of lactobacilli and yeast. A functional analysis of lyophilized whole-fermentation broths revealed that the yeast-fermented products had stronger antioxidant properties when compared to the LAB-fermented products. The protein bioaccessibility in the fermented products was 11- to 12-fold higher than that of the raw alga. These findings highlight the potential of utilizing S. cerevisiae and lactobacilli starter cultures in seaweed fermentation to produce Ulva-based feed ingredients.

In shrimp farming, the development of alternative production systems, such as fermented products, can help reduce the high dependence on artificial diets and ensure more sustainable growth. The “synbiotic system” typically uses low stocking densities in traditional earth ponds. To increase profitability, the tendency is to increase stocking densities, especially in small production units. The objective of the following work was to use the “synbiotic system” in different stocking densities, analyzing the water quality, the microorganisms present, the proximal composition of the formed bioflocs and the zootechnical performance. For this, 12 tanks with an area of 35 m 2 each were used. Stocking densities were 30, 60, 90 and 120 shrimp/m 2 . Fertilization was carried out for seven days before the shrimp stocking and then every two days until the end of the experiment. The experiment lasted 45 days, and no water was renewed. Significant differences were observed in several quality parameters, including alkalinity, nitrate, total suspended solids, and turbidity. However, no significant differences were found in the proximal composition of the formed bioflocs. The presence of microorganisms throughout the experimental period indicated the effectiveness of adding fermented rice bran for nutrient assimilation. Furthermore, significant differences were observed in the final weight, feed conversion rate and productivity. The ability of the synbiotic system to provide food supplementation, control water quality and present satisfactory zootechnical performance was demonstrated, proving to be efficient in the cultivation of Litopenaeus vannamei .

Triatomines (Hemiptera: Heteroptera: Reduviidae) are hematophagous insects, well-known for their vectorial role in transmitting Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae) parasites, the etiological agent of Chagas disease. Trapping these insects would limit human-triatomine interaction and, thus, control the disease. In this context, there is a critical need for effective lures to control triatomines. Through double-choice bioassays, we investigated the preference of Triatoma infestans Klug, T. pallidipennis Stal, and Rhodnius prolixus Stal triatomines for: (a) volatiles from fermented products (various fermentation types and substrates) and (b) commercial insect lures. Furthermore, we identified the chemical composition of these volatiles through headspace collection using Solid Phase Micro Extraction coupled with Gas Chromatograph-Mass Spectrometer (HS-SPME-GC-MS). Volatiles from lactic fermentation and certain fermented fruits, along with commercial lures, attracted triatomines, while other products exhibited possible repellent or dislodging properties. These findings hold promise for the control of triatomines and, ultimately, Chagas disease.

The mold Monascus, also called red yeast rice, anka, or koji, has been used as the natural food coloring agent and food additives for more than 1000 years in Asian countries. It has also been used in Chinese herbology and traditional Chinese medicine due to its easing digestion and antiseptic effects. However, under different culture conditions, the ingredients in Monascus-fermented products may be changed. Therefore, an in-depth understanding of the ingredients, as well as the bioactivities of Monascus-derived natural products, is important. Here, through the thorough investigation into the chemical constituents of M. purpureus wmd2424, five previously undescribed compounds, monascuspurins A–E (1–5), were isolated from the EtOAc extract of mangrove-derived fungus Monascus purpureus wmd2424 cultured in RGY medium. All the constituents were confirmed via HRESIMS and 1D- and 2D-NMR spectroscopy. Their antifungal activity was also evaluated. Our results showed that four constituents (compounds 3–5) possessed mild antifungal activity against Aspergillus niger, Penicillium italicum, Candida albicans, and Saccharomyces cerevisiae. It is worth mentioning that the chemical composition of the type strain Monascus purpureus wmd2424 has never been studied.

Agar-based disc diffusion antimicrobial assay has shown that the ethyl acetate extract of the fermented broth of Aspergillus giganteus NTU967 isolated from Ulva lactuca exhibited significant antimicrobial activity in our preliminary screening of bioactive fungal strains. Therefore, column chromatography of the active principles from liquid- and solid–state fermented products of the fungal strain was carried out, and which had led to isolation of eleven compounds. Their structures were determined by spectral analysis to be seven new highly oxygenated polyketides, namely aspergilsmins A–G (1–7), along with previously reported patulin, deoxytryptoquivaline, tryptoquivaline and quinadoline B. Among these, aspergilsmin C (3) and patulin displayed promising anticancer activities against human hepatocellular carcinoma SK-Hep-1 cells and prostate cancer PC-3 cells with IC50 values between 2.7–7.3 μM. Furthermore, aspergilsmin C (3) and patulin exhibited significant anti-angiogenic functions by impeding cell growth and tube formation of human endothelial progenitor cells without any cytotoxicity.

In this study, dried sheets of nori, shredded and processed thalli of the red alga Pyropia yezoensis, were fermented with either barley, rice or soybean koji. High-performance liquid chromatographic analyses of the lipid extracts of the fermented products indicated that the fermentation of nori with all kinds of tested koji released free fatty acids, including the eicosapentaenoic acid, from ester lipids. We found that approximately half of the eicosapentaenoic acid in nori had been released as the free fatty acid at up to 4 weeks of fermentation at 30 °C and more than 65% at 8 to12 weeks in the fermented products with barley and rice koji. We also demonstrated the degradation of porphyran, a major cell wall polysaccharide of nori, by gel chromatography on Sephacryl S-300 HR of hot water extracts of the fermented products of nori with barley koji. Approximately two-third of porphyran had been degraded to porphyran oligosaccharides up to 6 weeks of fermentation. Fermentation of nori with koji may bring out the potential health-promoting functions of nori.

Koji is commonly used in manufacturing Japanese fermented products and promotes enzymatic degradation. In recent years, a seaweed koji has been developed by culturing Aspergillus oryzae on nori Pyropia yezoensis. In the present study, we prepared nori koji by culturing A. oryzae on high- and low-quality noris and then mixing this preparation with additional dried nori. Suitable fermentation conditions for increasing the taste-active components of the nori mixed with nori koji were investigated. The mixture of nori and koji prepared from high-quality nori, with added water, cultured for 120 days at 10 °C, provided the greatest increase (7 times) in free amino acids. The changes in taste after culturing the nori and koji mixture were evaluated using a taste-sensing system. The sourness score of the nori and koji mixture increased significantly, but the scores for other attributes such as bitterness and umami richness did not increase after culture. The present study has demonstrated a clear increase in the free amino acid content of nori and a modification in the taste score by aging the culture with nori koji. These results will encourage the development of ‘aged seaweed,’ a novel value-added product with nutritional and taste elements modified using seaweed koji.

The supernatants (the solution part received after centrifugation) of squid pens fermented by four species of Paenibacillus showed potent inhibitory activity against α-glucosidases derived from yeast (79–98%) and rats (76–83%). The inhibition of acarbose—a commercial antidiabetic drug, used against yeast and rat α-glucosidases—was tested for comparison; it showed inhibitory activity of 64% and 88%, respectively. Other chitinolytic or proteolytic enzyme-producing bacterial strains were also used to ferment squid pens, but no inhibition activity was detected from the supernatants. Paenibacillus sp. TKU042, the most active α-glucosidase inhibitor (aGI)-producing strain, was selected to determine the optimal cultivation parameters. This bacterium achieved the highest aGI productivity (527 µg/mL) when 1% squid pens were used as the sole carbon/nitrogen source with a medium volume of 130 mL (initial pH 6.85) in a 250 mL flask (48% of air head space), at 30 °C for 3–4 d. The aGI productivity increased 3.1-fold after optimization of the culture conditions. Some valuable characteristics of Paenibacillus aGIs were also studied, including pH and thermal stability and specific inhibitory activity. These microbial aGIs showed efficient inhibition against α-glucosidases from rat, yeast, and bacteria, but weak inhibition against rice α-glucosidase with IC50 values of 362, 252, 189, and 773 µg/mL, respectively. In particular, these aGIs showed highly stable activity over a large pH (2–13) and temperature range (40–100 °C). Various techniques, including: Diaoin, Octadecylsilane opened columns, and preparative HPLC coupled with testing bioactivity resulted in isolating a main active compound; this major inhibitor was identified as homogentisic acid (HGA). Notably, HGA was confirmed as a new inhibitor, a non-sugar-based aGI, and as possessing stronger activity than acarbose with IC50, and maximum inhibition values of 220 μg/mL, 95%, and 1510 μg/mL, 65%, respectively. These results suggest that squid pens, an abundant and low-cost fishery processing by-product, constitute a viable source for the production of antidiabetic materials via fermentation by strains of Paenibacillus. This fermented product shows promising applications in diabetes or diabetes related to obesity treatment due to their stability, potent bioactivity, and efficient inhibition against mammalian enzymes.