Many strategies have been used to increase the number of bacterial cells that can be grown from environmental samples but cultivation efficiency remains a challenge for microbial ecologists. The difficulty of cultivating a fraction of bacteria in environmental samples can be classified into two non-exclusive categories. Bacterial taxa with no cultivated representatives for which appropriate laboratory conditions necessary for growth are yet to be identified. The other class is cells in a non-dividing state (also known as dormant or viable but not culturable cells) that require the removal or addition of certain factors to re-initiate growth. A number of strategies, from simple to high throughput techniques, are reviewed that have been used to increase the cultivation efficiency of environmental samples. Some of the underlying mechanisms that contribute to the success of these cultivation strategies are described. Overall this review emphasizes the need of researchers to first understand the factors that are hindering cultivation to identify the best strategies to improve cultivation efficiency.
Functional variation of Rpf, a growth factor found exclusively in Actinobacteria, is differentiated by its source and amino acid sequences. Only purified Rpf proteins from three species have been studied so far. To seek new Rpfs for use in future studies to understand their role in Actinobacteria, the objective of this study was to identify rpf gene homologs in Tomitella biformata AHU 1821T, a novel Actinobacteria isolated from permafrost ice wedge. Amplification using degenerate primers targeting the essential Rpf domain led to the discovery of a new rpf gene in T. biformata. Gene structure and the deduced Rpf domain amino acid sequence indicated that this rpf gene was not identical to previously studied Rpf. Phylogenetic analysis placed T. biformata Rpf in a monophyletic branch in the RpfB subfamily. The deduced amino acid sequence was 44.9% identical to RpfB in Mycobacterium tuberculosis, the closest functionally tested Rpf. The gene was cloned and expressed in Escherichia coli; the recombinant Rpf protein (rRpf) promoted the growth of dividing cells and resuscitated non-dividing cells of T. biformata. Compared to other studies, this Rpf was required at higher concentrations to promote its growth and to resuscitate itself from a non-dividing state. The resuscitation function was likely due to the highly conserved Rpf domain. This study provides evidence that a genetically unique but functional Rpf can be found in novel members of Actinobacteria and can lead to a better understanding of bacterial cytokines in this phylum.
Southeast Maluku Regency, Maluku. Freshlycollected specimen of sponges and part of coastal plants including barks, leaves, fruits, and twigs were immediately transported to the laboratory. A total of 32 samples were washed with water to remove ABSTRACT Objective: The objective of this study was to investigate the antibacterial activity of coastal plants and marine sponges extracts against fish bacterial pathogens. Methods: Samples were extracted by maceration and the extracts were examined for their antibacterial activities against Streptococcus sp. BJ0509, Staphylococcus aureus ATCC 6538, Aeromonas hydrophila BA03 and Vibrio parahaemolyticus 29S by means of paper disc diffusion method. Active extracts were partitioned and purified by column chromatography. The purified substance was tested for minimum inhibitory concentration (MIC) against seven bacterial fish pathogens namely Streptococcus sp., Vibrio parahaemolyticus, V. alginolyticus, V. harveyi, Photobacterium damselae, Aeromonas hydrophila and A. dhakensis. Results: The highest antibacterial activity against all bacteria used in the assay was demonstrated by OKA 6, a bark extract sample of a coastal plant, Diospyros maritima. It showed a diameter of inhibition zones against Streptococcus sp. BJ0509, S. aureus ATCC 6538, A. hydrophila BA03 and V. parahaemolyticus 29S of 19, 33, 18, and 18 mm, respectively. The column chromatography fraction of OKA 6 inhibited the growth of S. aureus ATCC 6538 with MIC of 3.125 µg/mL. The MIC of this fraction against seven bacterial fish pathogens ranged < 0.098 to 3.125 µg/mL. The antibacterial activity of partially purified substance obtained from column chromatography fractionation of OKA 6 was higher than those of oxytetracycline and kanamycin. Conclusions: This result indicates that antibacterial activity of the partially purified substance is potentially higher than those of the commercial antibiotics tested. It further indicates that OKA 6 extract from D. maritima can serve as a promising resource for the development of therapeutic agents against bacterial infections in aquaculture.
Resuscitation-promoting factor (Rpf) is a protein that has been found in a number of different Actinobacteria species and has been shown to promote the growth of active cells and resuscitate dormant (non-dividing) cells. We previously reported the biological activity of an Rpf protein in Tomitella biformata AHU 1821T, an Actinobacteria isolated from a permafrost ice wedge. This protein is excreted outside the cell; however, few studies have investigated its contribution in environmental samples to the growth or resuscitation of bacteria other than the original host. Therefore, the aim of the present study was to determine whether Rpf from T. biformata impacted the cultivation of other bacteria from the permafrost ice wedge from which it was originally isolated. All experiments used recombinant Rpf proteins produced using a Rhodococcus erythropolis expression system. Dilutions of melted surface sterilized ice wedge samples mixed with different doses of the purified recombinant Rpf (rRpf) protein indicated that the highest concentration tested, 1250 pM, had a significantly (p <0.05) higher number of CFUs on agar plates after 8 d, approximately 14-fold higher than that on control plates without rRpf. 16S rRNA gene sequences revealed that all the colonies on plates were mainly related to Brevibacterium antiquum strain VKM Ac-2118 (AY243344), with 98–99% sequence identity. This species is also a member of the phylum Actinobacteria and was originally isolated from Siberian permafrost sediments. The results of the present study demonstrated that rRpf not only promoted the growth of T. biformata from which it was isolated, but also enhanced colony formation by another Actinobacteria in an environmental sample.
This study was conducted to develop Chaguro, a low-cost supplementary food made of chayote (Sechium edule (Jacq.) Swartz) and tuna fish (Thunnus sp.), for diabetes and dyslipidemia diet therapy. In order to find a formula with effective hypoglycaemic and antidyslipidemic properties, dried tuna and chayote were mixed at different ratios: F1 (75% tuna, 25% chayote), F2 (50% tuna, 50% chayote), and F3 (25% tuna, 75% chayote). Thirty male Sprague Dawley rats were assigned into healthy control group or groups induced with streptozotocin-nicotinamide and a high-fat diet. Chaguro was administered 2.7 g/ kgBW/ day using a gavage for 28 days. The administration of all Chaguro formulas improved blood markers compared to the negative control group (p < 0.001). Chaguro F2 lowered fasting blood glucose (97.07±1.18 vs 266.31±5.31), total cholesterol (113.59±2.22 vs 208.78±4.31), triglycerides (89.93±2.51 vs 142.35±2.83), LDL-c (33.87±1.87 vs 87.85±3.34) and increased HDL-c (69,08±1,85 vs 23,91±1,64) level the most compared to the negative control group (p < 0.001). Streptozotocin-induced weight loss was also prevented in all diabetic rats fed with Chaguro, with the bodyweight being similar to that of healthy controls at the end of the intervention (p < 0.001). This study found that Chaguro may be a potential food product to help lower blood glucose and improve lipid profile in diabetes and dyslipidemia.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.