High Viable Cell Counts Research Articles

Regulation of Cultivation Temperature on Biomass and Activity of Bifidobacterium breve B2798

Bifidobacterium is among the dominant flora in the healthy intestine of the human body. It has many probiotic effects such as lowering cholesterol, inhibiting tumors, and regulating immunity. However, fluctuations in culture conditions during cultivation will lead to a decrease in the number of active bacteria. Therefore, more precise control of culture conditions is required to reduce the activity damage caused by environmental fluctuations. Based on this, this study utilized a fully automatic intelligent fermentation tank to develop a cultivation technique suitable for improving the activity and biomass of Bifidobacterium breve B2798. The results show that, under a cultivation temperature of 38.0 °C, the highest viable cell count, which is (2.56 ± 0.04) × 1010 CFU/mL, can be achieved in the culture medium, with the conclusion that the fermentation endpoint should be controlled at the end period of bacteria logarithmic growth when there is the highest viable cell count and bacterial activity in the culture medium. This study has elucidated the influences of different temperatures on the biomass, viable cell count, and activity of Bifidobacterium breve B2798, providing basic data for the later development of industrialized processing techniques for this bacteria strain.

Cereus jamacaru DC. (mandacaru) fruit as a source of lactic acid bacteria with in vitro probiotic-related characteristics and its protective effects on Pediococcus pentosaceus during lyophilization and refrigeration storage

This study isolated and identified autochthonous lactic acid bacteria (LAB) from mandacaru fruit and evaluated their potential probiotic and technological aptitudes in vitro, as well as the protective effects of freeze-dried mandacaru fruit on the most promising LAB isolate during lyophilization and refrigeration storage. Initially, 212 colonies were isolated from mandacaru fruit, and 34 were preliminarily identified as LAB. Thirteen isolates identified by 16S-rRNA sequencing as Pediococcus pentosaceus were negative for DNase, gelatinase, hemolytic, and biogenic amine production. The selected isolates showed proteolytic activity, diacetyl and exopolysaccharide production, and good tolerance to different NaCl concentrations while having low cellular hydrophobicity and antagonistic activity against pathogens. The survival of isolates sharply decreased after 3 h of exposure to pH 2 and had a good tolerance to 1 % bile salt. A principal component analysis selected P. pentosaceus 57 as the most promising isolate based on the examined technological and probiotic-related physiological properties. This isolate was lyophilized with mandacaru fruit and stored under refrigeration for 90 days. P. pentosaceus 57 lyophilized with mandacaru fruit had high viable cell counts (9.69 ± 0.03 log CFU/mL) and >50 % of physiologically active cells at 90 days of refrigeration storage. The results indicate that mandacaru fruit is a source of P. pentosaceus with aptitudes to be explored as potential probiotic and technological characteristics of interest for the food industry, besides being a good candidate for use in lyophilization processes and refrigeration storage of LAB due to its cryoprotective effects.

Development of a probiotic low-fat set yogurt containing concentrated sweet pepper extract.

Yogurt contains various health-promoting components such as beneficial bacteria and bioactive peptides. However, plain yogurt is regarded as a poor source of phenolic compounds, vitamin C, and other substances that give a high antioxidant property to the product. Since the objective of this study was to evaluate the impact of the addition of different concentrated sweet pepper extracts (CSPE) to the yogurt milk formulation on some quality parameters of the probiotic set yogurt during 21 days of cold storage. For the production of probiotic yogurt samples, Lactobacillus acidophilus LA-5 was used as probiotic bacteria. The functional set yogurts containing 5% of yellow, orange, or red CSPE were prepared and compared with probiotic control yogurt (without CSPE). With incorporation of CSPE, a functional yogurt with high viable cell counts of probiotics (>108 cfu/g), appropriate acceptability (acceptance scores more than 7, i.e., good acceptability), and textural quality produced. Fortified CSPE yogurt displayed large flakes with irregular surface and more compact texture as compared to the control sample. Based on the results of the study, the yogurt sample having orange CSPE was selected as the best functional product. After 21 days of storage, orange CSPE had the highest hardness (173.33 mg), consistency (1183.33 mg/s), and probiotic counts (8.3 log cfu/g) than other yogurt samples.

The influence of nutrients on biofilm formation of an ST87 strain of Listeria monocytogenes

Biofilm development by pathogenic organisms plays a pivotal role in certain foodborne illnesses. Listeria monocytogenes, specifically the sequence type 87 (ST87), has been widely identified in China. This study aimed to monitor the dynamic process of biofilm formation by a food-isolated L. monocytogenes ST87 strain under diverse nutritional conditions. Results showed that this strain can consistently exhibit high viable cell counts in both nutrient-rich and nutrient-limited conditions. By utilizing cell counting, we discovered the ability of L. monocytogenes ST87 to form biofilms in various nutritional environments, including beef juice and vegetable juice, maintaining levels above 2 Log10 CFU/cm2. Notably, biofilm formation was expedited under nutrient-limited conditions, with cell counts under nutrient-limited vegetable juice presenting significantly higher than that under the nutrient-rich one. The analysis of the composition of extracellular polymeric substances (EPS) showed a consistent pattern between viable cell count and extracellular protein variation within the biofilms. Moreover, an evaluation of nutritional components (protein, fat, total sugar, ash, and pH) in the culture medium unveiled a positive correlation between extracellular substances and pH, but a negative correlation was identified with other nutritional components.

An In Vitro Study of the Impacts of Sweet Potato Chips with Potentially Probiotic Levilactobacillus brevis and Lactiplantibacillus plantarum on Human Intestinal Microbiota : Impacts of potato chips with probiotics on intestinal microbiota.

This study formulated sweet potato chips with powdered potentially probiotic Levilactobacillus brevis (SPLB) and Lactiplantibacillus plantarum (SPLP) and evaluated their impacts on human intestinal microbiota during 48h of in vitro colonic fermentation. L. brevis and L. plantarum kept high viable cell counts (> 6 log CFU/g) on sweet potato chips after freeze-drying and during 60days of storage. SPLB and SPLP had satisfactory quality parameters during 60days of storage. SPLB and SPLP increased the relative abundance of Lactobacillus ssp./Enterococcus spp. (3.84-10.22%) and Bifidobacterium spp. (3.25-12.45%) and decreased the relative abundance of Bacteroides spp./Prevotella spp. (8.56-2.16%), Clostridium histolyticum (8.23-2.33%), and Eubacterium rectale/Clostridium coccoides (8.07-1.33%) during 48h of in vitro colonic fermentation. SPLB and SPLP achieved high positive prebiotic indexes (> 8.24), decreased pH values and sugar contents, and increased lactic acid and short-chain fatty acid production, proving selective stimulatory effects on beneficial bacterial groups forming the intestinal microbiota. The results showed that SPLB and SPLP have good stability and high viable cell counts of L. brevis and L. plantarum when stored under room temperature and caused positive impacts on human intestinal microbiota, making them potentially probiotic non-dairy snack options.

Optimization of sugarcane juice as a culture medium for scale up of Lactobacillus plantarum TISTR 2083 production

Lactobacillus plantarum TISTR 2083 is one of the industrially relevant lactic acid bacteria vastly used as a probiotic. The culture of L. plantarum TISTR 2083 in sugarcane juice was studied to optimize the culture medium and growth conditions for the highest viable cell production at a low cost. The effect of sugar content (5 - 20°Bx), amount of seed culture (1 - 10%), different nitrogen sources (ammonium sulfate, diammonium phosphate, yeast extract and peptone) with different concentrations (0 – 1.5%), and different agitation speeds (0 – 150 rpm) were investigated in the sugarcane juice growth media for higher cell growth of L. plantarum TISTR 2083. The concentration of sugarcane juice was optimized with 5, 10, 15, and 20°Bx. The highest cell viability was found in the 20°Bx sugarcane juice as 8.90-9.24 log CFU/mL. Moreover, seedlings with a 5% (v/v) seed culture maximized the viable cell (9.07 log CFU/mL) than 1, 3, 7, and 10% seed cultures, respectively. Among different nitrogen sources, high cell viability was obtained using 1.5% yeast extract (8.76-9.11 log CFU/mL). With all other optimized parameters, the agitation speed of 100 rpm resulted in a higher viable cell count. Optimized sugarcane juice can be used as a low-cost medium and a simple bottle fermenter for the scale-up of L. plantarum.

Enhanced production rate of probiotic Enterococcus faecium A028 by repeated batch solid-state fermentation and its survival under hot air drying with cell-protective agents

Probiotic viability is an important aspect of animal feed additives. Enterococcus faecium A028, a potential probiotic, was isolated from the intestinal digestion track of chicken. Production rate of E. faecium A028 probiotic inoculum with high total viable cell count (TVC) was enhanced using repeated batch solid-state fermentation (RB-SSF). The probiotic strain grew well in soybean meal (SBM) with average TVC of over 9 LogCFU/g in all RB-SSF experiments. Average specific growth rate of E. faecium A028 in fermented SBM (FSBM) was 50% repeated batch ratio (RB ratio) for 0.37 h−1, and higher than the batch process (0.33 h−1). Probiotic inoculum production rate was enhanced by increasing the RB ratio. Highest total TVC production rate was 128.15 LogCFU/h at 90% RB ratio, while average TVC was 9.09 LogCFU/g. Total production of FSBM at 90% RB ratio was 1.6 times higher than batch fermentation. Different protective agents were investigated to increase the survival of E. faecium A028 during hot air drying. Maltodextrin (MTD) provided the highest survival rate at 83.9% during 24 h of drying. RB-SSF effectively enhanced the production rate of probiotic strain cultivation in SBM, while MTD acted as a cell-protective agent and maintained the survival of E. faecium A028 during thermal drying.

Synergistic combination of cryoprotectants for high freeze-dried survival rate and viable cell counts of Streptococcus thermophilus

Vacuum freeze-drying is one of the common methods to prepare probiotic powder. However, the low temperature and low moisture content could lead to the death of probiotics. The method of adding cryoprotectants is efficient to improve the survival rate of probiotics during vacuum freeze-drying. The synergistic combination of different cryoprotectants could play a better protective effect. However, the principle of the synergistic combination of different cryoprotectants during vacuum freeze-drying is not clear. In this study, literature review and analysis were firstly used to reveal commonly used cryoprotectants for coccus. Taking the price of cryoprotectants into account, the combination is preliminarily determined as sucrose/skim milk/sodium glutamate. Then, taking Streptococcus thermophilus 937 as the research target strain, the effect of this cryoprotectant combination was verified by a single-factor screening experiment and concentration optimization of cryoprotectants. It was found that the preferred cryoprotectant combination for Streptococcus thermophilus 937 is 6% sucrose/8% skim milk/4% sodium glutamate, with the freeze-dried survival rate and viable counts being 90.59% and 1.78 × 1011CFU/g, respectively. Meanwhile, this cryoprotectant combination also had a good protective effect on the other two cocci, Streptococcus thermophilus Grx02 and Enterococcus faecium 218. This result might have guiding and reference significance on the vacuum freeze-drying of coccus.

Evaluating the Stability of a Novel Nutraceutical Formulation Combining Probiotic Limosilactobacillus fermentum 296, Quercetin, and Resveratrol Under Different Storage Conditions.

This study evaluated the stability of a novel nutraceutical formulation composed of the probiotic Limosilactobacillus fermentum 296, quercetin (QUE), and resveratrol (RES) (LFQR) under different storage conditions. The effects of different relative humidities (RH; 11, 22, and 33%) and storage temperatures (refrigeration temperature -4°C and room temperature -25°C) on the stability of LFQR were evaluated through the determination of thermal stability, viable cell counts, bacterial physiological status, antioxidant capacity, and contents of QUE and RES during long-term storage. RH did not affect endothermic reactions and mass reduction in LFQR. After a 15-day-humidification period, L. fermentum 296 had higher viable cell counts in LFQR under refrigeration temperature storage when compared to room temperature storage regardless of the RH. The physiological status of L. fermentum 296 in LFQR was overall similar during 90days of storage (11% RH) under refrigeration and room temperature. L. fermentum 296 had the highest viable cell counts (> 6 log CFU/g) in LFQR up to day 90 of refrigeration storage (11% RH). LFQR kept high contents of QUE and RES and maintained antioxidant capacity during 90days of storage under refrigeration and room temperature. The results showed that the higher stability and functionality of LFQR during long-term storage should be guaranteed under 11% RH and refrigeration temperature.

Extractive Fermentation as A Novel Strategy for High Cell Mass Production of Hetero-Fermentative Probiotic Strain Limosilactobacillus reuteri

This study reports on a novel technique to enhance the high cell mass and viable cell counts of the heterofermentative probiotic strain, Limosilactobacillus reuteri. This is the first report on the cultivation of L. reuteri, which was incorporated with weak base anion-exchange resins to remove the accumulating lactic acid in the fermentation broth. Two anion-exchange resins—Amberlite IRA 67 and IRA 96—were found to have a high adsorption capacity with lactic acid. Batch fermentation and fed-batch cultivation were further analyzed using IRA 67 resins, as this application resulted in a higher maximum number of viable cells. The in situ application of anion-exchange resins was found to create shear stress, and thus, it does not promote growth of L. reuteri; therefore, an external and integrated resin column system was proposed. The viable cell count from batch fermentation, when incorporated with the integrated resin column, was improved by 71 times (3.89 × 1011 ± 0.07 CFU mL−1) compared with control batch fermentation (5.35 × 109 ± 0.32 CFU mL−1), without the addition of resins. The growth improvement was achieved due to the high adsorption rate of lactic acid, which was recorded by the integrated IRA 67 resin system, and coupled with the stirred tank bioreactor batch fermentation process.

Co‐extrusion and extrusion microencapsulation: Effect on microencapsulation efficiency, survivability through gastrointestinal digestion and storage

AbstractProbiotic is a functional food ingredient that is commonly used in the manufacturing of fermented dairy products and vegetable‐based foods. The consumption of probiotics has been claimed to confer health benefits to the host. However, probiotic cells are sensitive to harsh environments such as extreme pH and enzymes in the gastrointestinal tract. Hence, the microencapsulation technique is often adopted to shield probiotics from the outer environment. This review introduces a more advanced extrusion technique called co‐extrusion, which has been used to microencapsulate probiotics over the last few years. Both co‐extrusion technique and extrusion technique in microencapsulating probiotics were discussed extensively in this article. Furthermore, the impact of encapsulating probiotics in contrast with unencapsulated cells was also presented. This review highlighted some of the factors that might cause low viable cell count during microencapsulation and large microbead size. Lastly, the survivability of encapsulated probiotics in gastrointestinal digestion and storage under different temperatures were evaluated and the importance of probiotic microencapsulation was also emphasized.Practical ApplicationsThe detailed information on extrusion and co‐extrusion techniques for probiotics microencapsulation is presented in this review. This information is useful for researchers and industrialists in understanding and applying both encapsulation techniques on probiotics for different purposes. Through this paper, the readers would also gain more insight into the factors affecting the viability and microbead size of the encapsulated probiotic to further optimize the extrusion and co‐extrusion encapsulation process. Furthermore, the ideal storage temperature and additional drying process for the encapsulated probiotic identified in this review would open opportunities for industrialists to produce functional probiotic products with a high viable cell count.

Influence of probiotics on physico-chemical and organoleptic characteristics of sweet orange juice

Aim: The study was undertaken to evaluate the survival probiotic organisms and its influence on the physical, chemical, nutritional and sensory characteristics of sweet orange juice. Methodology: Two samples of probiotic juice were prepared with 10 percent innoculum containing LAB strains (Lactobacillus bulgaricus and Lactobacillus plantarum). Sample A (without encapsulated strains) and Sample-B (with encapsulated strains) were prepared and incubated for 10hrs at 35oC. After incubation, the physico-chemical analysis of both the samples were analyzed for TSS, pH, acidity, total sugars, reducing sugars and ascorbic acid content. Results: The results of TSS, pH, acidity, total sugars, reducing sugars and ascorbic acid content for sample –A and Sample –B were 11.4˚Brix, 3.51, 0.82 percent, 6.1 percent, 1.5 percent, 4.6 percent, 40mgml-1 and 11.6˚ Brix, 3.68, 0.77 percent, 6.4 percent, 1.7 percent, 4.9 percent, 40 mg ml-1, respectively. Sensory evaluation revealed that overall acceptance of probiotic juice containing encapsulated strains and free strains in the first week was 8.3 and 7.8, respectively. Even after 4 weeks of storage, the overall acceptance for juice with encapsulated strains was better than free strains with a score of 7.5 and 7.0 at the end of storage period. Interpretation: The sweet orange juice with encapsulated strains has high viable cell count (109cfu ml-1) even after 4 weeks of storage resulted in stable therapeutic probiotic sweet orange juice. It is further, suitable for commercial production of probiotic sweet orange juice with probiotic cultures.

Selection of indigenous Lacticaseibacillus paracasei CD 4 for production of gluten-free traditional fermented product Bhaturu

ABSTRACT Celiac disease is an autoimmune disorder triggered by immune-toxic peptides generated through incomplete hydrolysis of wheat gluten. This study reports the screening of potential probiotic strains to hydrolyze wheat gluten. The selected strain was used in the production of gluten-free traditional fermented and fried bread, Bhaturu. Lacticaseibacillus paracasei CD4 and Limosilactobacillus gastricus BTM7 produced halo zones on gluten containing agar plates. Lc. paracasei CD4 resulted in 2.3 folds higher free amino acid content in gluten-based medium. The SDS-PAGE analysis indicated that gluten was degraded into high and low molecular weight peptides. The fermentation of wheat flour was conducted with 7.0 log CFU/g of Lc. paracasei CD4 for 24 h. A fermentation time of 12 h was selected based on higher viable cell count, ammoniacal-nitrogen, and titratable acidity. The fermentation resulted in decrease in albumin, glutenin and gliadin contents (P > .05). The Bhaturu prepared from fermented dough had higher acceptability based on sensory evaluation.

Encapsulation and dispersion of Lactobacillus acidophilus in a chocolate coating as a strategy for maintaining cell viability in cereal bars

Flour from Pereskia aculeata leaf and green banana were used as ingredients in the formulation of a cereal bar with added Lactobacillus acidophilus LA02-ID-1688. Encapsulation in a calcium-alginate hydrogel reinforced with magnesium hydroxide was used as a strategy to protect the probiotic cells under gastrointestinal conditions and to prolong shelf-life. The results are relevant especially for maintaining cell viability during shelf-life; a challenge for the food industry in relation to dry probiotic products. Encapsulation promoted the protection of probiotic cells in simulated gastric and intestinal conditions, allowing the maintenance of high viable cell counts (> 10 log CFU, colony forming unit). Encapsulation also contributed to cellular protection under extreme temperature conditions, with reductions of cell viability of < 1 logarithmic cycle when the capsules were subjected to 55ºC/10 min. Even at 75ºC/10 min, encapsulation protected the probiotic cells 3-times greater than the free-cells. The food bar proved to be rich in dietary fiber (19 g 100 g−1), lipids (12.63 g 100 g−1) and showed an appreciable protein content (5.44 g 100 g−1). A high viable probiotic cell count on storage over 120 days (12.54 log CFU) was observed, maintaining a probiotic survival rate > 90% and viability levels sufficient to promote health benefits.

Fermented soy whey induced changes on intestinal microbiota and metabolic influence in mice

Soy whey (SW) is generated as process waste while preparing soy protein isolates (SPI), and causing severe environmental pollution. Therefore, its value-added utilization is of prime importance for transforming and upgrading traditional industry. This study aims to utilize SW as a substrate for the growth of probiotics and produce a SW based synbiotics. By a series of trials, the effect of the dietary supplementation with this fermented SW (FSW) was analyzed on ICR mice's body weight, metabolites, and intestinal microbiota in 4 weeks. The results showed that, when SW was concentrated 15 times, the count of viable Lactobacillus casei reached 3.4×109 CFU/mL by liquid fermentation method, which was the highest viable cell count among all test strains. In this FSW, the protein, amino acid, total dietary fibre, soluble dietary fibre, and oligosaccharide were 2.10%, 1.63%, 0.52%, 0.51% and 0.79%, respectively. Compared to two control group, the total yields of the short chain fatty acids (SCFAs) were significantly improved (75%–125% at average), while the SCFAs structure was also significantly changed (especially acetic acid and butyrate) in the faeces of mice fed FSW. Meanwhile, FSW dietary addition was associated with the diversity and richness of the intestinal microbiota. Obviously, with mice's body weight loss, Firmicutes/Bacteroides ratio reduced accordingly (< 1.21), and the abundance of Akkermansia muciniphila was significantly increased (the maximum amount was about 0.013%). In summary, our results indicated that the dietary supplementation of FSW affected mice's intestinal microbiota and metabolism and improved their health profile.

Effects of fat content on the textural and in vivo buccal breakdown properties of soy yogurt.

This study aimed to evaluate the effects of fat content on the textural and in vivo buccal breakdown properties of soy yogurt (SY) at different pH (5.4, 5.0, and 4.6). The microbial analysis, textural and rheological properties, and interfacial protein composition of all the samples were monitored. Microbial results suggested that the increased fat content in SY-5.0 and SY-4.6 resulted in significantly high viable cell counts of lactic acid bacteria (LAB). Textural studies demonstrated that the presence of a low fat content (1-3%) significantly reduced the hardness, springiness, and gumminess of the sample, but this effect was negligible with the addition of fat content (4-5%). The apparent viscosity and thixotropy of the SY-4.6 sample increased as the fat content increased. in vivo buccal digestion showed that a high fat content (2-4%) reduced the number of chews and chewing durations, which might be correlated with high oil droplet release (%) after mastication.

Evaluation and Application of Different Cholesterol-Lowering Lactic Acid Bacteria as Potential Meat Starters

A total of 115 isolates of lactic acid bacteria were screened from traditional fermented foods in Guizhou Province, People's Republic of China. The cholesterol removal rates of 86 isolates ranged from 7.29 to 25.66%, and 18 isolates showed a cholesterol removal rate of more than 15%. According to the results of physiological and biological tests, 13 isolates were selected to determine the fermentation performance; 9 isolates-MT-4, MT-2, PJ-15, SR2-2, SQ-4, SQ-7, ST2-2, ST2-6, and NR1-7-had high tolerance of bile salt and acid and had a survival rate of more than 96% under pH 3.0 and 0.3% bile salt. ST2-2, SR2-2, NR1-7, SQ-4, and MT-4 had high survival rate in different concentrations of NaCl and NaNO2 under different temperatures. According to BLAST comparison results of the 16S rRNA sequence in the GenBank database and the genetic distance of the 16S rRNA sequence with an ortho-connected algorithm, SR2-2, NR1-7, and ST2-2 were identified as Lactobacillus plantarum, MT-4 was identified as Lactobacillus pentosus, and SQ-4 was identified as Lactobacillus paraplantarum. Moreover, strains SQ-4 and MT-4 were added to fermented beef. Results showed that the fermented beef had delicious taste and was popular to consumers because of its proper pH, pleasant colors, high viable cell count, and suitable content of bound and immobilized water. These results provide a basis for the development of new starter formulation for the production of high-quality fermented meat products.

The nutrient requirements of Lactobacillus acidophilus LA-5 and their application to fermented milk

Lactobacillus acidophilus LA-5 is a suitable probiotic for food application, but because of its slow growth in milk, an increase in its efficiency is desired. To shorten the time required for fermentation, the nutrient requirements of L. acidophilus LA-5 were analyzed, including the patterns of consumption of amino acids, purines, pyrimidines, vitamins, and metal ions. The nutrients required by L. acidophilus LA-5 were Asn, Asp, Cys, Leu, Met, riboflavin, guanine, uracil, and Mn2+, and when they were added to milk, the fermentation time of fermented milk prepared by L. acidophilus LA-5 alone was shortened by 9 h, with high viable cell counts that were maintained during storage of nutrient-supplemented fermented milk compared with the control. For fermented milk prepared by fermentation with Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, and L. acidophilus LA-5, viable cell counts of L. acidophilus LA-5 increased 1.3-fold and were maintained during storage of nutrient-supplemented fermented milk compared with the control. Adding nutrients had no negative effect on the quality of the fermented milk. The results indicated that suitable nutrients enhanced the growth of L. acidophilus LA-5 and increased its viable cell counts in fermented milk prepared by L. acidophilus LA-5 alone and mixed starter culture, respectively.

Effect of different fermentation strategies on Bacillus thuringiensis cultivation and its toxicity towards the bagworm, Metisa plana Walker (Lepidoptera: Psychidae)

The effect of batch and fed-batch fermentation on the cultivation performance of Bacillus thuringiensis was investigated using a 5-l stirred tank bioreactor. Significantly higher viable cell count (> 1.5 × 1012 CFU/ml) was obtained in the fed-batch compared to batch fermentation (1.4 × 1012 CFU/ml). Glucose feeding during the fermentation seemed to enhance cell growth but failed to enhance the sporulation rate. It was found that sporulation and δ-endotoxin synthesis in fed-batch fermentation could be enhanced by the application of optimal dissolved oxygen tension (DOT) control strategy without affecting the cell growth. Fed-batch cultivation with feeding at the exponential growth phase where the DOT was switched from 80 to 40% at 12 h of cultivation recorded the highest spore count of 7.1 × 1011 spore/ml. Cultures obtained from batch cultivation, as well as fed-batch cultivation with feeding at lag or exponential growth phase and the application of optimal DOT control strategy, recorded the presence of δ-endotoxin; however, none was detected in intermittent fed-batch fermentation. Bioassay data against the bagworm Metisa plana Walker (Lepidoptera: Psychidae) recorded the highest corrected mortality (80%) at 7 days of treatment (DAT), using the culture obtained from fed-batch cultivation with feeding during the exponential growth phase, and the DOT was switched from 80 to 40% at 12 h of cultivation. It is important to note that all cultures containing δ-endotoxin exhibited 100% mortality towards M. plana at 14 DAT.

Effect of Liquid and Charcoal Based Consortium Biofertilizers Amended with Additives on Growth and Yield in Chickpea (Cicer arietinum L.)

The present study was carried out to compare the shelf life and bio-efficacy of liquid and charcoal based biofertilizers of LGR33+RB1 amended with different additives viz.0.1% CMC, 2% PVP and 10mM trehalose stored at 4oC and 28oC upto 300 days in chickpea. Significantly high viable cell count of bacterial population as well as plant growth promoting (PGP) traits viz. IAA production and P solubilization at an interval of 30 days were recorded in liquid based biofertilizer treatments with additives during the entire study period (300 days) at 4oC and 28oC as compared to charcoal based biofertilizer treatments. However, among different additives amendment with 0.1% CMC showed maximum viable population and PGP traits in both liquid as well as charcoal based biofertilizers. In vivo studies, all liquid as well as charcoal based biofertilizer treatments with additives improved growth parameters in chickpea as compared to recommended consortium treatment without additives. Liquid biofertilizer treatment LGR33+RB1+0.1% CMC recorded maximum plant height, chlorophyll content, number of nodules, dry weight of nodules as well as leghaemoglobin content, soil enzyme activity, total N and P content of shoot and soil along with improvement in grain yield over uninoculated control.