**4. Ultradisperse humic sapropel suspension (UDHSS) nanoparticles (UDHSS-NPs)**

Sapropel is benthos found in fresh water, formed under anaerobic conditions from dead organic matter of anhydrobiotic microflora and microfauna. It is principally composed of nutrients (i.e., sugars, minerals, lipids, etc.) and organic compounds known as humic substances [148–151]. Sapropels and sapropel extracts showed antibacterial and antifungal properties in previous studies hence could used as an alternate and novel biocidal agent during grain storage. The antimicrobial properties of sapropels is attributed to the presence of humic substances [152–156]. Sapropel has become a popular raw material for therapeutic applications, production of sorbents, organic fertilizers, and food supplements [157]. UDHSS-NPs are organic NPs which exhibits potent biocidal activities due to the presence of humic substances [148]. Fulvic acids (FAs), humic acids (HAs), mumie, and humin are the principal constituents of humic substances (HSs) in sapropels [158–161], and are reportedly attribute to their biocidal properties. Many studies [152–155] have illustrated the inhibitory effects of sapropel on bacteria (*S*. *aureus*, *E*. *coli*, etc.) and yeasts (*Candida*, etc.). A micrograph of UDHSS-NPs is shown in **Figure 2** however, its characteristics were not included in the present study.

In a series of tests performed by Barakova et al. [148], experiments 2 and 3 exhibited most significant fungicidal effects on *A*. *niger,* a species which poses a greater threat to grain/food industries due to the potent mycotoxins it produce. A report showed that hematite NPs (hematite-HA complexes) significantly

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**Figure 2.**

*The Potential Application of Nanoparticles on Grains during Storage: Part 2 – An Overview…*

inhibited the growth and gene expression of *P*. *putida* KT2440. The bactericidal activities were ascribed to the oxidative stress induced by generated ROS. It was also shown that the physicochemical properties of the NPs (e.g., surface charge and size) influenced the efficacy of the hematite-HA complexes [162]. Therefore,

A group of researchers [163] assessed the fungicidal activity of HAs and FAs extracted from soils on phytopathogenic fungal species (*Physalospora piricola*

(P.P), *Botrytis cinerea* (B.C), *Rhizoctonia cerealis* (R.C), *Fusarium graminearum* (F.G), *Phytophthora infestans* (P.I), *Sclerotinia sclerotiorum* (S.S), *Rhizoctonia solani* (R.S), *Cercospora arachidicola Hori* (C.H), and *Bipolaris maydis* (B.M)). The results showed that HA exhibited above 30% and 50% inhibition against B.C, R.C, F.G, P.I, and P.P, respectively. The inhibition exerted by HA on all the species was higher compared to FA except for B.C. Correlation analysis further revealed that the inhibition rates of HAs decreased significantly with time (years) (p < 0.05) against most tested fungi except P.I., whereas FAs showed a negative correlation with cultivation years

activity in zebrafish embryo. Physicochemical properties such as size, zeta potential, and particle dissolution influenced their actions. It was further shown that coupling HAs with NPs enhanced the activity of the composite NPs. The addition of HAs reduced the hydrodynamic diameters of all examined NP suspensions except cadmium selenide (CdSe) NPs. Ezhkov and colleagues [165] developed NP-sapropel composite with particle size 45.0–180.0 nm and investigated its effects on treated albino mice. The results showed scarring of organ walls and shedding/exfoliation of the superficial epithelial cells. Further histological analysis of the oesophagus wall showed a significant thinning of the horny substance and the removal of the stratified epithelium of the mucous

HA) altered enzyme

modification of UDHSS-NPs could improve its biocidal properties.

(p < 0.05) against most of the tested fungi except F.G. and S.S. Recently, Ong et al. [164] documented that HAs (10 mg L<sup>−</sup><sup>1</sup>

membranes in areas in contact with the NPs.

*UDHSS nanoparticles under a scanning electron microscope (SEM).*

*DOI: http://dx.doi.org/10.5772/intechopen.93213*

*The Potential Application of Nanoparticles on Grains during Storage: Part 2 – An Overview… DOI: http://dx.doi.org/10.5772/intechopen.93213*

inhibited the growth and gene expression of *P*. *putida* KT2440. The bactericidal activities were ascribed to the oxidative stress induced by generated ROS. It was also shown that the physicochemical properties of the NPs (e.g., surface charge and size) influenced the efficacy of the hematite-HA complexes [162]. Therefore, modification of UDHSS-NPs could improve its biocidal properties.

A group of researchers [163] assessed the fungicidal activity of HAs and FAs extracted from soils on phytopathogenic fungal species (*Physalospora piricola* (P.P), *Botrytis cinerea* (B.C), *Rhizoctonia cerealis* (R.C), *Fusarium graminearum* (F.G), *Phytophthora infestans* (P.I), *Sclerotinia sclerotiorum* (S.S), *Rhizoctonia solani* (R.S), *Cercospora arachidicola Hori* (C.H), and *Bipolaris maydis* (B.M)). The results showed that HA exhibited above 30% and 50% inhibition against B.C, R.C, F.G, P.I, and P.P, respectively. The inhibition exerted by HA on all the species was higher compared to FA except for B.C. Correlation analysis further revealed that the inhibition rates of HAs decreased significantly with time (years) (p < 0.05) against most tested fungi except P.I., whereas FAs showed a negative correlation with cultivation years (p < 0.05) against most of the tested fungi except F.G. and S.S.

Recently, Ong et al. [164] documented that HAs (10 mg L<sup>−</sup><sup>1</sup> HA) altered enzyme activity in zebrafish embryo. Physicochemical properties such as size, zeta potential, and particle dissolution influenced their actions. It was further shown that coupling HAs with NPs enhanced the activity of the composite NPs. The addition of HAs reduced the hydrodynamic diameters of all examined NP suspensions except cadmium selenide (CdSe) NPs. Ezhkov and colleagues [165] developed NP-sapropel composite with particle size 45.0–180.0 nm and investigated its effects on treated albino mice. The results showed scarring of organ walls and shedding/exfoliation of the superficial epithelial cells. Further histological analysis of the oesophagus wall showed a significant thinning of the horny substance and the removal of the stratified epithelium of the mucous membranes in areas in contact with the NPs.

**Figure 2.** *UDHSS nanoparticles under a scanning electron microscope (SEM).*

*Mycotoxins and Food Safety*

cell wall than microbes.

these factors.

**(UDHSS-NPs)**

A decrease in the induction of β-galactosidase was observed when yeast cells were exposed to chitosan. A concentration of 0.35 mg/mL chitosan reduced β-galactosidase activity by 32%. An increased in concentration (1.25 mg/mL) further led to the reduction of enzyme activity. The control experiment did not follow the trend. Likewise, the treated cells showed that chitosan greatly influenced protein biosynthesis in the yeast [130]. Previous work [143] documented cell sensitivity to chitosan, which altered the deletions of genes involved in sphingolipid (e.g., *ipt1Δ*, *skn1Δ*, *lcb3Δ*) and ergosterol (e.g., *erg3Δ*, *erg5Δ*) biosynthesis. In 1981, Hadwiger et al. [144] detected chitosan within plant cytoplasm and nucleus within 15 min after application, which indicate that chitosan can efficiently penetrate the thicker cell wall (the reason for its detection) and potentially interfered with DNA transcription and translation. This study suggests that chitosan can easily penetrate microbial cells since plants have a thicker

Moreover, looking at the time factor (15 min), it is evident that chitosan can quickly interact with fungi and bacteria cellular DNA with subsequent inhibition of DNA transcription, as well as RNA and protein synthesis [140, 145, 146], leading to cell death. Chitosan triggered transcriptional responses when introduced to *S*. *cerevisiae* strain X2180-1A (MATa SUC2 mal gal2 CUP1). T-Profiler analysis showed cis-regulatory motifs apart from the environmental stress response correlated positively with expression in the chitosan-treated sample. Cin5p, Crz1p, and Rlm1p were the transcription factors associated with identified binding sites. Genes participating in cell wall organization, biogenesis, and signal transduction were also triggered in the treated sample compared to the control [134]. Some factors influencing the antimicrobial activity of chitosan is discussed above; however, Kong et al. [120] and Hosseinnejad and Jafari [147] published an excellent reviews on

**4. Ultradisperse humic sapropel suspension (UDHSS) nanoparticles** 

Sapropel is benthos found in fresh water, formed under anaerobic conditions from dead organic matter of anhydrobiotic microflora and microfauna. It is principally composed of nutrients (i.e., sugars, minerals, lipids, etc.) and organic compounds known as humic substances [148–151]. Sapropels and sapropel extracts showed antibacterial and antifungal properties in previous studies hence could used as an alternate and novel biocidal agent during grain storage. The antimicrobial properties of sapropels is attributed to the presence of humic substances [152–156]. Sapropel has become a popular raw material for therapeutic applications, production of sorbents, organic fertilizers, and food supplements [157]. UDHSS-NPs are organic NPs which exhibits potent biocidal activities due to the presence of humic substances [148]. Fulvic acids (FAs), humic acids (HAs), mumie, and humin are the principal constituents of humic substances (HSs) in sapropels [158–161], and are reportedly attribute to their biocidal properties. Many studies [152–155] have illustrated the inhibitory effects of sapropel on bacteria (*S*. *aureus*, *E*. *coli*, etc.) and yeasts (*Candida*, etc.). A micrograph of UDHSS-NPs is shown in **Figure 2** however,

In a series of tests performed by Barakova et al. [148], experiments 2 and 3 exhibited most significant fungicidal effects on *A*. *niger,* a species which poses a greater threat to grain/food industries due to the potent mycotoxins it produce. A report showed that hematite NPs (hematite-HA complexes) significantly

its characteristics were not included in the present study.

**144**
