Probiotic Isolates Research Articles

Probiotics screening from selected Nigerian prebiotics: Alternative starter culture sources for yoghurt production

The rise of functional foods has expanded food production, offering not just essential nutrition but also potential health and longevity benefits. This study aimed to identify probiotics from common Nigerian fermented foods as potential starter cultures for yogurt production. Ten local fermented food were screened for suitable starter culture(probiotics) for yogurt production, including fresh milk from cow (CM), sheep (SM), and goat (GM), as well as pap made from maize, millet, sorghum, cassava products (garri, fufu, and lafun), and Kunuzaki. Probiotic isolates with desired characteristics underwent tests for tolerance to acidic pH and bile conditions; antioxidative properties. Test yogurt was produced using Lactobacillus (LAB) isolates and physicochemical and organoleptic scores were determined for the yogurt samples. LAB species from CM, SM, and Lafun samples showed tolerance to both acidic pH (pH 3.0) and 0.5 percent bile. CM isolates exhibited strong antioxidant effects comparable to vitamin C. Yogurt samples had pH ranging from 4.77 to 5.45 and titratable acidity from 5.56 to 8.06. Sensory characteristics of the test yogurt did not significantly differ from commercial yogurt (p ≤ 0.05). Thus, probiotics (LAB) from common Nigerian fermented foods like CM, SM, and lafun could serve as cost-effective, nutrient-rich alternatives for yogurt starter cultures.

Isolation and Identification of Effective Probiotics on Drug-Resistant Acinetobacter baumannii Strains and Their Biofilms.

This study aimed to identify, assess, and isolate strong lactobacilli demonstrating broad antibacterial and anti-biofilm activity against drug-resistant strains of Acinetobacter baumannii. Additionally, the mechanism of inhibition of these organisms was to be determined. Over a 6-month period (from December 2021 to June 2022), 53 clinical A. baumannii strains were collected from clinical samples. Twenty probiotic strains were isolated from local dairy products. Antibacterial activity of Lactobacillus strains' cell-free supernatant (CFS) was identified using the agar well diffusion method and the microbroth dilution test. Anti-biofilm effect was performed by the microtiter plate assay. The MTT assay was also used to look into the probiotics' cytotoxic effects on the L929 fibroblast cell line. During the 6-month period, 53 clinical A. baumannii strains were obtained and identified. Out of 20 lactobacillus strains, the CFS of a lactobacillus strain (named L9) showed an inhibitory effect against all A. baumannii strains. Using the broth microdilution method, it was shown that the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CFS extracts of L9 strains against A. baumannii strains were both ¼ mg/mL. The result of the anti-biofilm showed that the selected probiotic could inhibit biofilm formation. The most common organic acid produced by all Lactobacillus strains, according to the HPLC method, was lactic acid, which was followed by acetic acid. The L929 fibroblast cell line was used in the cytotoxicity assay, which revealed that 100% of the cells in the L929 fibroblast cell line survived treatment with successive doses of CFSs for a full day. The probiotic strain isolated from local yogurt in this study showed potential anti-biofilm and antimicrobial properties against all drug-resistant Acinetobacter isolates. Given the increasing interest in probiotic microorganisms based on their high health benefits, further studies are recommended on the mechanisms of action between probiotics and A. baumannii strains to find new solutions for biological control and treatment of these infections without the use of antibiotics.

Characterization of Lactobacillus sp. isolated from deutoplasm for their probiotic potential

This study focuses on the isolation of probiotics from Deutoplasm and characterization of the probiotic potential of the isolates. Probiotics are live microorganisms that aid in maintaining our gut in healthy condition. In this study, Lactobacillus sp. were isolated from deutoplasm (boiled egg yolk) and identified based on the morphologies of their colonies and biochemical assays. Among 15 isolated LAB species, 5 were obtained after identification and purification. The five isolates (A, B, C, D, E) were further analyzed for their probiotic characteristics – acid tolerance, bile tolerance and auto-aggregation capacity. The antimicrobial activity was assessed and isolate B was found to be more resistant to the pathogens Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, and E. coli. Additionally, bile salt hydrolase activity and antibiotic resistance were examined for safety assessment. The isolates A and B were found to be highly resistant to the antibiotics – Vancomycin and Gentamicin. These five Lactobacillus isolates from boiled egg yolk are therefore intriguing candidates to be added to functional fermented foods as probiotics.

In vivo application of potent probiotics for enhancing potato growth and controlling Ralstonia solanacearum and Fusarium oxysporum infections

Plant probiotics are live microbial cells or cultures that support plant growth and control plant pathogens through different mechanisms. They have various effects on plants, including plant growth promotion through the production of indole acetic acid (IAA), biological control activity (BCA), and production of cellulase enzymes, thus inducing systemic resistance and increasing the availability of mineral elements. The present work aimed to study the potential of Achromobacter marplatensis and Bacillus velezensis as plant probiotics for the field cultivation of potatoes. In vitro studies have demonstrated the ability of selected probiotics to produce IAA and cellulase, as well as antimicrobial activity against two plant pathogens that infect Solanum tuberosum as Fusarium oxysporum and Ralstonia solanacearum under different conditions at a broad range of different temperatures and pH values. In vivo study of the effects of the probiotics A. marplatensis and B. velezensis on S. tuberosum plants grown in sandy clay loamy soil was detected after cultivation for 90 days. Probiotic isolates A. marplatensis and B. velezensis were able to tolerate ultraviolet radiation (UV) exposure for up to two hours, the dose response curve exhibited that the D10 values of A. marplatensis and B. velezensis were 28 and 16 respectively. In the case of loading both probiotics with broth, the shoot dry weight was increased significantly from 28 in the control to 50 g, shoot length increased from 24 to 45.7 cm, branches numbers increased from 40 to 70 branch, leaves number increased from 99 to 130 leaf, root dry weight increased from 9.3 to 12.9 g, root length increased from 24 to 35.7 cm, tuber weight increased from 15 to 37.0 g and tubers number increased from 9 to 24.4 tuber, the rot percentage was reduced to 0%. The addition of both probiotic isolates, either broth or wheat grains load separately has enhanced all the growth parameters; however, better results and increased production were in favor of adding probiotics with broth more than wheat. On the other hand, both probiotics showed a remarkable protective effect against potato pathogens separately and reduced the negative impact of the infection using them together.

Isolation, identification, and in vitro probiotic characterization of forty novel Bifidobacterium strains from neonatal feces in Erzurum province, Türkiye.

Neonatal feces are one of the most important sources for probiotic isolation. The purpose of this study was the isolation and identification of Bifidobacterium spp. from neonatal feces and the evaluation of in vitro probiotic properties of strains including safety tests. A total of 40 isolates were obtained from 14 healthy newborns' feces in Erzurum province, Türkiye. By their rep-PCR patterns and 16S rRNA gene sequences, isolates were identified as 26 Bifidobacterium breve and 14 Bifidobacterium longum. Fifteen of the isolates tolerated bile salts and showed high resistance to simulated gastric juice. Isolates exhibited varying rates of auto-aggregation and hydrophobicity. In addition, most of the isolates displayed antibacterial activity against Escherichia coli O157:H7, Staphylococcus aureus ATCC 29213, Salmonella Typhimurium RSHMB 95091, and Pseudomonas aeruginosa ATCC 9027. However, only one strain showed bile salt hydrolase activity and two strains showed the ability to produce H2O2. Bifidobacterium strains were generally sensitive to the tested antibiotics and lacked kanamycin, gentamicin, and streptomycin resistance genes, and hemolytic and DNAse activities. On the other hand, it was determined that five strains had various virulence genes including gelE, esp, efaAfs, hyl, and ace. Results of the present study suggested that B. longum BH28, B. breve BH4 and B. breve BH5 strains have the potential as probiotic candidates for further studies. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

PREPARATION OF HEALTH BENEFICIAL PROBIOTIC SOYA ICE -CREAM AND EVALUATION OF QUALITY ATTRIBUTES

Probiotic soya ice cream was prepared by using food grade bacteria Lactobacillus paracasei S1(MF443873) and Lactobacillus rhamnosus KC6 (MF443875). Bacteria have been encapsulated in milk and sodium alginate beads to improve their viability in soya ice -cream. Viable cell number of entrapped probiotic isolates was observed with calcium chloride concentration of 0.1M at pH 7.0, hardening time of 8h. Morphological characterization of microencapsulated beads was done by using SEM. Probiotic soy ice-cream was stored at -20oC for 30 days and was investigated for sensory qualities, microbial count and physicochemical characteristics. Microencapsulated probiotic ice-cream was found more stable during storage as compared to those containing free probiotic microorganisms. As far as physico-chemical characteristics of probiotic enriched soy ice-cream is concerned, though changes in quality attributes viz. pH, ascorbic acid, lactic acid, total soluble solid and antioxidant content during storage interval have been observed but these changes were statistically non- significant.

Detection of oxalyl-CoA decarboxylase (oxc) and formyl-CoA transferase (frc) genes in novel probiotic isolates capable of oxalate degradation in vitro

Oxalate degradation is one of lactic acid bacteria’s desirable activities. It is achieved by two enzymes, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). The current study aimed to screen 15 locally isolated lactic acid bacteria to select those with the highest oxalate degradation ability. It also aimed to amplify the genes involved in degradation. MRS broth supplemented with 20 mM sodium oxalate was used to culture the tested isolates for 72 h. This was followed by an enzymatic assay to detect remaining oxalate. All isolates showed oxalate degradation activity to variable degrees. Five isolates demonstrated high oxalate degradation, 78 to 88%. To investigate the oxalate-degradation potential of the selected isolates, they have been further tested for the presence of genes that encode for enzymes involved in oxalate catabolism, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). Three strains showed bands with the specific OXC and FRC forward and reverse primers designated as (SA-5, 9 and 37). Species-level identification revealed Loigolactobacillus bifermentans, Lacticaseibacillus paracasei, and Lactiplantibacillus plantarum. Preliminary results revealed that the tested probiotic strains harbored both oxc and frc whose products are putatively involved in oxalate catabolism. The probiotic potential of the selected strains was evaluated, and they showed high survival rates to both simulated gastric and intestinal fluids and variable degrees of antagonism against the tested Gram-positive and negative pathogens and were sensitive to clarithromycin but resistant to both metronidazole and ceftazidime. Finally, these strains could be exploited as an innovative approach to establish oxalate homeostasis in humans and prevent kidney stone formation.

Probiotic-loaded seed mucilage-based edible coatings for fresh pistachio fruit preservation: an experimental and modeling study

In this study, Lallemantia royleana mucilage (LRM) based edible coating containing 1.5 × 108 and 3 × 109 CFU/mL Lacticaseibacillus casei XN18 (Lbc1.5 and Lbc3) was designed to improve the quality and shelf-life of fresh pistachio. The fresh pistachios were coated with LRM + Lbc and their physicochemical, microbial, and sensory properties were evaluated after 1-, 5-, 15-, 25-, and 35-day storage at 4 °C. By the end of storage day, in comparison to control, the presence of probiotic isolate in the edible coating (particularly LRM + Lbc3) led to a marked decrease in fungal growth (3.1 vs. 5.8 Log CFU/g), weight loss (6.7 vs. 8.1%), and fat oxidation (0.19 vs. 0.98 meq O2/kg), and preserved total chlorophylls (8.1 vs. 5.85 mg/kg) and phenols (31.5 vs. 20.32 mg GAE/100 g), and antioxidant activity (38.95 vs. 15.18%) of samples during storage period. Furthermore, LRM + Lbc3-coated samples had a probiotic number above the recommended level (6.85–9.29 log CFU/g) throughout storage. The pistachios coated with probiotic-enriched edible coatings were greatly accepted by panelists. In the next section, Gaussian Process Regression (GPR) was used for predicting some parameters including: weight loss, TSS, Fat content, PV, Soluble carbohydrate content, Viability, Total phenolic compounds, Antioxidant activity, Mold and yeast, Total chlorophylls, Total carotenoids, Color, Odor and Overall acceptance. The results indicated that, there is a good agreement between the actual and predicted data by GPR model and it can be used for similar situation to decrease the cost of laboratory tests and increase the respond of analysis.

Probiotics and their Beneficial Health Effects.

Probiotics are living microorganisms that are present in cultured milk and fermented food. Fermented foods are a rich source for the isolation of probiotics. They are known as good bacteria. They have various beneficial effects on human health including antihypertensive effects, antihypercholesterolemic effects, prevention of bowel disease, and improving the immune system. Microorganisms including bacteria, yeast, and mold are used as probiotics but the major microorganisms that are used as probiotics are bacteria from the genus Lactobacillus, Lactococcus, Streptococcus, and Bifidobacterium. Probiotics are beneficial in the prevention of harmful effects. Recently, the use of probiotics for the treatment of various oral and skin diseases has also gained significant attention. Clinical studies indicate that the usage of probiotics can alter gut microbiota composition and provoke immune modulation in a host. Due to their various health benefits, probiotics are attaining more interest as a substitute for antibiotics or anti-inflammatory drugs leading to the growth of the probiotic market.

Isolation of Lactiplantibacillus plantarum producing Extracellular Lipase from Dairy Products and Optimization of the Enzyme Production

Recently, microbial lipases isolated from probiotic bacteria have attracted the attention of many scientists because they have significantly beneficial properties for human health. As a highly nutritious substrate, dairy products possess great potential for probiotic bacteria isolation. The main purpose of this study was to isolate probiotic bacteria in order to search for lipase producing bacteria. The bacteria were isolated from dairy products and purified by repeated sub-culturing on MRS medium at 37°C. The isolates were subjected to primary and secondary screening via fluorometric and colorimetric methods respectively. The isolates showing orange fluorescence under UV light at 350 nm around their colonies were selected for the colorimetric method. In this method, lipase activity was investigated by p-nitrophenyl palmitate. Probiotic characterizations of lipase-producing isolates were performed by acid resistance test, cell surface hydrophobicity assay, auto-aggregation and co-aggregation. The optimization of lipase production was performed by Central Composite Design (CCD). In the present study, 92 isolates were recovered from 71 samples. The results showed that 41 isolates were positive for fluorometric assay. According to the amount of enzyme production, seven strains were selected for probiotic characterizations. Finally, a potential probiotic strain of genus Lactobacillus showed the highest enzyme activity with 3.4 U.ml-1 compared to other isolates. This strain showed 100% similarity to Lactiplantibacillus plantarum. This research indicated that the lipase of Lactiplantibacillus plantarum can be used as a promising enzyme in the food and medicine industries.

Improvement of the probiotic cultures method isolation from freshly extracted honey

The study of probiotic microorganisms isolated from bee honey has recently become widespread in the world and is of great interest both for the prevention and treatment of bee diseases, and as a source of probiotics for the design of drugs useful for humans and animals. However, no studies have been conducted to study the duration of probiotic bacteria storage in honey after it has been pumped out of the combs. Three types of honey (acacia, sunflower and multi-herb) were studied to determine the intensity of growth of probiotic bacteria on the first, second, third and fourth day after pumping, as well as after storing honey for 6 months in sealed honeycombs. Honey samples were prepared in dilution with MRS broth, sown on a solid nutrient medium, the results were recorded after 48 hours by counting colonies of different species. Selected cultures were characterized by cultural, morphological and biochemical properties. It was established that bacteria are released during the first 3 days after honey is pumped out, on the other hand, on the 4th day of storage, there is no growth of probiotic bacteria, which indicates the impossibility of obtaining them. The prospect of using honey of any different botanical origin for the isolation of probiotic bacteria has been proven. A study of honey stored in sealed honeycombs for 6 months confirmed the hypothesis that normal flora bacteria with probiotic properties are stored in honeycombs for a long time and can be used for their isolation, identification and further use. In the course of the study, the method of isolating bacteria of the normal flora of the intestine of bees, namely Lactobacillus plantarum, Bifidobacterium bifidum and Enterococcus faecium from freshly extracted honey, was improved and developed. Key words: normal flora, probiotic bacteria, freshly squeezed honey, Lactobacillus plantarum, Bifidobacterium bifidum, Enterococcus faecium.

Effect of Adding Probiotic Yeast and Fermentation Time on Probiotic Tempeh Characteristics

Tempeh is one of the foods made from soybean seeds or other ingredients that are processed through fermentation. Tempeh currently circulating in the community does not contain probiotic yeast, the addition of probiotic yeast is intended to provide probiotic properties to tempeh. From previous studies, yeast isolates from radishes and tomatoes have been identified as potential probiotic yeasts. This study aimed to determine the effect of adding the type of probiotic yeast isolate and fermentation time on the number of fungi, the number of yeasts, pH, antioxidant activity, and the level of preference by panelists for the resulting probiotic tempeh. This study used a completely randomized design with a factorial pattern. The first factor was the type of probiotic inoculum (Saccharomyces boulardii, yeast isolate LBK K, yeast isolate TMT 2), and the second factor was incubation time (0 hours, 24 hours, and 48 hours). The analysis included the number of fungus and yeast (plate count agar), antioxidant activity (radical scavenging activity (%), and preference level for probiotic tempeh. The data obtained were analyzed for variance (ANOVA) at a 95% confidence level. If there was a significant difference between each treatment was continued with Duncan's multiple range test (DMRT). The results showed that adding probiotic yeast type and a long incubation time affected the microbiological properties, antioxidant activity, and panelist preference. The most preferred tempeh was tempeh with the addition of LBK K isolate with an incubation time of 48 hours with a pH of 5.46, the total number of fungi was 6.62 log CFU/g, the total amount of yeast was 8,63 log CFU/g, the antioxidant activity was 18.58% RSA. Tempeh, with the addition of LBK K yeast isolate, has the potential as a probiotic food.

Isolation, Identification, and Pathogenicity of Potential Probiotics Isolated from Intestinal Coconut Crab (Birgus latro Linnaeus, 1767)

Abstract The supply of coconut crabs (Birgus latro Linnaeus, 1767) has been sourced from capture in the wild. Development efforts in aquaculture have succeeded in producing eggs. However, further development with larval maintenance failed because it was constrained by a low survival rate. This study aimed to identify the potential probiotic bacteria in coconut crabs. Coconut crab samples were collected from Moor Island, South Patani District, Central Halmahera Regency, North Maluku Province, Indonesia. The intestines of coconut crabs were taken as much as 1 g, then ground on a porcelain dish and added to Tri-Salt. The scouring liquid was taken in 0.1 ml and spread on a petri dish containing Nutrient Agar. The isolated used were marked with BL1, BL2, BL3, BL4, and BL5. Molecular identification was performed with sequencing and then analyzed using the Basic Local Alignment Search Tool (BLAST). The selection of isolates from the gastrointestinal tract of coconut crabs showed that the bacteria obtained were Enterobacter tabaci (BL1), Enterobacter hormaechei (BL2), Bacillus horneckiae (BL3), Pseudomonas stutzeri (BL4), and Acinetobacter variabilis (BL5). Further testing revealed that the bacteria A. variabilis (BL5) is a probiotic isolate in coconut crabs. Highlight Research The intestinal bacteria from coconut crabs identified were E. tabaci, E. hormaechei, B. horneckiae, P. stutzeri, and A. variabilis. The E. tabaci strain BL1, E. hormaechei strain BL2, B. Horneckiae strain BL3, and P. stutzeri strain BL4 are pathogenic bacteria. The A. variabilis strain BL5 is potential probiotics bacteria. The A. variabilis strain BL5 showed a better survival rate than other isolates.

Assessment of Antibacterial, Cytotoxicity and Wound Healing Influence of Copper Nanoparticles Synthesized using Probiotic Bacteria

The present article targeted to biosynthesis and description of copper oxide nanoparticles (CuO NPs) using probiotic isolate and assessment the antibacterial, cytotoxicity of these NPs and its effect on wound heals. The CuO NPs are biosynthesized using probiotic isolate identified as Bacillus cereus. These CuO NPs are characterized using UV, FT-IR, Zeta and TEM. The antibacterial efficiency is assayed by agar plate diffusion protocol. Results assured that the CuO NPs can prevent Staphylococcus aureus jointly Escherichia coli growth. MTT procedure exercised to detect cytotoxicity and wound healing effects. The results revealed that CuO NPs can use as antibacterial agent with non-significant effects on host cells and wound healing.

Isolation, Identification and Study of Antimicrobial Property of Potential Probiotic Bacteria from Dairy Products of Lucknow City

Probiotics are the nonpathogenic and alive bacteria that confer good effects on the host. The important property of probiotics is direct antimicrobial effects, stimulation of immunity, competing for adhesion site, completion for nutrients and improvement in digestion. Since ancient times different fermented dairy products have been used as the main source of probiotic bacteria. The main objective of this study was to isolate, identify and characterize lactic acid bacterial strains from different fermented dairy products including yoghurt, cheese, buttermilk and curd. To determine the potentials of probiotics different tests like bile tolerance, salt tolerance, acid tolerance and arginine hydrolysis were performed. In the present study it was observed that all the probiotic isolates were able to grow at low pH (2-6) and they were tolerant against NaCl (2%, 4%, 6%) and bile salt concentration (0.2%, 0.4%, 0.6%). The probiotic isolates were shown to be arginine-positive as on a white background they displayed a bright orange colour. The growths of probiotic cultures were observed at different temperature i.e 10 °C and 45°C and were able to ferment different types of carbohydrates such as glucose, sucrose and lactose. The probiotic isolates showed good antimicrobial activities against the four test organisms. The present study showed that the probiotic strains isolated from different fermented dairy products carry antimicrobial property and can be used to control gut microbiota. The observation of the present study showed that dairy products can be used as a good source of potentially probiotic bacteria.

ISOLATION AND IDENTIFICATION OF INDIGENOUS PROBIOTICS FROM DAIRY PRODUCTS AND HUMAN BREAST MILK

Probiotics are live microbes that beneficially affect the human and many studies have proved their promising role as safe and natural therapeutics. The isolation of probiotics from indigenous sources may develop a new way to improved probiotic strains with precious medical relevance for human benefits. Hence the aim of the present study is to isolate probiotics from locally available various dairy products (Viz. raw milk of cow and buffalo and traditional homemade curds) and human breast milk and to identify them upto species level. A total of about 80 samples from human breast milk (n=30) and dairy products (n=50) were collected aseptically and screened for the probiotic microflora using standard microbiological methods. The colonies suspected for probiotics were picked up for morphological and biochemical identification which were further confirmed by molecular methods and application of bioinformatics. The preliminary results showed several different microflora viz. Streptococcus, Staphylococcus, Lactobacillus, Diplococcus, etc. About twelve (12) isolates were further confirmed to be of different species belonging to the Genus Lactobacillus. Therefore dairy products and human breast milk are considered as suitable natural sources for probiotic microorganisms especially Lactobacillus spp., which are reported to show beneficial effects in humans.

Isolation of Pediococcus pentosaceus to compete Vibrio harveyi in the shrimp Litopenaeus vannamei hatchery

Abstract. Haliman RW, Kurnia MD, Iman MN, Kusuma SA, Halalludin B, Rizkiantino R, Sari PP, Rahayu M, Fitriana RN, Panjaitan BV, Jacinda AK, Laiman H. 2023. Isolation of Pediococcus pentosaceus to compete Vibrio harveyi in the shrimp Litopenaeus vannamei hatchery. Biodiversitas 24: 4514-4520. Shrimp is an aquaculture commodity with high economic value, and is widely cultured in Asia and South America. Among diseases in the shrimp hatchery, vibriosis is considered as the main problem, with emphasize on Vibrio harveyi infection. Probiotics are life microbes with defense mechanism against pathogens, and have been used in aquaculture as an alternative strategy in disease management through application into the water or through the feed. In order to renew the current probiotics available, exploration of probiotic candidate isolates with ability to compete with the luminous bacteria has been done in mangrove area of Merak Belantung, Kalianda, Lampung Province, Indonesia, and also from shrimp intestine, raised in the tank of research facility. Nine bacteria isolates were obtained from this exploration, and based on the references, 4 isolates had the potential to compete Vibrio harveyi. Based on the 16S rRNA sequencing result, those 4 isolates were Bacillus cereus, B. aryabhattai, Weisella paramesenteroides, and Pediococcus pentosaceus. Further analysis of in vitro test using agar-well diffusion inhibition method and in vivo test showed that among those 4 isolates, only P. pentosaceus had strong antibacterial activity against V. harveyi and could be used as probiotic in shrimp rearing with optimal dose at 5-10 µL L-1.

Halotolerant Plant Probiotic Bacterial Isolates of Mangrove Soils of Chidambaram and Thanjavur, India

Halotolerant plant growth-promoting rhizobacteria (HTPGPR) are beneficial microbes that can be exploited to mitigate the negative effects of soil salinity on crops. In the current investigation, eight saline soil samples collected from 2 mangrove ecosystems of Tamil Nadu (Chidambaram and Thanjavur) during December 2022 were used to isolate saline tolerant bacterial cultures at the Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. Using 5 different bacterial growth media, 48 rhizobacterial isolates (ST1 to ST48) were obtained. Salt tolerance ability (0, 5, 10, 15 and 20% NaCl) of these 48 isolates under in vitro conditions indicated their potential to tolerate up to 10% NaCl (1.71 M). None of the isolates could grow at 20% NaCl (3.42M). Bacterial isolates such as ST11, ST13, ST18, ST20 and ST27 showed minimum growth at 15%NaCl (2.57M). 33 isolates which could grow well at higher salt concentrations were selected. Among 33 isolates, 18 isolates with higher concentration of intracellular sodium content (ST1, ST2, ST3, ST7, ST8, ST9, ST11, ST12, ST13, ST17, ST18, ST20, ST27, ST30, ST32, ST34, ST39, and ST40) were selected and characterized qualitatively for their ability to mineralize phosphate, potassium, and zinc, and to produce HCN. Potential of these18 bacterial isolates to tolerate other abiotic stress factors such as pH and temperature was also studied. Among 18 isolates, the isolates ST7, ST17, and ST30 were found to be multimineral solubilizers. Bacterial isolate ST17 was found to prefer alkaline (pH 9.0) and mesophilic temperature (35ºC) for its growth at both saline (5% NaCl) and non saline condition.

Evaluation of dietary single probiotic isolates and probiotic multistrain consortia in growth performance, gut histology, gut microbiota, immune regulation, and infection resistance of Nile tilapia, Oreochromis niloticus, shows superior monostrain performance.

The probiotic potential of a designed bacterial consortia isolated from a competitive exclusion culture originally obtained from the intestinal contents of tilapia juveniles were evaluated on Nile tilapia alevins. The growth performance, intestinal histology, microbiota effects, resistance to Streptococcus agalactiae challenge, and immune response were assessed. In addition, the following treatments were included in a commercial feed: A12+M4+M10 (Lactococcus lactis A12, Priestia megaterium M4, and Priestia sp. M10), M4+M10 (P. megaterium M4, and Priestia sp. M10) and the single bacteria as controls; A12 (L. lactis A12), M4 (P. megaterium M4), M10 (Priestia sp. M10), also a commercial feed without any probiotic addition was included as a control. The results showed that all probiotic treatments improved the growth performance, intestinal histology, and resistance during experimental infection with S. agalactiae in comparison to the control fish. Also, the administration of probiotics resulted in the modulation of genes associated with the innate and adaptive immune systems that were non-dependent on microbial colonization. Surprisingly, L. lactis A12 alone induced benefits in fish compared to the microbial consortia, showing the highest increase in growth rate, survival during experimental infection with S. agalactiae, increased intestinal fold length, and the number of differentially expressed genes. Lastly, we conclude that a competitive exclusion culture is a reliable source of probiotics, and monostrain L. lactis A12 has comparable or even greater probiotic potential than the bacterial consortia.

Evaluation of Biofloc-Based Probiotic Isolates on Growth Performance and Physiological Responses in Litopenaeus vannamei

A comparison of the growth performance of Penaeus vannamei was ascertained by supplementing the potential probiotics isolated from a biofloc system incorporated through feed. Post-larvae shrimp (0.045 ± 0.005 g) were stocked at a density of 500/m3 in FRP tanks (500 L) in triplicates for a period of 60 days. A total of 40 bacterial strains were isolated from previous biofloc culture trials and tested for their antimicrobial activity against the pathogen Vibrio parahaemolyticus. Among these, Bacillus megaterium, Exiguobacterium profundum, Pseudomonas balearica, and Pseudomonas stutzeri showed higher antimicrobial activity. The treatment groups included clear water with no probiotics (CW), clear water + isolated probiotic (CW + IP), biofloc alone (BFT), and biofloc + isolated probiotic (BFT + IP), in triplicates. Distillery spent wash was used as a carbon source for biofloc development and maintenance. A probiotic concentration of 1 × 109 cfu/g was supplemented throughout the trial. The recorded water quality parameters (pH, alkalinity, calcium, and magnesium) were observed to be significant among the experimental groups (p ≤ 0.05). The highest weight gain (2.43 g), SGR, PER, and lower FCR values were recorded in BFT + IP. The lowest values of total Vibrio were found in BFT. The histology analysis revealed that there was a mild increase in the B and R cell vacuoles in the hepatopancreas of CW and BFT + IP, whereas mild degeneration was found in the intestine of CW and CW + IP. Microbiome analysis of the shrimp gut revealed that Proteobacteria was the most abundant phylum in all experimental groups. P. balearica, K. pneumoniae, P. stutzeri, and E. profundum were present in the gut of C, whereas P. balearica, K. pneumonia, and P. stutzeri were present in the gut of CW + IP and BFT + IP. The results proved that the probiotics isolated from biofloc colonized in shrimp gut could play a promising role in aquaculture.