Identification of Aflatoxigenic Fungi and Detection of Their Aflatoxin in Red Chilli (<i>Capsicum annuum</i>) Samples Using Direct Cultural Method and HPLC

Aflatoxins are the potential lethal toxin produced by Aspergillus sp. important health hazard throughout the world. In this study, 26 Aspergillus sp. have been isolated from 50 samples of red chilli collected throughout the country. These 26 isolates were grown primarily on agar media to identify the aflatoxin producing species. It is possible to distinguish A. flavus strains from other Aspergillus sp. developing orange colour on the reverse of the plates. The Coconut Cream Agar (CCA) is used to detect aflatoxin producer strains having blue fluorescence when exposed to a UV-light. Several other media were used for morphological characteristics of Aspergillus sp. Out of 26 isolates, four isolates were confirmed as Aspergillus sp. These isolates were subjected to cross contamination with freshly ground, sterile maize and after 15 days of incubation the contaminated maize were analyzed by HPLC and found aflatoxin in each of the sample containing 186 ppb (max.). This study was conducted to assay the ability to produce aflatoxins by the Aspergillus spp. isolated from red chilli (Capsicum annuum L. Solanaceae) available throughout the country. The results found in the experiment are much more behind the acceptable limit according to some international standard. As red chilli is a widely used spice in Bangladesh, the proper controlling measures may be taken for controlling the surveillance of aflatoxinic fungi like as use of bio-pesticides, proper drying method and storage conditions.

Effects of Biochar on the Abundance of Three Agriculturally Important Soil Bacteria

An in vitro study was conducted to make a comparative study of biochar and biomass on soil bacteria. The responses of three agriculturally important bacteria viz., Bradyrhizobium, Sulphate reducing and Iron oxidizing bacteria, were studied. Total viable counts were also made. Three different types of biomasses viz., rice husk, rice straw and saw dust, and biochars produced thereof were used for the study. The biomasses or biochars were applied to the soil at a rate of 5 t/ha. The study included seven different treatments of biomasses and corresponding biochars including a control. Total counts were made on the original materials as well as on the treated soils at 30, 60 and 90 days of incubation. Bacterial count was higher in all the biomass treated soils than the corresponding biochar treated ones including control. Although the presence of Bradyrhizobium, sulphate reducing and iron oxidizing bacteria were not noted in the fresh soils, their presence, however, was noted after incubation periods. The counts of all three bacteria are however lower in the biochar treated soils than the corresponding biomass treated soils. The paper discusses about the microbial soil health vis-à-vis biochar application, indicating that the materials exert negative effect on the soil microbial population and thereby likely to jeopardize soil health and crop production.

Edible Growth Medium: A New Window for Probiotic Research

Conventional growth media for microbes contains lots of non-edible components that are harmful to consume when the organism is ready to intake—like probiotics growing in chemical media (Lactobacillus grown in MRS media). The study was conducted to develop an edible and low-cost growth media that supports the growth of probiotics Lactic Acid bacteria for the enhancement of probiotic research. The 04 isolates of Lactobacillus (L. plantarum, L. rhamnosus, L. ferciminis and L. bifarmentans) and 02 Bifidobacterium (B. infantis and B. Bifidum) were used for the evaluation of medium efficacy. To formulate the edible culture media, 04 vegetables and 02 pulses were used. The media was formulated in different formulations. For Lactobacillus, maximum growth was observed at MM-2 media formulation that was about 15.62 log CFU/ml for L. plantarum and compared to MRS media that was 11.78 log CFU/ml. Bifidobaterium showed the highest viability at MW-1 edible media formulation which was about 12.72 log CFU/ml whereas in Bifidobacteria selective media the cell viability was 12.48 log CFU/ml. The edible media has no toxic or unhealthy effect on mice while trailing in an animal model and shows excellent results in encapsulation with alginate. In comparison with the performance of traditional chemical media, the formulated media were found to be cost-effective and safe for human consumption.