Edible bird nests (EBNs) are highly demanded globally. The industry was recently affected by an import ban to China due to high nitrite levels.Subsequently, many concerns have been raised. In this study, the microbial composition of both raw and commercial EBNs was investigated. The raw EBNs were purchased from swiftlet farms: Kuala Sanglang (Perlis), Pantai Remis (Perak), Kluang (Johor), Kajang (Selangor) and Kota Bharu (Kelantan). The commercial nests were purchased from five different Chinese traditional medicinal shops (Companies A-E) in Malaysia and one from Indonesia (Medan). A total of 123 and 34 isolates were successfully identified from unboiled raw and commercial EBNs respectively. The highest average CFU (1.77 x 104) was associated with raw EBNs obtained from Kluang, while for the commercial EBNs, those obtained from Company M1 had the highest CFU (5.50 x 104). Bacillus sp. accounted for the highest isolated species from both unboiled raw and commercial EBNs. Bacillus sp. and Brevibacillus sp. were mainly isolated from the boiled EBNs. Bacillus spp. were the dominant bacterial groups in all the raw EBNs except for those obtained from Kajang. The average number of bacteria isolated from the raw EBNs (average = 7) was higher compared with those isolated from the commercial EBNs (average = 4). The highest average number of bacterial isolates was reported in the raw EBNs obtained from Kota Bharu. Among the commercial EBNs, one EBN sample each from Companies A and M1 showed the highest number of isolates (n = 10). In general, there was a significant reduction in the number of bacteria isolated after boiling the EBNs. Raw EBNs obtained from Kajang had a distinct pool of bacterial species where the majority of the isolated species belonged to Staphylococcus species. The associated health impacts of these microorganisms to the consumers and public need to be addressed.
Multidrug resistance to pathogens has posed a severe threat to public health. The threat could be addressed by antimicrobial peptides (AMPs) with broad-spectrum suppression. In this study, Brevibacillus halotolerans 7WMA2, isolated from marine sediment, produced AMPs against Gram-positive and Gram-negative bacteria. The AMPs were precipitated by ammonium sulfate 30% (w/v) from culture broth and dialyzed by a 1 kDa membrane. Tryptone Soy Agar (TSA) was used for the cultivation and resulted in the largest bacteria-inhibiting zones under aerobic conditions at 25 °C, 48 h. An SDS-PAGE gel overlay test revealed that strain 7WMA2 could produce AMPs of 5-10 kDa and showed no degradation when held at 121 °C for 30 min at a wide pH 2-12 range. The AMPs did not cause toxicity to HeLa cells with concentrations up to 500 µg/mL while increasing the arbitrary unit up to eight times. The study showed that the AMPs produced were unique, with broad-spectrum antimicrobial ability.
Black pepper production in Malaysia was restricted by various diseases. Hazardous chemical products appear to be the best solution to control diseases in black pepper cultivation. However, persistence of chemical residues in peppercorns could affect the quality of exports and consumptions. Application of fertilizers is crucial to sustain pepper growth and high yield. But, continuous use of chemical fertilizers could affect the soil ecosystem and eventually restrict nutrient uptake by pepper roots. Therefore, we propose biological approaches as an alternative solution instead of chemical products to sustain pepper cultivation in Malaysia. In this study, we have isolated a total of seven indigenous rhizobacteria antagonistic to soil-borne Fusarium solani, the causal fungus of slow decline, the most serious debilitating disease of black pepper in Malaysia. The isolated bacteria were identified as Bacillus subtilis, Bacillus siamensis, Brevibacillus gelatini, Pseudomonas geniculata, Pseudomonas beteli, Burkholderia ubonensis and Burkholderia territorii. These bacteria were effective in production of antifungal siderophore with the amount of 53.4 %-73.5 % per 0.5 mL of cell-free supernatants. The bacteria also produced appreciable amount of chitinase with chitinolytic index was ranged from 1.19 to 1.76. The bacteria have shown phosphate solubilizing index within 1.61 to 2.01. They were also efficient in ACC deaminase (0.52 mM-0.62 mM) and ammonia (60.3 mM-75.3 mM) production. The isolated antagonists were efficacious in stimulation of black pepper plant growth and root development through IAA (10.5 μg/mL-42.6 μg/mL) secretion. In conclusion, the isolated rhizobacteria are potent to be developed not only as biocontrol agents to minimize the utilization of hazardous chemicals in black pepper disease management, but also developed as bio-fertilizers to improve black pepper plant growth due to their capabilities in plant growth-promotion.