Nowadays, the extract of seaweeds has drawn attention as a rich source of bioactive metabolites. Seaweeds are known for their biologically active compounds whose antibacterial and antifungal activities have been documented. This research aimed to study the profile of phenolic compounds using the HPLC method and determine biologically active compounds using the GC-MS method and the antifungal activity of Gracilariopsis persica against plant pathogenic fungi. G. persica was collected from its natural habitat in Suru of Bandar Abbas, Iran, dried, and extracted by methanol. The quantitative results on phenolic compounds using the HPLC method showed that the most abundant compounds in G. persica were rosmarinic acid (20.9 ± 0.41 mg/kg DW) and quercetin (11.21 ± 0.20 mg/kg DW), and the least abundant was cinnamic acid (1.4 ± 0.10 mg/kg DW). The GC-MS chromatography revealed 50 peaks in the methanolic extract of G. persica, implying 50 compounds. The most abundant components included cholest-5-en-3-ol (3 beta) (27.64%), palmitic acid (17.11%), heptadecane (7.71%), and palmitic acid methyl ester (6.66%). The antifungal activity of different concentrations of the extract was determined in vitro. The results as to the effect of the alga extract at the rates of 200, 400, 600, 800, and 1000 μL on the mycelial growth of four important plant pathogenic fungi, including Botrytis cinerea, Aspergillus niger, Penicillium expansum, and Pyricularia oryzae, revealed that the mycelial growth of all four fungi was lower at higher concentrations of the alga extract. However, the extract concentration of 1000 μL completely inhibited their mycelial growth. The antifungal activity of this alga may be related to the phenolic compounds, e.g., rosmarinic acid and quercetin, as well as compounds such as palmitic acid, oleic acid, and other components identified using the GC-MS method whose antifungal effects have already been confirmed.
The food industry's failure in planning and designing of and in implementing a Food Safety Management System and its foundation elements leads, in most instances, to compromised food safety and subsequent foodborne illness outbreaks. This phenomenon was noticed, worldwide, for all food processors, but with a much higher incidence in the medium- and small-sized food processing plants. Our study focuses on the importance of Food Safety Management System (FSMS), Critical Control Points Hazard Analysis (HACCP) and the Prerequisite Programs (PRPs) as the foundation of HACCP, in preventing foodborne outbreaks. For emphasis, we make use of the example of organizational food safety culture failures and the lack of managerial engagement which resulted in a multi-state listeriosis outbreak in USA. Moreover, we correlate this with microbiological criteria. Implementation of food safety management systems (ISO 22000:2018) along with incorporation of management tools such as HAZOP, FMEA, Ishikawa and Pareto have proved to be proactive in the maintenance of a positive food safety culture and prevention of cross-contamination and fraud.
Milk kefir fermentation has been used in households for generations. Consumption of milk kefir has been associated with various health benefits, presumably from the probiotics of yeast and bacteria that make up the kefir grains. In addition, many of the microbes are known to produce novel antimicrobial compounds that can be used for other applications. The microbes living inside kefir grains differ significantly depending on geographical location and production methods. In this study, we aimed to use metagenomic analysis of fermented milk by using three different kefir grains (kefir 1, kefir 2, and kefir 3) from different US sources. We analyzed the microbial compositions of the three milk fermentation samples. This study revealed that each sample contains unique and distinct groups of microbes, kefir 1 showed the least diversity, and kefir 3 showed the highest diversity. Kefir 3 is rich in Proteobacteria while kefir 2 is dominated by the Firmicutes. Using bacterial indicator growth analyses carried out by continuous readings from microplate-based bioreactor assays suggested that kefir 2 fermentation filtrate has higher antibacterial property. We have screened 30 purified cultures of kefir 2 sample and isolated two lactic acid bacteria strains with higher antibacterial activities; the two strains were identified as Leuconostoc mesenteroides 28-1 and Lentilactobacillus kefiri 25-2 by 16S genomic PCR with confirmed antibacterial activities of fermentation filtrate after growing under both aerobic and anaerobic conditions.
Siderophore-positive bacteria present in the rhizosphere and in bulk soil assist plants by either inhibiting phytopathogen proliferation or increasing plant growth. The bacterial diversity of the Shisham forest ecosystem in the Tarai region of the Western Himalayas was studied and used for siderophore production, taking into account the large-scale dieback and wilt-induced mortality in Dalbergia sissoo (common name: shisham) plantation forests and the importance of soil microbes in tree health. In addition, Pseudomonas, Burkholderia, and Streptomyces were prominent siderophore-positive bacteria in Shisham forests. Pseudomonas species are known for their remarkable siderophore-producing ability. Bacterial siderophores inhibit pathogen growth by rapidly lowering the number of ferric ions in the rhizosphere. The Pseudomonas monteilii strain MN759447 was isolated from a D. sissoo plantation forest at the Agroforestry Research Centre, Pantnagar, Uttarakhand (28°58'N 79°25'E/28.97°N 79.41°E). It produces a significant number of siderophore units (80.36% in total). A two-stage optimization of growth factors was attempted in the strain MN759447 for better siderophore recovery. In the first-stage single-factor experiment, among the five variables studied, only pH, NH4NO3 concentration, and Fe concentration affected siderophore synthesis. In the second stage, an optimization of pH, NH4NO3 concentration, and Fe concentration for improved growth and enhanced siderophore production was carried out using a Box-Behnken design with response surface methodology. By using LC-MS, two derivatives of pseudomonine, salicylic acid, and kynurenic acid were detected as siderophores in the purified XAD-2 methanol extract of the P. monteilii strain MN759447. In addition to siderophore production, the P. monteilii strain MN759447 also exhibited a broad range of antagonistic activity against Aspergillus calidoustus (65%), Fusarium oxysporum (41.66%), Talaromyces pinophilus (65%), and Talaromyces verruculosus (65.1%) that are linked to sissoo mortality. To our knowledge, this is the first report on siderophore-producing bacteria isolated, identified, and characterized from the D. sissoo Roxb. forest habitat. This strain can also be developed as a commercial product.
The current review aims to summarise the biodiversity and biosynthesis of novel secondary metabolites compounds, of the phylum Actinobacteria and the diverse range of secondary metabolites produced that vary depending on its ecological environments they inhabit. Actinobacteria creates a wide range of bioactive substances that can be of great value to public health and the pharmaceutical industry. The literature analysis process for this review was conducted using the VOSviewer software tool to visualise the bibliometric networks of the most relevant databases from the Scopus database in the period between 2010 and 22 March 2021. Screening and exploring the available literature relating to the extreme environments and ecosystems that Actinobacteria inhabit aims to identify new strains of this major microorganism class, producing unique novel bioactive compounds. The knowledge gained from these studies is intended to encourage scientists in the natural product discovery field to identify and characterise novel strains containing various bioactive gene clusters with potential clinical applications. It is evident that Actinobacteria adapted to survive in extreme environments represent an important source of a wide range of bioactive compounds. Actinobacteria have a large number of secondary metabolite biosynthetic gene clusters. They can synthesise thousands of subordinate metabolites with different biological actions such as anti-bacterial, anti-parasitic, anti-fungal, anti-virus, anti-cancer and growth-promoting compounds. These are highly significant economically due to their potential applications in the food, nutrition and health industries and thus support our communities' well-being.
Salinity is one of the most damaging abiotic stresses due to climate change impacts that affect the growth and yield of crops, especially in lowland rice fields and coastal areas. This research aimed to isolate potential halotolerant plant growth-promoting rhizobacteria from different rhizo-microbiome and use them as effective bioinoculants to improve rice growth under salinity stress conditions. Bioassay using rice seedlings was performed in a randomized block design consisting of 16 treatments (control and 15 bacterial isolates) with three replications. Results revealed that isolates S3, S5, and S6 gave higher shoot height, root length, and plant dry weight compared with control (without isolates). Based on molecular characteristics, isolates S3 and S5 were identified as Pseudomonas stutzeri and Klebsiella pneumonia. These isolates were able to promote rice growth under salinity stress conditions as halotolerant plant growth-promoting rhizobacteria. These three potent isolates were found to produce indole-3-acetic acid and nitrogenase.