The present study aimed to identify potential endophytic bacteria antagonistic against three soil-borne fungal pathogens, Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum f.sp. ciceri causing root rot, collar rot, and fungal wilt diseases in chickpea plants, respectively. A total of 255 bacterial endophytes were isolated from the leaves, stems, and roots of seven different crop plants (chickpea, tomato, wheat, berseem, mustard, potato, and green pea). The dual culture-based screening for antifungal properties indicated that three endophytic isolates had strong inhibition (>50%) against all three pathogens tested. Based on morphological, biochemical, and molecular characterization, the selected isolates (TRO4, CLO5, and PLO3) were identified as different strains of Bacillus subtilis. The bacterial endophytes (TRO4 and CLO5) were positive for plant growth promoting (PGP) traits viz., ammonia, siderophore, and indole-3-acetic acid (IAA) production. The bio-efficacy of the endophytes (TRO4, CLO5, and PLO3) was tested by an in planta trial in chickpea pre-challenged with R. solani, S. rolfsii, and F. oxysporum f.sp. ciceri. The B. subtilis strains TRO4 and CLO5 were found to be effective in reducing percent disease incidence (p ≤ 0.05) and enhancing plant growth parameters. The different root parameters viz. root length (mm), surface area (cm²), root diameter (mm), and root volume (cm³) were significantly (p ≤ 0.05) increased in TRO4 and CLO5 inoculated chickpea plants. Confocal Scanning Laser Microscopy showed heavy colonization of bacteria in the roots of endophyte-inoculated chickpea plants. The inoculation of endophytic Bacillus subtilis strains TRO4 and CLO5 in chickpea plants through seed biopriming reduced the accumulation of superoxide, enhanced the plant defense enzymes, and induced the expression of Pathogenesis-Related (PR) genes. Semi-quantitative analysis of defense-related genes showed differential activation of PR genes (60srp and IFR) by endophyte inoculation. The results of the present study reveal the antagonistic potential of B. subtilis strains TRO4 and CLO5 against three major soil-borne fungal pathogens and their ability to suppress wilt complex disease in chickpea plants. This is the first report on the simultaneous suppression of three major soil-borne fungal pathogens causing wilt complex in chickpea plants by endophytic B. subtilis strains.

Cottonseed is one of the important by-products of the cotton crop. Researchers claim that cottonseed with less than 0.45% of gossypol is quite good for human consumption and animal feeding because it is a rich source of protein, edible oil, and energy. Total and free gossypols are the influencing parameters that reduce the edible nature of the cottonseed. In the present work, multiple quadratic regression models have been prepared to predict the reduction in the free and total gossypol percent. This response surface method (RSM)-based approach was applied to investigate the combined effect between input parameters such as acetone level, time of extraction, liquid-to-solid ratio (LSR), and the number of extraction cycles, whereas output responses are free and total gossypol reduction percentage. Analysis of Variance (ANOVA) has been performed to determine the highly significant parameter. The optimum combination of input parameters was determined using the RSM-based desirability approach, and confirmatory experiments were performed to validate the combination. Results revealed that the number of extraction cycles and liquid-to-solid ratio significantly affects the reduction of free and total gossypol levels. The values of r-square were found above 0.9, which indicates that the developed models are suitable and reliable for predicting free and total gossypol reduction percentage.

Gossypol, a toxic polyphenolic compound, limits the use of cottonseed cake (CSC) in animal feed. Different approaches have been employed to detoxify gossypol and improve the nutritive properties of feed. Microbial fermentation improves the nutritive quality of CSC by increasing lysine content and reducing free and bound gossypol. In this study, microbial fermentation was scaled up under batch conditions using a prototype device at the capacity of 40 kg per day. The mixed fungal culture C. tropicalis + S. cerevisiae was used for fermentation. An industrial trial was taken to ascertain the gossypol detoxification efficiency. The fermented CSC obtained under scale-up process had 60 to 80% and 40 to 60% reduction of free and bound gossypol, respectively, compared with raw CSC. The fermented CSC demonstrated an increase in crude protein (4 to 12%) and lysine (0.3 to 0.4%) and decrease in crude fibre (3 to 11%). The fermented CSC met the standards of US Food and Drug Administration in terms of its nutritional property. Thus, the simple method described in this study could be adopted for the production of detoxified CSC for use in the animal feed industry.

Cottonseed is the major by-product of cotton and it contains about 33% protein which shows its potential to be utilized for food applications. However, the presence of gossypol restricts its use for edible purpose. The previous attempts made for gossypol reduction in cottonseed meal resulted in poor extraction efficiency and loss in protein quality. The present study aimed at efficient removal of gossypol from the cottonseed kernel powder to produce the high-protein flour with an excellent amino acid profile. The process was divided into two stages; in the first part, gossypol was extracted from the kernel powder at optimized conditions (acetone-to-water ratio 90:10, sample-to-solution ratio (1:10), 30-min shaken time, and number of extractions 4). Further, the oil was removed from the acetone-treated sample that yielded 15.7% oil. In the second-stage processing, the de-oiled sample was treated at optimized conditions (ethanol-to-water ratio 50:50, citric acid 0.2 M, sample-to-solvent ratio 1:15, and incubation time 30 min) in a water bath at 100 ℃ temperature. The cottonseed flour produced in the present study had 64% protein, 23% carbohydrates, 0.24% total gossypol, and all essential amino acids except tryptophan.