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.

Distribution of Cr,Cd,Cu,Pb and Zn in organs of three selected local fish species of Turag river,Bangladesh and impact assessment on human health

The current study estimates the contamination status of heavy metals in fish organs of three local fish species including Amblypharyngodon microlepis(Mola),Trichogaster chuna(Chuna Khalisha)and Annaldale Loach(Gutum fish)which were collected from Turag river during the months from January to March 2022.The heavy metal concentrations of river water and fish organs were assessed through Atomic Absorption Spectrophotometer(AAS).Heavy metals in river water was detected in the order of Ni>Zn>Cu>Cd>Pb>Cr while metal accumulation in the fish organs were detected in the order of Zn>Cr>Cu>Pb>Cd,Zn>Cu>Cr>Pb>Cd and Zn>Cu>Cr>Pb>Cd for Trichogaster chuna,Amblypharyngodon microlepis and Annaldale Loach respectively.Among the detected heavy metals,highest contamination factor(CF)of Zn(1.104198)in intestine and lowest CF of Cu(0.00315)was detected in muscle of Amblypharyngodon microlepis(Mola).On the other hand,highest CF of Cd(1.072772)in liver and lowest CF of Zn(0.0225016)in gill of Trichogaster chuna(Chuna Khalisha)was detected.In case of Annaldale Loach(Gutum fish),highest CF of Cu(0.304122)in liver and lowest CF of Zn(0.002593)in intestine was detected.The total target hazard quotients(TTHQ)values of Amblypharyngodon microlepis in liver(1.18816)exceeded allowable threshold of 1 while TTHQ values in the muscle(1.8862)and liver(1.03995)of Annaldale Loach(Gutum fish)surpassed the acceptable standard limit as well.The TTHQ values(Gill-0.18764,Muscle-2.1633,Intestine-1.68741,liver-1.03995,kidney-1.82188)for all of the organs of Trichogaster chuna(Chuna Khalisha)exceeded the acceptable standard limit which indicated possible non-cancer risk for all consumers and some of the fishes found unsafe if they are consumed for a longer time.However,the target cancer risk(TCR)values indicated no potential cancer risks by consumption of those fishes.The regulatory authorities should pay more attention to reduce the river water contamination through industrial effluents which might affect public health.